added CRC32, CRC32C, SHA1, SHA256 and CRC64NVME (#195)

Cargo.toml

@@ -24,7 +24,7 @@ http2 = ["reqwest/http2"]
 localhost = []
 
 [workspace.dependencies]
-uuid = "1.18"
+uuid = "1.19"
 futures-util = "0.3"
 futures-io = "0.3"
 reqwest = { version = "0.12", default-features = false }
@@ -49,7 +49,7 @@ async-stream = "0.3"
 async-trait = "0.1"
 base64 = "0.22"
 chrono = { workspace = true, features = ["serde"] }
-crc = "3.4"
+crc-fast = "1.8"
 dashmap = "6.1.0"
 env_logger = "0.11"
 hmac = { version = "0.12", optional = true }
@@ -64,6 +64,7 @@ regex = "1.12"
 ring = { version = "0.17", optional = true, default-features = false, features = ["alloc"] }
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
+sha1 = "0.10"
 sha2 = { version = "0.10", optional = true }
 urlencoding = "2.1"
 xmltree = "0.12"
@@ -104,3 +105,8 @@ name = "load_balancing_with_hooks"
 name = "s3-api"
 path = "benches/s3/api_benchmarks.rs"
 harness = false
+
+[[bench]]
+name = "bench_checksums"
+path = "benches/s3/bench_checksums.rs"
+harness = false

benches/s3/bench_checksums.rs

@@ -0,0 +1,53 @@
+// MinIO Rust Library for Amazon S3 Compatible Cloud Storage
+// Copyright 2025 MinIO, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use criterion::{Criterion, Throughput, criterion_group, criterion_main};
+use minio::s3::utils::{
+    crc32_checksum, crc32c, crc64nvme_checksum, md5sum_hash, sha1_hash, sha256_checksum,
+};
+
+fn bench_checksums(c: &mut Criterion) {
+    let sizes = vec![
+        ("1KB", 1024),
+        ("10KB", 10 * 1024),
+        ("100KB", 100 * 1024),
+        ("1MB", 1024 * 1024),
+        ("10MB", 10 * 1024 * 1024),
+    ];
+
+    for (name, size) in sizes {
+        let data = vec![0u8; size];
+
+        let mut group = c.benchmark_group(format!("checksum_{}", name));
+        group.throughput(Throughput::Bytes(size as u64));
+
+        group.bench_function("CRC32", |b| b.iter(|| crc32_checksum(&data)));
+
+        group.bench_function("CRC32C", |b| b.iter(|| crc32c(&data)));
+
+        group.bench_function("CRC64NVME", |b| b.iter(|| crc64nvme_checksum(&data)));
+
+        group.bench_function("MD5", |b| b.iter(|| md5sum_hash(&data)));
+
+        group.bench_function("SHA1", |b| b.iter(|| sha1_hash(&data)));
+
+        group.bench_function("SHA256", |b| b.iter(|| sha256_checksum(&data)));
+
+        group.finish();
+    }
+}
+
+criterion_group!(benches, bench_checksums);
+criterion_main!(benches);

macros/src/lib.rs

@@ -74,6 +74,14 @@ extern crate proc_macro;
 ///    // this test will not run if the MinIO server is NOT running in Express mode
 /// }
 /// ```
+/// - `ignore`: Mark the test as ignored (skipped by default). Run with `cargo test -- --ignored` to include.
+/// ```no_run
+/// use minio_common::test_context::TestContext;
+/// #[minio_macros::test(ignore = "Requires newer server version")]
+/// async fn my_test(ctx: TestContext, bucket_name: String) {
+///    // this test is skipped by default
+/// }
+/// ```
 #[proc_macro_attribute]
 pub fn test(
     args: proc_macro::TokenStream,

macros/src/test_attr.rs

@@ -32,6 +32,8 @@ pub(crate) struct MacroArgs {
     no_bucket: darling::util::Flag,
     object_lock: darling::util::Flag,
     no_cleanup: darling::util::Flag,
+    /// Mark test as ignored (skipped by default, run with `cargo test -- --ignored`)
+    ignore: Option<String>,
 }
 
 impl MacroArgs {
@@ -171,28 +173,33 @@ fn generate_tokio_test_header(args: &MacroArgs, sig: TokenStream) -> TokenStream
         .as_ref()
         .map(ToString::to_string)
         .or(std::env::var("MINIO_TEST_TOKIO_RUNTIME_FLAVOR").ok());
-    match (flavor, args.worker_threads) {
+
+    // Generate #[ignore = "reason"] if specified
+    let ignore_attr = args
+        .ignore
+        .as_ref()
+        .map(|reason| quote!(#[ignore = #reason]));
+
+    let tokio_attr = match (flavor, args.worker_threads) {
         (Some(flavor), None) => {
-            quote!(#[::tokio::test(flavor = #flavor)]
+            quote!(#[::tokio::test(flavor = #flavor)])
-            #sig
-                )
         }
         (None, Some(worker_threads)) => {
-            quote!(#[::tokio::test(worker_threads = #worker_threads)]
+            quote!(#[::tokio::test(worker_threads = #worker_threads)])
-            #sig
-                )
         }
         (None, None) => {
-            quote!(#[::tokio::test]
+            quote!(#[::tokio::test])
-            #sig
-                )
         }
         (Some(flavor), Some(worker_threads)) => {
-            quote!(#[::tokio::test(flavor = #flavor, worker_threads = #worker_threads)]
+            quote!(#[::tokio::test(flavor = #flavor, worker_threads = #worker_threads)])
+        }
+    };
+
+    quote!(
+        #ignore_attr
+        #tokio_attr
         #sig
     )
-        }
-    }
 }
 
 fn generate_express_skip_logic(args: &MacroArgs, span: proc_macro2::Span) -> TokenStream {

src/s3/aws_chunked.rs

@@ -0,0 +1,999 @@
+// MinIO Rust Library for Amazon S3 Compatible Cloud Storage
+// Copyright 2025 MinIO, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! AWS Chunked encoding with trailing checksum support.
+//!
+//! This module implements the `aws-chunked` content encoding format used by S3
+//! for streaming uploads with trailing checksums. The format allows computing
+//! checksums incrementally while streaming data, with the checksum value sent
+//! as a trailer at the end of the body.
+//!
+//! # Unsigned Protocol Format (STREAMING-UNSIGNED-PAYLOAD-TRAILER)
+//!
+//! ```text
+//! <hex-chunk-size>\r\n
+//! <chunk-data>\r\n
+//! ...
+//! 0\r\n
+//! x-amz-checksum-<algorithm>:<base64-value>\r\n
+//! \r\n
+//! ```
+//!
+//! # Signed Protocol Format (STREAMING-AWS4-HMAC-SHA256-PAYLOAD-TRAILER)
+//!
+//! ```text
+//! <hex-chunk-size>;chunk-signature=<sig>\r\n
+//! <chunk-data>\r\n
+//! ...
+//! 0;chunk-signature=<final-sig>\r\n
+//! x-amz-checksum-<algorithm>:<base64-value>\r\n
+//! x-amz-trailer-signature:<trailer-sig>\r\n
+//! \r\n
+//! ```
+//!
+//! # Wire Format vs Canonical Form
+//!
+//! **Important**: There are two different line ending conventions:
+//!
+//! - **Wire format (HTTP protocol)**: Uses `\r\n` (CRLF) per RFC 9112 (HTTP/1.1)
+//! - **Canonical form (for signing)**: Uses `\n` (LF) per AWS SigV4 spec
+//!
+//! When computing the trailer signature, AWS specifies:
+//! ```text
+//! hash('x-amz-checksum-crc32c:sOO8/Q==\n')  // Note: \n not \r\n
+//! ```
+//!
+//! But the actual bytes sent over HTTP use CRLF line endings.
+//!
+//! Reference: <https://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-streaming-trailers.html>
+
+use crate::s3::signer::{ChunkSigningContext, sign_chunk, sign_trailer};
+use crate::s3::utils::{ChecksumAlgorithm, b64_encode, sha256_hash};
+use bytes::Bytes;
+use crc_fast::{CrcAlgorithm, Digest as CrcFastDigest};
+use futures_util::Stream;
+#[cfg(feature = "ring")]
+use ring::digest::{Context, SHA256};
+use sha1::{Digest as Sha1Digest, Sha1};
+#[cfg(not(feature = "ring"))]
+use sha2::Sha256;
+use std::pin::Pin;
+use std::sync::Arc;
+use std::task::{Context as TaskContext, Poll};
+
+/// Default chunk size for aws-chunked encoding (64 KB).
+const DEFAULT_CHUNK_SIZE: usize = 64 * 1024;
+
+/// Incremental checksum hasher for streaming computation.
+enum StreamingHasher {
+    Crc32(CrcFastDigest),
+    Crc32c(CrcFastDigest),
+    Crc64nvme(CrcFastDigest),
+    Sha1(Sha1),
+    #[cfg(feature = "ring")]
+    Sha256(Context),
+    #[cfg(not(feature = "ring"))]
+    Sha256(Sha256),
+}
+
+impl StreamingHasher {
+    fn new(algorithm: ChecksumAlgorithm) -> Self {
+        match algorithm {
+            ChecksumAlgorithm::CRC32 => {
+                StreamingHasher::Crc32(CrcFastDigest::new(CrcAlgorithm::Crc32IsoHdlc))
+            }
+            ChecksumAlgorithm::CRC32C => {
+                StreamingHasher::Crc32c(CrcFastDigest::new(CrcAlgorithm::Crc32Iscsi))
+            }
+            ChecksumAlgorithm::CRC64NVME => {
+                StreamingHasher::Crc64nvme(CrcFastDigest::new(CrcAlgorithm::Crc64Nvme))
+            }
+            ChecksumAlgorithm::SHA1 => StreamingHasher::Sha1(Sha1::new()),
+            #[cfg(feature = "ring")]
+            ChecksumAlgorithm::SHA256 => StreamingHasher::Sha256(Context::new(&SHA256)),
+            #[cfg(not(feature = "ring"))]
+            ChecksumAlgorithm::SHA256 => StreamingHasher::Sha256(Sha256::new()),
+        }
+    }
+
+    fn update(&mut self, data: &[u8]) {
+        match self {
+            StreamingHasher::Crc32(d) => d.update(data),
+            StreamingHasher::Crc32c(d) => d.update(data),
+            StreamingHasher::Crc64nvme(d) => d.update(data),
+            StreamingHasher::Sha1(h) => h.update(data),
+            #[cfg(feature = "ring")]
+            StreamingHasher::Sha256(ctx) => ctx.update(data),
+            #[cfg(not(feature = "ring"))]
+            StreamingHasher::Sha256(h) => h.update(data),
+        }
+    }
+
+    fn finalize(self) -> String {
+        match self {
+            // crc-fast returns u64; CRC32 variants need cast to u32
+            StreamingHasher::Crc32(d) => b64_encode((d.finalize() as u32).to_be_bytes()),
+            StreamingHasher::Crc32c(d) => b64_encode((d.finalize() as u32).to_be_bytes()),
+            StreamingHasher::Crc64nvme(d) => b64_encode(d.finalize().to_be_bytes()),
+            StreamingHasher::Sha1(h) => {
+                let result = h.finalize();
+                b64_encode(&result[..])
+            }
+            #[cfg(feature = "ring")]
+            StreamingHasher::Sha256(ctx) => b64_encode(ctx.finish().as_ref()),
+            #[cfg(not(feature = "ring"))]
+            StreamingHasher::Sha256(h) => {
+                let result = h.finalize();
+                b64_encode(&result[..])
+            }
+        }
+    }
+}
+
+/// State machine for the aws-chunked encoder.
+#[derive(Clone, Copy)]
+enum EncoderState {
+    /// Emitting data chunks
+    Streaming,
+    /// Emitting the final zero-length chunk marker
+    FinalChunk,
+    /// Emitting the trailer with checksum
+    Trailer,
+    /// Done
+    Done,
+}
+
+/// AWS Chunked encoder that wraps data in aws-chunked format with trailing checksum.
+///
+/// This encoder takes input data and produces output in the following format:
+/// ```text
+/// <hex-size>\r\n
+/// <data>\r\n
+/// 0\r\n
+/// x-amz-checksum-<alg>:<base64>\r\n
+/// \r\n
+/// ```
+pub struct AwsChunkedEncoder<S> {
+    inner: S,
+    algorithm: ChecksumAlgorithm,
+    hasher: Option<StreamingHasher>,
+    state: EncoderState,
+}
+
+impl<S> AwsChunkedEncoder<S> {
+    /// Creates a new AWS chunked encoder wrapping the given stream.
+    pub fn new(inner: S, algorithm: ChecksumAlgorithm) -> Self {
+        Self {
+            inner,
+            algorithm,
+            hasher: Some(StreamingHasher::new(algorithm)),
+            state: EncoderState::Streaming,
+        }
+    }
+}
+
+impl<S, E> Stream for AwsChunkedEncoder<S>
+where
+    S: Stream<Item = Result<Bytes, E>> + Unpin,
+{
+    type Item = Result<Bytes, E>;
+
+    fn poll_next(mut self: Pin<&mut Self>, cx: &mut TaskContext<'_>) -> Poll<Option<Self::Item>> {
+        loop {
+            match self.state {
+                EncoderState::Streaming => {
+                    let inner = Pin::new(&mut self.inner);
+                    match inner.poll_next(cx) {
+                        Poll::Ready(Some(Ok(chunk))) => {
+                            if chunk.is_empty() {
+                                continue;
+                            }
+
+                            // Update checksum with raw data
+                            if let Some(ref mut hasher) = self.hasher {
+                                hasher.update(&chunk);
+                            }
+
+                            // Format: <hex-size>\r\n<data>\r\n
+                            let chunk_header = format!("{:x}\r\n", chunk.len());
+                            let mut output =
+                                Vec::with_capacity(chunk_header.len() + chunk.len() + 2);
+                            output.extend_from_slice(chunk_header.as_bytes());
+                            output.extend_from_slice(&chunk);
+                            output.extend_from_slice(b"\r\n");
+
+                            return Poll::Ready(Some(Ok(Bytes::from(output))));
+                        }
+                        Poll::Ready(Some(Err(e))) => {
+                            return Poll::Ready(Some(Err(e)));
+                        }
+                        Poll::Ready(None) => {
+                            // Input stream exhausted, move to final chunk
+                            self.state = EncoderState::FinalChunk;
+                        }
+                        Poll::Pending => {
+                            return Poll::Pending;
+                        }
+                    }
+                }
+
+                EncoderState::FinalChunk => {
+                    // Emit "0\r\n" for the final zero-length chunk
+                    self.state = EncoderState::Trailer;
+                    return Poll::Ready(Some(Ok(Bytes::from_static(b"0\r\n"))));
+                }
+
+                EncoderState::Trailer => {
+                    // Compute and emit the trailer
+                    let hasher = self.hasher.take().expect("hasher should exist");
+                    let checksum_value = hasher.finalize();
+                    let trailer = format!(
+                        "{}:{}\r\n\r\n",
+                        self.algorithm.header_name(),
+                        checksum_value
+                    );
+
+                    self.state = EncoderState::Done;
+                    return Poll::Ready(Some(Ok(Bytes::from(trailer))));
+                }
+
+                EncoderState::Done => {
+                    return Poll::Ready(None);
+                }
+            }
+        }
+    }
+}
+
+/// Calculates the encoded length for aws-chunked format.
+///
+/// For a given content length and chunk size, returns the total encoded length
+/// including all chunk headers, the final zero-length chunk, and the trailer.
+pub fn calculate_encoded_length(
+    content_length: u64,
+    chunk_size: usize,
+    algorithm: ChecksumAlgorithm,
+) -> u64 {
+    let chunk_size = chunk_size as u64;
+
+    // Number of full chunks
+    let full_chunks = content_length / chunk_size;
+    // Size of the last partial chunk (0 if content divides evenly)
+    let last_chunk_size = content_length % chunk_size;
+    let has_partial = if last_chunk_size > 0 { 1 } else { 0 };
+
+    // Each chunk: "<hex-size>\r\n<data>\r\n"
+    // hex-size length varies based on chunk size
+    let hex_len_full = format!("{:x}", chunk_size).len() as u64;
+    let hex_len_partial = if last_chunk_size > 0 {
+        format!("{:x}", last_chunk_size).len() as u64
+    } else {
+        0
+    };
+
+    // Full chunks overhead: hex_len + 2 (\r\n) + chunk_size + 2 (\r\n)
+    let full_chunk_overhead = full_chunks * (hex_len_full + 2 + chunk_size + 2);
+
+    // Partial chunk overhead (if any)
+    let partial_chunk_overhead = if has_partial > 0 {
+        hex_len_partial + 2 + last_chunk_size + 2
+    } else {
+        0
+    };
+
+    // Final chunk: "0\r\n"
+    let final_chunk = 3;
+
+    // Trailer: "x-amz-checksum-<alg>:<base64>\r\n\r\n"
+    // Header name length + ":" + base64 checksum length + "\r\n\r\n"
+    let trailer_header_len = algorithm.header_name().len() as u64;
+    let checksum_b64_len = match algorithm {
+        ChecksumAlgorithm::CRC32 | ChecksumAlgorithm::CRC32C => 8, // 4 bytes -> 8 chars base64
+        ChecksumAlgorithm::CRC64NVME => 12,                        // 8 bytes -> 12 chars base64
+        ChecksumAlgorithm::SHA1 => 28,                             // 20 bytes -> 28 chars base64
+        ChecksumAlgorithm::SHA256 => 44,                           // 32 bytes -> 44 chars base64
+    };
+    let trailer_len = trailer_header_len + 1 + checksum_b64_len + 4; // +1 for ":", +4 for "\r\n\r\n"
+
+    full_chunk_overhead + partial_chunk_overhead + final_chunk + trailer_len
+}
+
+/// Returns the default chunk size for aws-chunked encoding.
+pub fn default_chunk_size() -> usize {
+    DEFAULT_CHUNK_SIZE
+}
+
+// ===========================
+// Signed AWS Chunked Encoder
+// ===========================
+
+/// State machine for the signed aws-chunked encoder.
+#[derive(Clone, Copy)]
+enum SignedEncoderState {
+    /// Emitting signed data chunks
+    Streaming,
+    /// Emitting the final zero-length chunk with signature
+    FinalChunk,
+    /// Emitting the checksum trailer header
+    Trailer,
+    /// Emitting the trailer signature
+    TrailerSignature,
+    /// Done
+    Done,
+}
+
+/// AWS Chunked encoder with chunk signing for STREAMING-AWS4-HMAC-SHA256-PAYLOAD-TRAILER.
+///
+/// Each chunk is signed using the AWS Signature V4 chunk signing algorithm.
+/// The final trailer is also signed with a trailer signature.
+///
+/// # Wire Format
+///
+/// ```text
+/// <hex-size>;chunk-signature=<sig>\r\n
+/// <data>\r\n
+/// 0;chunk-signature=<final-sig>\r\n
+/// x-amz-checksum-<alg>:<base64>\r\n
+/// x-amz-trailer-signature:<trailer-sig>\r\n
+/// \r\n
+/// ```
+pub struct SignedAwsChunkedEncoder<S> {
+    inner: S,
+    algorithm: ChecksumAlgorithm,
+    hasher: Option<StreamingHasher>,
+    state: SignedEncoderState,
+
+    // Signing context
+    signing_key: Arc<[u8]>,
+    date_time: String,
+    scope: String,
+
+    // Signature chain - each chunk's signature becomes the previous for the next
+    current_signature: String,
+
+    // Store the checksum value for trailer signature computation
+    checksum_value: Option<String>,
+}
+
+impl<S> SignedAwsChunkedEncoder<S> {
+    /// Creates a new signed AWS chunked encoder wrapping the given stream.
+    ///
+    /// # Arguments
+    /// * `inner` - The underlying data stream
+    /// * `algorithm` - The checksum algorithm to use
+    /// * `context` - The chunk signing context from request signing
+    pub fn new(inner: S, algorithm: ChecksumAlgorithm, context: ChunkSigningContext) -> Self {
+        Self {
+            inner,
+            algorithm,
+            hasher: Some(StreamingHasher::new(algorithm)),
+            state: SignedEncoderState::Streaming,
+            signing_key: context.signing_key,
+            date_time: context.date_time,
+            scope: context.scope,
+            current_signature: context.seed_signature,
+            checksum_value: None,
+        }
+    }
+
+    /// Signs a chunk and returns the signature.
+    fn sign_chunk_data(&mut self, chunk_hash: &str) -> String {
+        let signature = sign_chunk(
+            &self.signing_key,
+            &self.date_time,
+            &self.scope,
+            &self.current_signature,
+            chunk_hash,
+        );
+        self.current_signature = signature.clone();
+        signature
+    }
+}
+
+impl<S, E> Stream for SignedAwsChunkedEncoder<S>
+where
+    S: Stream<Item = Result<Bytes, E>> + Unpin,
+{
+    type Item = Result<Bytes, E>;
+
+    fn poll_next(mut self: Pin<&mut Self>, cx: &mut TaskContext<'_>) -> Poll<Option<Self::Item>> {
+        loop {
+            match self.state {
+                SignedEncoderState::Streaming => {
+                    let inner = Pin::new(&mut self.inner);
+                    match inner.poll_next(cx) {
+                        Poll::Ready(Some(Ok(chunk))) => {
+                            if chunk.is_empty() {
+                                continue;
+                            }
+
+                            // Update checksum hasher with raw data
+                            if let Some(ref mut hasher) = self.hasher {
+                                hasher.update(&chunk);
+                            }
+
+                            // Compute SHA256 hash of chunk data for signing
+                            let chunk_hash = sha256_hash(&chunk);
+
+                            // Sign the chunk
+                            let signature = self.sign_chunk_data(&chunk_hash);
+
+                            // Format: <hex-size>;chunk-signature=<sig>\r\n<data>\r\n
+                            let chunk_header =
+                                format!("{:x};chunk-signature={}\r\n", chunk.len(), signature);
+                            let mut output =
+                                Vec::with_capacity(chunk_header.len() + chunk.len() + 2);
+                            output.extend_from_slice(chunk_header.as_bytes());
+                            output.extend_from_slice(&chunk);
+                            output.extend_from_slice(b"\r\n");
+
+                            return Poll::Ready(Some(Ok(Bytes::from(output))));
+                        }
+                        Poll::Ready(Some(Err(e))) => {
+                            return Poll::Ready(Some(Err(e)));
+                        }
+                        Poll::Ready(None) => {
+                            // Input stream exhausted, move to final chunk
+                            self.state = SignedEncoderState::FinalChunk;
+                        }
+                        Poll::Pending => {
+                            return Poll::Pending;
+                        }
+                    }
+                }
+
+                SignedEncoderState::FinalChunk => {
+                    // Sign the empty chunk (SHA256 of empty string)
+                    const EMPTY_SHA256: &str =
+                        "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855";
+                    let signature = self.sign_chunk_data(EMPTY_SHA256);
+
+                    // Emit "0;chunk-signature=<sig>\r\n"
+                    let final_chunk = format!("0;chunk-signature={}\r\n", signature);
+
+                    self.state = SignedEncoderState::Trailer;
+                    return Poll::Ready(Some(Ok(Bytes::from(final_chunk))));
+                }
+
+                SignedEncoderState::Trailer => {
+                    // Compute and store the checksum value
+                    let hasher = self.hasher.take().expect("hasher should exist");
+                    let checksum_value = hasher.finalize();
+                    self.checksum_value = Some(checksum_value.clone());
+
+                    // Emit the checksum trailer using CRLF (wire format per RFC 9112)
+                    // Note: The canonical form for signing uses LF (\n), but HTTP wire
+                    // format uses CRLF (\r\n). See module docs for details.
+                    let trailer = format!(
+                        "{}:{}\r\n",
+                        self.algorithm.header_name().to_lowercase(),
+                        checksum_value
+                    );
+
+                    self.state = SignedEncoderState::TrailerSignature;
+                    return Poll::Ready(Some(Ok(Bytes::from(trailer))));
+                }
+
+                SignedEncoderState::TrailerSignature => {
+                    // Compute the canonical trailers string for signing.
+                    // IMPORTANT: AWS SigV4 canonical form uses LF (\n), NOT CRLF (\r\n).
+                    // Per AWS docs: hash('x-amz-checksum-crc32c:sOO8/Q==\n')
+                    // This differs from the wire format which uses CRLF.
+                    let checksum_value =
+                        self.checksum_value.as_ref().expect("checksum should exist");
+                    let canonical_trailers = format!(
+                        "{}:{}\n", // LF for canonical form (signing)
+                        self.algorithm.header_name().to_lowercase(),
+                        checksum_value
+                    );
+
+                    // Hash the canonical trailers
+                    let trailers_hash = sha256_hash(canonical_trailers.as_bytes());
+
+                    // Sign the trailer
+                    let trailer_signature = sign_trailer(
+                        &self.signing_key,
+                        &self.date_time,
+                        &self.scope,
+                        &self.current_signature,
+                        &trailers_hash,
+                    );
+
+                    // Emit trailer signature using CRLF (wire format per RFC 9112)
+                    // Final \r\n\r\n marks end of trailer section
+                    let trailer_sig_line =
+                        format!("x-amz-trailer-signature:{}\r\n\r\n", trailer_signature);
+
+                    self.state = SignedEncoderState::Done;
+                    return Poll::Ready(Some(Ok(Bytes::from(trailer_sig_line))));
+                }
+
+                SignedEncoderState::Done => {
+                    return Poll::Ready(None);
+                }
+            }
+        }
+    }
+}
+
+/// Calculates the encoded length for signed aws-chunked format.
+///
+/// For a given content length and chunk size, returns the total encoded length
+/// including all chunk headers with signatures, the final zero-length chunk,
+/// the checksum trailer, and the trailer signature.
+pub fn calculate_signed_encoded_length(
+    content_length: u64,
+    chunk_size: usize,
+    algorithm: ChecksumAlgorithm,
+) -> u64 {
+    let chunk_size = chunk_size as u64;
+
+    // Number of full chunks
+    let full_chunks = content_length / chunk_size;
+    // Size of the last partial chunk (0 if content divides evenly)
+    let last_chunk_size = content_length % chunk_size;
+    let has_partial = if last_chunk_size > 0 { 1 } else { 0 };
+
+    // Each signed chunk: "<hex-size>;chunk-signature=<64-hex>\r\n<data>\r\n"
+    // Signature overhead per chunk: ";chunk-signature=" (17) + 64 hex chars = 81 bytes
+    let signature_overhead: u64 = 81;
+
+    let hex_len_full = format!("{:x}", chunk_size).len() as u64;
+    let hex_len_partial = if last_chunk_size > 0 {
+        format!("{:x}", last_chunk_size).len() as u64
+    } else {
+        0
+    };
+
+    // Full chunks: hex_len + signature_overhead + 2 (\r\n) + chunk_size + 2 (\r\n)
+    let full_chunk_overhead =
+        full_chunks * (hex_len_full + signature_overhead + 2 + chunk_size + 2);
+
+    // Partial chunk (if any)
+    let partial_chunk_overhead = if has_partial > 0 {
+        hex_len_partial + signature_overhead + 2 + last_chunk_size + 2
+    } else {
+        0
+    };
+
+    // Final chunk: "0;chunk-signature=<64-hex>\r\n" = 1 + 81 + 2 = 84
+    let final_chunk = 84;
+
+    // Checksum trailer: "<lowercase-header>:<base64>\r\n"
+    // Header name is lowercase (e.g., "x-amz-checksum-crc32")
+    let trailer_header_len = algorithm.header_name().to_lowercase().len() as u64;
+    let checksum_b64_len = match algorithm {
+        ChecksumAlgorithm::CRC32 | ChecksumAlgorithm::CRC32C => 8,
+        ChecksumAlgorithm::CRC64NVME => 12,
+        ChecksumAlgorithm::SHA1 => 28,
+        ChecksumAlgorithm::SHA256 => 44,
+    };
+    let checksum_trailer = trailer_header_len + 1 + checksum_b64_len + 2; // +1 for ":", +2 for "\r\n"
+
+    // Trailer signature: "x-amz-trailer-signature:<64-hex>\r\n\r\n"
+    // = 24 + 64 + 4 = 92 bytes
+    let trailer_signature = 92;
+
+    full_chunk_overhead
+        + partial_chunk_overhead
+        + final_chunk
+        + checksum_trailer
+        + trailer_signature
+}
+
+// ===========================
+// Rechunking Stream Wrapper
+// ===========================
+
+/// A stream wrapper that re-chunks incoming data to a fixed chunk size.
+///
+/// This ensures that the actual chunks produced match the chunk size assumed
+/// by `calculate_encoded_length` and `calculate_signed_encoded_length`,
+/// preventing Content-Length mismatches when the input stream produces
+/// differently-sized chunks.
+pub struct RechunkingStream<S> {
+    inner: S,
+    chunk_size: usize,
+    buffer: Vec<u8>,
+    done: bool,
+}
+
+impl<S> RechunkingStream<S> {
+    /// Creates a new rechunking stream wrapper.
+    ///
+    /// The wrapper buffers incoming data and emits chunks of exactly `chunk_size` bytes,
+    /// except for the final chunk which may be smaller.
+    pub fn new(inner: S, chunk_size: usize) -> Self {
+        Self {
+            inner,
+            chunk_size,
+            buffer: Vec::with_capacity(chunk_size),
+            done: false,
+        }
+    }
+
+    /// Creates a new rechunking stream with the default chunk size (64 KB).
+    pub fn with_default_chunk_size(inner: S) -> Self {
+        Self::new(inner, DEFAULT_CHUNK_SIZE)
+    }
+}
+
+impl<S, E> Stream for RechunkingStream<S>
+where
+    S: Stream<Item = Result<Bytes, E>> + Unpin,
+{
+    type Item = Result<Bytes, E>;
+
+    fn poll_next(mut self: Pin<&mut Self>, cx: &mut TaskContext<'_>) -> Poll<Option<Self::Item>> {
+        let chunk_size = self.chunk_size;
+
+        if self.done && self.buffer.is_empty() {
+            return Poll::Ready(None);
+        }
+
+        // If we already have a full chunk buffered, emit it
+        if self.buffer.len() >= chunk_size {
+            let chunk: Vec<u8> = self.buffer.drain(..chunk_size).collect();
+            return Poll::Ready(Some(Ok(Bytes::from(chunk))));
+        }
+
+        // Try to fill the buffer from the inner stream
+        loop {
+            if self.done {
+                // Inner stream exhausted, emit remaining buffer as final chunk
+                if self.buffer.is_empty() {
+                    return Poll::Ready(None);
+                }
+                let remaining = std::mem::take(&mut self.buffer);
+                return Poll::Ready(Some(Ok(Bytes::from(remaining))));
+            }
+
+            let inner = Pin::new(&mut self.inner);
+            match inner.poll_next(cx) {
+                Poll::Ready(Some(Ok(chunk))) => {
+                    if chunk.is_empty() {
+                        continue;
+                    }
+
+                    self.buffer.extend_from_slice(&chunk);
+
+                    // If we now have enough for a full chunk, emit it
+                    if self.buffer.len() >= chunk_size {
+                        let chunk: Vec<u8> = self.buffer.drain(..chunk_size).collect();
+                        return Poll::Ready(Some(Ok(Bytes::from(chunk))));
+                    }
+                    // Otherwise continue buffering
+                }
+                Poll::Ready(Some(Err(e))) => {
+                    return Poll::Ready(Some(Err(e)));
+                }
+                Poll::Ready(None) => {
+                    self.done = true;
+                    // Loop will handle emitting remaining buffer
+                }
+                Poll::Pending => {
+                    return Poll::Pending;
+                }
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use futures_util::StreamExt;
+
+    #[tokio::test]
+    async fn test_aws_chunked_encoder_simple() {
+        let data = Bytes::from("Hello, World!");
+        // Use iter instead of once - iter produces an Unpin stream
+        let stream = futures_util::stream::iter(vec![Ok::<_, std::io::Error>(data.clone())]);
+
+        let mut encoder = AwsChunkedEncoder::new(stream, ChecksumAlgorithm::CRC32);
+        let mut output = Vec::new();
+
+        while let Some(chunk) = encoder.next().await {
+            output.extend_from_slice(&chunk.unwrap());
+        }
+
+        let output_str = String::from_utf8(output).unwrap();
+
+        // Should start with hex size of "Hello, World!" (13 bytes = 'd')
+        assert!(output_str.starts_with("d\r\n"));
+        // Should contain the data
+        assert!(output_str.contains("Hello, World!"));
+        // Should end with trailer (header name is mixed-case per S3 spec)
+        assert!(output_str.contains("X-Amz-Checksum-CRC32:"));
+        assert!(output_str.ends_with("\r\n\r\n"));
+        // Should have zero-length final chunk
+        assert!(output_str.contains("\r\n0\r\n"));
+    }
+
+    #[tokio::test]
+    async fn test_aws_chunked_encoder_multiple_chunks() {
+        let chunks = vec![
+            Ok::<_, std::io::Error>(Bytes::from("Hello, ")),
+            Ok(Bytes::from("World!")),
+        ];
+        let stream = futures_util::stream::iter(chunks);
+
+        let mut encoder = AwsChunkedEncoder::new(stream, ChecksumAlgorithm::CRC64NVME);
+        let mut output = Vec::new();
+
+        while let Some(chunk) = encoder.next().await {
+            output.extend_from_slice(&chunk.unwrap());
+        }
+
+        let output_str = String::from_utf8(output).unwrap();
+
+        // Should have two chunk headers
+        assert!(output_str.starts_with("7\r\n")); // "Hello, " is 7 bytes
+        assert!(output_str.contains("6\r\n")); // "World!" is 6 bytes
+        assert!(output_str.contains("X-Amz-Checksum-CRC64NVME:"));
+    }
+
+    #[test]
+    fn test_calculate_encoded_length() {
+        // Simple case: 100 bytes, 64KB chunks
+        let len = calculate_encoded_length(100, 64 * 1024, ChecksumAlgorithm::CRC32);
+        // 100 bytes fits in one chunk: "64\r\n" (4) + 100 + "\r\n" (2) + "0\r\n" (3) + trailer
+        // "64" is hex for 100, which is "64" (2 chars)
+        // trailer: "x-amz-checksum-crc32:" (21) + 8 (base64) + "\r\n\r\n" (4) = 33
+        // Total: 2 + 2 + 100 + 2 + 3 + 33 = 142
+        assert!(len > 100); // Should be larger than raw content
+    }
+
+    // ===========================
+    // Signed Encoder Tests
+    // ===========================
+
+    fn test_signing_context() -> ChunkSigningContext {
+        ChunkSigningContext {
+            signing_key: Arc::from(vec![
+                // Pre-computed signing key for test credentials
+                0x98, 0xf1, 0xd8, 0x89, 0xfe, 0xc4, 0xf4, 0x42, 0x1a, 0xdc, 0x52, 0x2b, 0xab, 0x0c,
+                0xe1, 0xf8, 0x2c, 0x6c, 0x4e, 0x4e, 0xc3, 0x9a, 0xe1, 0xf6, 0xcc, 0xf2, 0x0e, 0x8f,
+                0x40, 0x89, 0x45, 0x65,
+            ]),
+            date_time: "20130524T000000Z".to_string(),
+            scope: "20130524/us-east-1/s3/aws4_request".to_string(),
+            seed_signature: "4f232c4386841ef735655705268965c44a0e4690baa4adea153f7db9fa80a0a9"
+                .to_string(),
+        }
+    }
+
+    #[tokio::test]
+    async fn test_signed_encoder_simple() {
+        let data = Bytes::from("Hello, World!");
+        let stream = futures_util::stream::iter(vec![Ok::<_, std::io::Error>(data)]);
+
+        let context = test_signing_context();
+        let mut encoder = SignedAwsChunkedEncoder::new(stream, ChecksumAlgorithm::CRC32, context);
+        let mut output = Vec::new();
+
+        while let Some(chunk) = encoder.next().await {
+            output.extend_from_slice(&chunk.unwrap());
+        }
+
+        let output_str = String::from_utf8(output).unwrap();
+
+        // Should start with hex size and chunk-signature
+        assert!(output_str.starts_with("d;chunk-signature="));
+        // Should contain the data
+        assert!(output_str.contains("Hello, World!"));
+        // Should have final chunk with signature
+        assert!(output_str.contains("0;chunk-signature="));
+        // Should have checksum trailer (lowercase)
+        assert!(output_str.contains("x-amz-checksum-crc32:"));
+        // Should have trailer signature
+        assert!(output_str.contains("x-amz-trailer-signature:"));
+        // Should end with \r\n\r\n
+        assert!(output_str.ends_with("\r\n\r\n"));
+    }
+
+    #[tokio::test]
+    async fn test_signed_encoder_multiple_chunks() {
+        let chunks = vec![
+            Ok::<_, std::io::Error>(Bytes::from("Hello, ")),
+            Ok(Bytes::from("World!")),
+        ];
+        let stream = futures_util::stream::iter(chunks);
+
+        let context = test_signing_context();
+        let mut encoder = SignedAwsChunkedEncoder::new(stream, ChecksumAlgorithm::CRC32C, context);
+        let mut output = Vec::new();
+
+        while let Some(chunk) = encoder.next().await {
+            output.extend_from_slice(&chunk.unwrap());
+        }
+
+        let output_str = String::from_utf8(output).unwrap();
+
+        // Should have two chunk signatures (different signatures due to chaining)
+        let sig_count = output_str.matches(";chunk-signature=").count();
+        assert_eq!(sig_count, 3); // 2 data chunks + 1 final chunk
+
+        // Should have checksum trailer
+        assert!(output_str.contains("x-amz-checksum-crc32c:"));
+        // Should have trailer signature
+        assert!(output_str.contains("x-amz-trailer-signature:"));
+    }
+
+    #[tokio::test]
+    async fn test_signed_encoder_signature_is_64_hex_chars() {
+        let data = Bytes::from("test");
+        let stream = futures_util::stream::iter(vec![Ok::<_, std::io::Error>(data)]);
+
+        let context = test_signing_context();
+        let mut encoder = SignedAwsChunkedEncoder::new(stream, ChecksumAlgorithm::CRC32, context);
+        let mut output = Vec::new();
+
+        while let Some(chunk) = encoder.next().await {
+            output.extend_from_slice(&chunk.unwrap());
+        }
+
+        let output_str = String::from_utf8(output).unwrap();
+
+        // Extract signatures and verify they're 64 hex chars
+        for sig_match in output_str.match_indices(";chunk-signature=") {
+            let start = sig_match.0 + sig_match.1.len();
+            let sig = &output_str[start..start + 64];
+            assert!(
+                sig.chars().all(|c| c.is_ascii_hexdigit()),
+                "Signature should be hex: {}",
+                sig
+            );
+        }
+
+        // Also check trailer signature
+        let trailer_sig_start = output_str.find("x-amz-trailer-signature:").unwrap() + 24;
+        let trailer_sig = &output_str[trailer_sig_start..trailer_sig_start + 64];
+        assert!(
+            trailer_sig.chars().all(|c| c.is_ascii_hexdigit()),
+            "Trailer signature should be hex: {}",
+            trailer_sig
+        );
+    }
+
+    #[test]
+    fn test_calculate_signed_encoded_length() {
+        // 100 bytes, 64KB chunks
+        let len = calculate_signed_encoded_length(100, 64 * 1024, ChecksumAlgorithm::CRC32);
+
+        // Should be larger than unsigned (due to signature overhead)
+        let unsigned_len = calculate_encoded_length(100, 64 * 1024, ChecksumAlgorithm::CRC32);
+        assert!(
+            len > unsigned_len,
+            "Signed length {} should be > unsigned length {}",
+            len,
+            unsigned_len
+        );
+    }
+
+    #[test]
+    fn test_calculate_signed_encoded_length_multiple_chunks() {
+        // 200KB with 64KB chunks = 3 full chunks + 1 partial + final
+        let content_len = 200 * 1024;
+        let chunk_size = 64 * 1024;
+        let len =
+            calculate_signed_encoded_length(content_len, chunk_size, ChecksumAlgorithm::SHA256);
+
+        // Should include all overhead
+        assert!(len > content_len);
+
+        // Calculate expected: signature overhead per chunk is 81 bytes
+        // Plus final chunk (84), checksum trailer, trailer signature (92)
+    }
+
+    // ===========================
+    // RechunkingStream Tests
+    // ===========================
+
+    #[tokio::test]
+    async fn test_rechunking_stream_combines_small_chunks() {
+        // Create many small 1KB chunks
+        let chunk_size = 1024;
+        let num_chunks = 10;
+        let chunks: Vec<Result<Bytes, std::io::Error>> = (0..num_chunks)
+            .map(|i| Ok(Bytes::from(vec![i as u8; chunk_size])))
+            .collect();
+
+        let stream = futures_util::stream::iter(chunks);
+        let mut rechunker = RechunkingStream::new(stream, 4096); // 4KB target
+
+        let mut output_chunks = Vec::new();
+        while let Some(chunk) = rechunker.next().await {
+            output_chunks.push(chunk.unwrap());
+        }
+
+        // 10 x 1KB = 10KB, rechunked to 4KB = 2 full + 1 partial (2KB)
+        assert_eq!(output_chunks.len(), 3);
+        assert_eq!(output_chunks[0].len(), 4096);
+        assert_eq!(output_chunks[1].len(), 4096);
+        assert_eq!(output_chunks[2].len(), 2048);
+
+        // Total bytes preserved
+        let total: usize = output_chunks.iter().map(|c| c.len()).sum();
+        assert_eq!(total, num_chunks * chunk_size);
+    }
+
+    #[tokio::test]
+    async fn test_rechunking_stream_passes_large_chunks() {
+        // Single chunk larger than target size
+        let data = Bytes::from(vec![42u8; 10000]);
+        let stream = futures_util::stream::iter(vec![Ok::<_, std::io::Error>(data)]);
+
+        let mut rechunker = RechunkingStream::new(stream, 4096);
+
+        let mut output_chunks = Vec::new();
+        while let Some(chunk) = rechunker.next().await {
+            output_chunks.push(chunk.unwrap());
+        }
+
+        // 10000 bytes / 4096 = 2 full + 1 partial (1808)
+        assert_eq!(output_chunks.len(), 3);
+        assert_eq!(output_chunks[0].len(), 4096);
+        assert_eq!(output_chunks[1].len(), 4096);
+        assert_eq!(output_chunks[2].len(), 1808);
+    }
+
+    #[tokio::test]
+    async fn test_rechunking_stream_exact_multiple() {
+        // Data that divides evenly into chunk size
+        let data = Bytes::from(vec![1u8; 8192]);
+        let stream = futures_util::stream::iter(vec![Ok::<_, std::io::Error>(data)]);
+
+        let mut rechunker = RechunkingStream::new(stream, 4096);
+
+        let mut output_chunks = Vec::new();
+        while let Some(chunk) = rechunker.next().await {
+            output_chunks.push(chunk.unwrap());
+        }
+
+        assert_eq!(output_chunks.len(), 2);
+        assert_eq!(output_chunks[0].len(), 4096);
+        assert_eq!(output_chunks[1].len(), 4096);
+    }
+
+    #[tokio::test]
+    async fn test_rechunking_stream_empty() {
+        let stream = futures_util::stream::iter(Vec::<Result<Bytes, std::io::Error>>::new());
+        let mut rechunker = RechunkingStream::new(stream, 4096);
+
+        let result = rechunker.next().await;
+        assert!(result.is_none());
+    }
+
+    #[tokio::test]
+    async fn test_rechunking_stream_preserves_data() {
+        // Verify data integrity through rechunking
+        let original: Vec<u8> = (0..=255).cycle().take(15000).collect();
+        let chunks: Vec<Result<Bytes, std::io::Error>> = original
+            .chunks(100) // 100-byte input chunks
+            .map(|c| Ok(Bytes::copy_from_slice(c)))
+            .collect();
+
+        let stream = futures_util::stream::iter(chunks);
+        let mut rechunker = RechunkingStream::new(stream, 4096);
+
+        let mut output = Vec::new();
+        while let Some(chunk) = rechunker.next().await {
+            output.extend_from_slice(&chunk.unwrap());
+        }
+
+        assert_eq!(output, original);
+    }
+}

src/s3/builders/append_object.rs

@@ -26,7 +26,9 @@ use crate::s3::response_traits::HasObjectSize;
 use crate::s3::segmented_bytes::SegmentedBytes;
 use crate::s3::sse::Sse;
 use crate::s3::types::{S3Api, S3Request, ToS3Request};
-use crate::s3::utils::{check_bucket_name, check_object_name, check_sse};
+use crate::s3::utils::{
+    ChecksumAlgorithm, check_bucket_name, check_object_name, check_sse, compute_checksum_sb,
+};
 use http::Method;
 use std::sync::Arc;
 use typed_builder::TypedBuilder;
@@ -64,6 +66,14 @@ pub struct AppendObject {
     /// Value of `x-amz-write-offset-bytes`.
     #[builder(!default)] // force required
     offset_bytes: u64,
+
+    /// Optional checksum algorithm for data integrity verification during append.
+    ///
+    /// When specified, computes a checksum of the appended data using the selected algorithm
+    /// (CRC32, CRC32C, SHA1, SHA256, or CRC64NVME). The checksum is sent with the append
+    /// operation and verified by the server.
+    #[builder(default, setter(into))]
+    checksum_algorithm: Option<ChecksumAlgorithm>,
 }
 
 impl S3Api for AppendObject {
@@ -83,6 +93,7 @@ pub type AppendObjectBldr = AppendObjectBuilder<(
     (),
     (Arc<SegmentedBytes>,),
     (u64,),
+    (),
 )>;
 
 impl ToS3Request for AppendObject {
@@ -94,6 +105,21 @@ impl ToS3Request for AppendObject {
         let mut headers: Multimap = self.extra_headers.unwrap_or_default();
         headers.add(X_AMZ_WRITE_OFFSET_BYTES, self.offset_bytes.to_string());
 
+        if let Some(algorithm) = self.checksum_algorithm {
+            let checksum_value = compute_checksum_sb(algorithm, &self.data);
+            headers.add(X_AMZ_CHECKSUM_ALGORITHM, algorithm.as_str().to_string());
+
+            match algorithm {
+                ChecksumAlgorithm::CRC32 => headers.add(X_AMZ_CHECKSUM_CRC32, checksum_value),
+                ChecksumAlgorithm::CRC32C => headers.add(X_AMZ_CHECKSUM_CRC32C, checksum_value),
+                ChecksumAlgorithm::SHA1 => headers.add(X_AMZ_CHECKSUM_SHA1, checksum_value),
+                ChecksumAlgorithm::SHA256 => headers.add(X_AMZ_CHECKSUM_SHA256, checksum_value),
+                ChecksumAlgorithm::CRC64NVME => {
+                    headers.add(X_AMZ_CHECKSUM_CRC64NVME, checksum_value)
+                }
+            }
+        }
+
         Ok(S3Request::builder()
             .client(self.client)
             .method(Method::PUT)
@@ -144,6 +170,13 @@ pub struct AppendObjectContent {
     /// Value of `x-amz-write-offset-bytes`.
     #[builder(default)]
     offset_bytes: u64,
+    /// Optional checksum algorithm for data integrity verification during append.
+    ///
+    /// When specified, computes checksums for appended data using the selected algorithm
+    /// (CRC32, CRC32C, SHA1, SHA256, or CRC64NVME). The checksum is computed for each
+    /// chunk and sent with the append operation.
+    #[builder(default, setter(into))]
+    checksum_algorithm: Option<ChecksumAlgorithm>,
 }
 
 /// Builder type for [`AppendObjectContent`] that is returned by [`MinioClient::append_object_content`](crate::s3::client::MinioClient::append_object_content).
@@ -162,6 +195,7 @@ pub type AppendObjectContentBldr = AppendObjectContentBuilder<(
     (),
     (),
     (),
+    (),
 )>;
 
 impl AppendObjectContent {
@@ -229,6 +263,7 @@ impl AppendObjectContent {
                 offset_bytes: current_file_size,
                 sse: self.sse,
                 data: Arc::new(seg_bytes),
+                checksum_algorithm: self.checksum_algorithm,
             };
             ao.send().await
         } else if let Some(expected) = object_size.value()
@@ -296,6 +331,7 @@ impl AppendObjectContent {
                 sse: self.sse.clone(),
                 data: Arc::new(part_content),
                 offset_bytes: next_offset_bytes,
+                checksum_algorithm: self.checksum_algorithm,
             };
             let resp: AppendObjectResponse = append_object.send().await?;
             //println!("AppendObjectResponse: object_size={:?}", resp.object_size);

src/s3/builders/copy_object.rs

@@ -23,12 +23,13 @@ use crate::s3::response::{
     CopyObjectInternalResponse, CopyObjectResponse, CreateMultipartUploadResponse,
     StatObjectResponse, UploadPartCopyResponse,
 };
+use crate::s3::response_traits::HasChecksumHeaders;
 use crate::s3::response_traits::HasEtagFromBody;
 use crate::s3::sse::{Sse, SseCustomerKey};
 use crate::s3::types::{Directive, PartInfo, Retention, S3Api, S3Request, ToS3Request};
 use crate::s3::utils::{
-    UtcTime, check_bucket_name, check_object_name, check_sse, check_ssec, to_http_header_value,
+    ChecksumAlgorithm, UtcTime, check_bucket_name, check_object_name, check_sse, check_ssec,
-    to_iso8601utc, url_encode,
+    to_http_header_value, to_iso8601utc, url_encode,
 };
 use async_recursion::async_recursion;
 use http::Method;
@@ -59,6 +60,13 @@ pub struct UploadPartCopy {
     part_number: u16,
     #[builder(default)]
     headers: Multimap,
+    /// Optional checksum algorithm for data integrity verification during part copy.
+    ///
+    /// When specified, the server computes a checksum of the copied part data using
+    /// this algorithm. Use the same algorithm for all parts in a multipart upload.
+    /// Supported algorithms: CRC32, CRC32C, SHA1, SHA256, CRC64NVME.
+    #[builder(default, setter(into))]
+    checksum_algorithm: Option<crate::s3::utils::ChecksumAlgorithm>,
 }
 
 impl S3Api for UploadPartCopy {
@@ -78,6 +86,7 @@ pub type UploadPartCopyBldr = UploadPartCopyBuilder<(
     (String,),
     (),
     (),
+    (),
 )>;
 
 impl ToS3Request for UploadPartCopy {
@@ -100,6 +109,10 @@ impl ToS3Request for UploadPartCopy {
         let mut headers: Multimap = self.extra_headers.unwrap_or_default();
         headers.add_multimap(self.headers);
 
+        if let Some(algorithm) = self.checksum_algorithm {
+            headers.add(X_AMZ_CHECKSUM_ALGORITHM, algorithm.as_str().to_string());
+        }
+
         let mut query_params: Multimap = self.extra_query_params.unwrap_or_default();
         {
             query_params.add("partNumber", self.part_number.to_string());
@@ -150,6 +163,8 @@ pub struct CopyObjectInternal {
     metadata_directive: Option<Directive>,
     #[builder(default, setter(into))]
     tagging_directive: Option<Directive>,
+    #[builder(default, setter(into))]
+    checksum_algorithm: Option<crate::s3::utils::ChecksumAlgorithm>,
 }
 
 impl S3Api for CopyObjectInternal {
@@ -175,6 +190,7 @@ pub type CopyObjectInternalBldr = CopyObjectInternalBuilder<(
     (),
     (),
     (),
+    (),
 )>;
 
 impl ToS3Request for CopyObjectInternal {
@@ -261,6 +277,10 @@ impl ToS3Request for CopyObjectInternal {
             if let Some(v) = self.source.ssec {
                 headers.add_multimap(v.copy_headers());
             }
+
+            if let Some(algorithm) = self.checksum_algorithm {
+                headers.add(X_AMZ_CHECKSUM_ALGORITHM, algorithm.as_str().to_string());
+            }
         };
 
         Ok(S3Request::builder()
@@ -310,6 +330,13 @@ pub struct CopyObject {
     metadata_directive: Option<Directive>,
     #[builder(default, setter(into))]
     tagging_directive: Option<Directive>,
+    /// Optional checksum algorithm for data integrity verification during copy.
+    ///
+    /// When specified, the server computes a checksum of the destination object using
+    /// this algorithm during the copy operation. Supported algorithms: CRC32, CRC32C,
+    /// SHA1, SHA256, CRC64NVME. The checksum value is included in response headers for verification.
+    #[builder(default, setter(into))]
+    checksum_algorithm: Option<crate::s3::utils::ChecksumAlgorithm>,
 }
 
 /// Builder type for [`CopyObject`] that is returned by [`MinioClient::copy_object`](crate::s3::client::MinioClient::copy_object).
@@ -331,6 +358,7 @@ pub type CopyObjectBldr = CopyObjectBuilder<(
     (),
     (),
     (),
+    (),
 )>;
 
 impl CopyObject {
@@ -434,6 +462,7 @@ impl CopyObject {
                 .source(self.source)
                 .metadata_directive(self.metadata_directive)
                 .tagging_directive(self.tagging_directive)
+                .checksum_algorithm(self.checksum_algorithm)
                 .build()
                 .send()
                 .await?;
@@ -472,6 +501,8 @@ pub struct ComposeObjectInternal {
     legal_hold: bool,
     #[builder(default)]
     sources: Vec<ComposeSource>,
+    #[builder(default, setter(into))]
+    checksum_algorithm: Option<ChecksumAlgorithm>,
 }
 
 /// Builder type for [`ComposeObjectInternal`] that is returned by `compose_object_internal` method.
@@ -491,6 +522,7 @@ pub type ComposeObjectInternalBldr = ComposeObjectInternalBuilder<(
     (),
     (),
     (),
+    (),
 )>;
 
 impl ComposeObjectInternal {
@@ -523,10 +555,10 @@ impl ComposeObjectInternal {
                 .legal_hold(self.legal_hold)
                 .source(
                     CopySource::builder()
-                        .bucket(&self.bucket)
+                        .bucket(&sources[0].bucket)
-                        .object(&self.object)
+                        .object(&sources[0].object)
                         .build(),
-                ) // TODO redundant use of bucket and object
+                )
                 .build()
                 .send()
                 .await
@@ -554,6 +586,7 @@ impl ComposeObjectInternal {
                 .extra_query_params(self.extra_query_params.clone())
                 .region(self.region.clone())
                 .extra_headers(Some(headers))
+                .checksum_algorithm(self.checksum_algorithm)
                 .build()
                 .send()
                 .await
@@ -612,6 +645,7 @@ impl ComposeObjectInternal {
                         .region(self.region.clone())
                         .part_number(part_number)
                         .headers(headers)
+                        .checksum_algorithm(self.checksum_algorithm)
                         .build()
                         .send()
                         .await
@@ -625,11 +659,10 @@ impl ComposeObjectInternal {
                         Err(e) => return (Err(e.into()), upload_id),
                     };
 
-                    parts.push(PartInfo {
+                    let checksum = self
-                        number: part_number,
+                        .checksum_algorithm
-                        etag,
+                        .and_then(|alg| resp.get_checksum(alg).map(|v| (alg, v)));
-                        size,
+                    parts.push(PartInfo::new(part_number, etag, size, checksum));
-                    });
                 } else {
                     let part_ranges = calculate_part_ranges(offset, size, MAX_PART_SIZE);
                     for (part_offset, length) in part_ranges {
@@ -648,6 +681,7 @@ impl ComposeObjectInternal {
                             .region(self.region.clone())
                             .part_number(part_number)
                             .headers(headers_copy)
+                            .checksum_algorithm(self.checksum_algorithm)
                             .build()
                             .send()
                             .await
@@ -661,11 +695,10 @@ impl ComposeObjectInternal {
                             Err(e) => return (Err(e.into()), upload_id),
                         };
 
-                        parts.push(PartInfo {
+                        let checksum = self
-                            number: part_number,
+                            .checksum_algorithm
-                            etag,
+                            .and_then(|alg| resp.get_checksum(alg).map(|v| (alg, v)));
-                            size: length,
+                        parts.push(PartInfo::new(part_number, etag, length, checksum));
-                        });
                     }
                 }
             }
@@ -725,6 +758,8 @@ pub struct ComposeObject {
     legal_hold: bool,
     #[builder(default)]
     sources: Vec<ComposeSource>,
+    #[builder(default, setter(into))]
+    checksum_algorithm: Option<ChecksumAlgorithm>,
 }
 
 /// Builder type for [`ComposeObject`] that is returned by [`MinioClient::compose_object`](crate::s3::client::MinioClient::compose_object).
@@ -744,6 +779,7 @@ pub type ComposeObjectBldr = ComposeObjectBuilder<(
     (),
     (),
     (Vec<ComposeSource>,),
+    (),
 )>;
 
 impl ComposeObject {
@@ -766,6 +802,7 @@ impl ComposeObject {
             .retention(self.retention)
             .legal_hold(self.legal_hold)
             .sources(self.sources)
+            .checksum_algorithm(self.checksum_algorithm)
             .build()
             .send()
             .await;

src/s3/builders/put_object.rs

@@ -23,12 +23,14 @@ use crate::s3::response::{
     AbortMultipartUploadResponse, CompleteMultipartUploadResponse, CreateMultipartUploadResponse,
     PutObjectContentResponse, PutObjectResponse, UploadPartResponse,
 };
-use crate::s3::response_traits::HasEtagFromHeaders;
+use crate::s3::response_traits::{HasChecksumHeaders, HasEtagFromHeaders};
 use crate::s3::segmented_bytes::SegmentedBytes;
 use crate::s3::sse::Sse;
 use crate::s3::types::{PartInfo, Retention, S3Api, S3Request, ToS3Request};
+use crate::s3::utils::{
+    ChecksumAlgorithm, check_object_name, check_sse, compute_checksum_sb, insert,
+};
 use crate::s3::utils::{check_bucket_name, md5sum_hash, to_iso8601utc, url_encode};
-use crate::s3::utils::{check_object_name, check_sse, insert};
 use bytes::{Bytes, BytesMut};
 use http::Method;
 use std::{collections::HashMap, sync::Arc};
@@ -65,6 +67,13 @@ pub struct CreateMultipartUpload {
     legal_hold: bool,
     #[builder(default, setter(into))]
     content_type: Option<String>,
+    /// Optional checksum algorithm to use for data integrity verification.
+    ///
+    /// When specified, the server will compute checksums for each uploaded part
+    /// using this algorithm. Supported algorithms: CRC32, CRC32C, SHA1, SHA256, CRC64NVME.
+    /// The checksum is included in response headers for verification.
+    #[builder(default, setter(into))]
+    checksum_algorithm: Option<ChecksumAlgorithm>,
 }
 
 /// Builder type for [`CreateMultipartUpload`] that is returned by [`MinioClient::create_multipart_upload`](crate::s3::client::MinioClient::create_multipart_upload).
@@ -83,6 +92,7 @@ pub type CreateMultipartUploadBldr = CreateMultipartUploadBuilder<(
     (),
     (),
     (),
+    (),
 )>;
 
 impl S3Api for CreateMultipartUpload {
@@ -94,7 +104,7 @@ impl ToS3Request for CreateMultipartUpload {
         check_bucket_name(&self.bucket, true)?;
         check_object_name(&self.object)?;
 
-        let headers: Multimap = into_headers_put_object(
+        let mut headers: Multimap = into_headers_put_object(
             self.extra_headers,
             self.user_metadata,
             self.sse,
@@ -104,6 +114,10 @@ impl ToS3Request for CreateMultipartUpload {
             self.content_type,
         )?;
 
+        if let Some(algorithm) = self.checksum_algorithm {
+            headers.add(X_AMZ_CHECKSUM_ALGORITHM, algorithm.as_str().to_string());
+        }
+
         Ok(S3Request::builder()
             .client(self.client)
             .method(Method::POST)
@@ -197,6 +211,14 @@ pub struct CompleteMultipartUpload {
     upload_id: String,
     #[builder(!default)] // force required
     parts: Vec<PartInfo>,
+    /// Optional checksum algorithm used during multipart upload.
+    ///
+    /// When specified and all parts were uploaded with the same checksum algorithm,
+    /// the server will compute a composite checksum (checksum-of-checksums) for the
+    /// entire object. This must match the algorithm used in CreateMultipartUpload
+    /// and all UploadPart operations. Supported algorithms: CRC32, CRC32C, SHA1, SHA256, CRC64NVME.
+    #[builder(default, setter(into))]
+    checksum_algorithm: Option<ChecksumAlgorithm>,
 }
 
 /// Builder type for [`CompleteMultipartUpload`] that is returned by [`MinioClient::complete_multipart_upload`](crate::s3::client::MinioClient::complete_multipart_upload).
@@ -211,6 +233,7 @@ pub type CompleteMultipartUploadBldr = CompleteMultipartUploadBuilder<(
     (String,),
     (String,),
     (Vec<PartInfo>,),
+    (),
 )>;
 
 impl S3Api for CompleteMultipartUpload {
@@ -235,14 +258,37 @@ impl ToS3Request for CompleteMultipartUpload {
         // Set the capacity of the byte-buffer based on the part count - attempting
         // to avoid extra allocations when building the XML payload.
         let bytes: Bytes = {
-            let mut data = BytesMut::with_capacity(100 * self.parts.len() + 100);
+            let mut data = BytesMut::with_capacity(200 * self.parts.len() + 100);
             data.extend_from_slice(b"<CompleteMultipartUpload>");
             for part in self.parts.iter() {
                 data.extend_from_slice(b"<Part><PartNumber>");
                 data.extend_from_slice(part.number.to_string().as_bytes());
                 data.extend_from_slice(b"</PartNumber><ETag>");
                 data.extend_from_slice(part.etag.as_bytes());
-                data.extend_from_slice(b"</ETag></Part>");
+                data.extend_from_slice(b"</ETag>");
+                if let Some((algorithm, ref value)) = part.checksum {
+                    let (open_tag, close_tag) = match algorithm {
+                        ChecksumAlgorithm::CRC32 => {
+                            (&b"<ChecksumCRC32>"[..], &b"</ChecksumCRC32>"[..])
+                        }
+                        ChecksumAlgorithm::CRC32C => {
+                            (&b"<ChecksumCRC32C>"[..], &b"</ChecksumCRC32C>"[..])
+                        }
+                        ChecksumAlgorithm::SHA1 => {
+                            (&b"<ChecksumSHA1>"[..], &b"</ChecksumSHA1>"[..])
+                        }
+                        ChecksumAlgorithm::SHA256 => {
+                            (&b"<ChecksumSHA256>"[..], &b"</ChecksumSHA256>"[..])
+                        }
+                        ChecksumAlgorithm::CRC64NVME => {
+                            (&b"<ChecksumCRC64NVME>"[..], &b"</ChecksumCRC64NVME>"[..])
+                        }
+                    };
+                    data.extend_from_slice(open_tag);
+                    data.extend_from_slice(value.as_bytes());
+                    data.extend_from_slice(close_tag);
+                }
+                data.extend_from_slice(b"</Part>");
             }
             data.extend_from_slice(b"</CompleteMultipartUpload>");
             data.freeze()
@@ -252,6 +298,10 @@ impl ToS3Request for CompleteMultipartUpload {
         {
             headers.add(CONTENT_TYPE, "application/xml");
             headers.add(CONTENT_MD5, md5sum_hash(bytes.as_ref()));
+
+            if let Some(algorithm) = self.checksum_algorithm {
+                headers.add(X_AMZ_CHECKSUM_ALGORITHM, algorithm.as_str().to_string());
+            }
         }
         let mut query_params: Multimap = self.extra_query_params.unwrap_or_default();
         query_params.add("uploadId", self.upload_id);
@@ -311,6 +361,35 @@ pub struct UploadPart {
     upload_id: Option<String>,
     #[builder(default, setter(into))] // force required
     part_number: Option<u16>,
+
+    /// Optional checksum algorithm to use for this part's data integrity verification.
+    ///
+    /// When specified, computes a checksum of the part data using the selected algorithm
+    /// (CRC32, CRC32C, SHA1, SHA256, or CRC64NVME). The checksum is sent with the upload
+    /// and verified by the server. For multipart uploads, use the same algorithm for all parts.
+    #[builder(default, setter(into))]
+    checksum_algorithm: Option<ChecksumAlgorithm>,
+
+    /// When true and `checksum_algorithm` is set, uses trailing checksums.
+    ///
+    /// Trailing checksums use aws-chunked encoding where the checksum is computed
+    /// incrementally while streaming and appended at the end of the request body.
+    /// This avoids buffering the entire content to compute the checksum upfront.
+    ///
+    /// Defaults to false for backwards compatibility.
+    #[builder(default = false)]
+    use_trailing_checksum: bool,
+
+    /// When true, signs each chunk with AWS Signature V4 for streaming uploads.
+    ///
+    /// Requires `use_trailing_checksum` to be true and `checksum_algorithm` to be set.
+    /// Uses STREAMING-AWS4-HMAC-SHA256-PAYLOAD-TRAILER where each chunk is signed
+    /// and the trailer includes a trailer signature. This provides additional
+    /// integrity verification at the protocol level.
+    ///
+    /// Defaults to false for backwards compatibility.
+    #[builder(default = false)]
+    use_signed_streaming: bool,
 }
 
 /// Builder type for [`UploadPart`] that is returned by [`MinioClient::upload_part`](crate::s3::client::MinioClient::upload_part).
@@ -332,6 +411,9 @@ pub type UploadPartBldr = UploadPartBuilder<(
     (),
     (Option<String>,),
     (Option<u16>,),
+    (),
+    (),
+    (),
 )>;
 
 impl S3Api for UploadPart {
@@ -360,7 +442,7 @@ impl ToS3Request for UploadPart {
             }
         }
 
-        let headers: Multimap = into_headers_put_object(
+        let mut headers: Multimap = into_headers_put_object(
             self.extra_headers,
             self.user_metadata,
             self.sse,
@@ -370,6 +452,31 @@ impl ToS3Request for UploadPart {
             self.content_type,
         )?;
 
+        // Determine if we're using trailing checksums
+        let trailing_checksum = if self.use_trailing_checksum && self.checksum_algorithm.is_some() {
+            self.checksum_algorithm
+        } else {
+            None
+        };
+
+        // For upfront checksums (not trailing), compute and add to headers
+        if let Some(algorithm) = self.checksum_algorithm
+            && !self.use_trailing_checksum
+        {
+            let checksum_value = compute_checksum_sb(algorithm, &self.data);
+            headers.add(X_AMZ_CHECKSUM_ALGORITHM, algorithm.as_str().to_string());
+
+            match algorithm {
+                ChecksumAlgorithm::CRC32 => headers.add(X_AMZ_CHECKSUM_CRC32, checksum_value),
+                ChecksumAlgorithm::CRC32C => headers.add(X_AMZ_CHECKSUM_CRC32C, checksum_value),
+                ChecksumAlgorithm::SHA1 => headers.add(X_AMZ_CHECKSUM_SHA1, checksum_value),
+                ChecksumAlgorithm::SHA256 => headers.add(X_AMZ_CHECKSUM_SHA256, checksum_value),
+                ChecksumAlgorithm::CRC64NVME => {
+                    headers.add(X_AMZ_CHECKSUM_CRC64NVME, checksum_value)
+                }
+            }
+        }
+
         let mut query_params: Multimap = self.extra_query_params.unwrap_or_default();
 
         if let Some(upload_id) = self.upload_id {
@@ -388,6 +495,8 @@ impl ToS3Request for UploadPart {
             .object(self.object)
             .headers(headers)
             .body(self.data)
+            .trailing_checksum(trailing_checksum)
+            .use_signed_streaming(self.use_signed_streaming)
             .build())
     }
 }
@@ -454,6 +563,29 @@ pub struct PutObjectContent {
     part_size: Size,
     #[builder(default, setter(into))]
     content_type: Option<String>,
+    #[builder(default, setter(into))]
+    checksum_algorithm: Option<ChecksumAlgorithm>,
+
+    /// When true and `checksum_algorithm` is set, uses trailing checksums.
+    ///
+    /// Trailing checksums use aws-chunked encoding where the checksum is computed
+    /// incrementally while streaming and appended at the end of the request body.
+    /// This avoids buffering the entire content to compute the checksum upfront.
+    ///
+    /// Defaults to false for backwards compatibility.
+    #[builder(default = false)]
+    use_trailing_checksum: bool,
+
+    /// When true, signs each chunk with AWS Signature V4 for streaming uploads.
+    ///
+    /// Requires `use_trailing_checksum` to be true and `checksum_algorithm` to be set.
+    /// Uses STREAMING-AWS4-HMAC-SHA256-PAYLOAD-TRAILER where each chunk is signed
+    /// and the trailer includes a trailer signature. This provides additional
+    /// integrity verification at the protocol level.
+    ///
+    /// Defaults to false for backwards compatibility.
+    #[builder(default = false)]
+    use_signed_streaming: bool,
 
     // source data
     #[builder(!default, setter(into))] // force required + accept Into<String>
@@ -484,6 +616,9 @@ pub type PutObjectContentBldr = PutObjectContentBuilder<(
     (),
     (),
     (),
+    (),
+    (),
+    (),
     (ObjectContent,),
 )>;
 
@@ -542,6 +677,9 @@ impl PutObjectContent {
                     upload_id: None,
                     data: Arc::new(seg_bytes),
                     content_type: self.content_type.clone(),
+                    checksum_algorithm: self.checksum_algorithm,
+                    use_trailing_checksum: self.use_trailing_checksum,
+                    use_signed_streaming: self.use_signed_streaming,
                 })
                 .build()
                 .send()
@@ -572,6 +710,7 @@ impl PutObjectContent {
                 .retention(self.retention.clone())
                 .legal_hold(self.legal_hold)
                 .content_type(self.content_type.clone())
+                .checksum_algorithm(self.checksum_algorithm)
                 .build()
                 .send()
                 .await?;
@@ -667,15 +806,22 @@ impl PutObjectContent {
                 upload_id: Some(upload_id.to_string()),
                 data: Arc::new(part_content),
                 content_type: self.content_type.clone(),
+                checksum_algorithm: self.checksum_algorithm,
+                use_trailing_checksum: self.use_trailing_checksum,
+                use_signed_streaming: self.use_signed_streaming,
             }
             .send()
             .await?;
 
-            parts.push(PartInfo {
+            let checksum = self
-                number: part_number,
+                .checksum_algorithm
-                etag: resp.etag()?,
+                .and_then(|alg| resp.get_checksum(alg).map(|v| (alg, v)));
-                size: buffer_size,
+            parts.push(PartInfo::new(
-            });
+                part_number,
+                resp.etag()?,
+                buffer_size,
+                checksum,
+            ));
 
             // Finally, check if we are done.
             if buffer_size < part_size {
@@ -705,6 +851,7 @@ impl PutObjectContent {
             region: self.region,
             parts,
             upload_id,
+            checksum_algorithm: self.checksum_algorithm,
         }
         .send()
         .await?;

src/s3/client/mod.rs

@@ -57,8 +57,10 @@ use crate::s3::multimap_ext::{Multimap, MultimapExt};
 use crate::s3::response::*;
 use crate::s3::response_traits::{HasEtagFromHeaders, HasS3Fields};
 use crate::s3::segmented_bytes::SegmentedBytes;
-use crate::s3::signer::{SigningKeyCache, sign_v4_s3};
+use crate::s3::signer::{SigningKeyCache, sign_v4_s3, sign_v4_s3_with_context};
-use crate::s3::utils::{EMPTY_SHA256, check_ssec_with_log, sha256_hash_sb, to_amz_date, utc_now};
+use crate::s3::utils::{
+    ChecksumAlgorithm, EMPTY_SHA256, check_ssec_with_log, sha256_hash_sb, to_amz_date, utc_now,
+};
 
 mod append_object;
 mod bucket_exists;
@@ -663,8 +665,14 @@ impl MinioClient {
         bucket_name: Option<&str>,
         object_name: Option<&str>,
         body: Option<Arc<SegmentedBytes>>,
+        trailing_checksum: Option<ChecksumAlgorithm>,
+        use_signed_streaming: bool,
         retry: bool,
     ) -> Result<reqwest::Response, Error> {
+        use crate::s3::aws_chunked::{
+            AwsChunkedEncoder, RechunkingStream, SignedAwsChunkedEncoder,
+        };
+
         let mut url = self.shared.base_url.build_url(
             method,
             region,
@@ -675,14 +683,55 @@ impl MinioClient {
         let mut extensions = http::Extensions::default();
 
         headers.add(HOST, url.host_header_value());
+
+        // Determine if we're using trailing checksums (signed or unsigned)
+        let use_trailing = trailing_checksum.is_some()
+            && matches!(*method, Method::PUT | Method::POST)
+            && body.is_some();
+        let use_signed_trailing = use_trailing && use_signed_streaming;
+
         let sha256: String = match *method {
             Method::PUT | Method::POST => {
                 if !headers.contains_key(CONTENT_TYPE) {
                     // Empty body with Content-Type can cause some MinIO versions to expect XML
                     headers.add(CONTENT_TYPE, "application/octet-stream");
                 }
-                let len: usize = body.as_ref().map_or(0, |b| b.len());
+                let raw_len: usize = body.as_ref().map_or(0, |b| b.len());
-                headers.add(CONTENT_LENGTH, len.to_string());
+
+                if use_trailing {
+                    // For trailing checksums, use aws-chunked encoding
+                    let algorithm = trailing_checksum.unwrap();
+
+                    // Set headers for aws-chunked encoding
+                    headers.add(CONTENT_ENCODING, "aws-chunked");
+                    headers.add(X_AMZ_DECODED_CONTENT_LENGTH, raw_len.to_string());
+                    headers.add(X_AMZ_TRAILER, algorithm.header_name());
+
+                    // Calculate the encoded length for Content-Length
+                    let encoded_len = if use_signed_trailing {
+                        crate::s3::aws_chunked::calculate_signed_encoded_length(
+                            raw_len as u64,
+                            crate::s3::aws_chunked::default_chunk_size(),
+                            algorithm,
+                        )
+                    } else {
+                        crate::s3::aws_chunked::calculate_encoded_length(
+                            raw_len as u64,
+                            crate::s3::aws_chunked::default_chunk_size(),
+                            algorithm,
+                        )
+                    };
+                    headers.add(CONTENT_LENGTH, encoded_len.to_string());
+
+                    // Use appropriate Content-SHA256 value
+                    if use_signed_trailing {
+                        STREAMING_AWS4_HMAC_SHA256_PAYLOAD_TRAILER.into()
+                    } else {
+                        STREAMING_UNSIGNED_PAYLOAD_TRAILER.into()
+                    }
+                } else {
+                    // Standard upfront checksum
+                    headers.add(CONTENT_LENGTH, raw_len.to_string());
                     match body {
                         None => EMPTY_SHA256.into(),
                         Some(ref v) => {
@@ -691,6 +740,7 @@ impl MinioClient {
                         }
                     }
                 }
+            }
             _ => EMPTY_SHA256.into(),
         };
         headers.add(X_AMZ_CONTENT_SHA256, sha256.clone());
@@ -723,11 +773,29 @@ impl MinioClient {
             headers.add("x-minio-redirect-to", url.to_string());
         }
 
-        if let Some(p) = &self.shared.provider {
+        // For signed streaming, we need the signing context for chunk signatures
+        let chunk_signing_context = if let Some(p) = &self.shared.provider {
             let creds = p.fetch();
             if creds.session_token.is_some() {
                 headers.add(X_AMZ_SECURITY_TOKEN, creds.session_token.unwrap());
             }
+
+            if use_signed_trailing {
+                // Use the version that returns chunk signing context
+                Some(sign_v4_s3_with_context(
+                    &self.shared.signing_key_cache,
+                    method,
+                    &url.path,
+                    region,
+                    headers,
+                    query_params,
+                    &creds.access_key,
+                    &creds.secret_key,
+                    &sha256,
+                    date,
+                ))
+            } else {
+                // Standard signing without context
                 sign_v4_s3(
                     &self.shared.signing_key_cache,
                     method,
@@ -740,7 +808,11 @@ impl MinioClient {
                     &sha256,
                     date,
                 );
+                None
             }
+        } else {
+            None
+        };
 
         let mut req = self.http_client.request(method.clone(), url.to_string());
 
@@ -766,8 +838,28 @@ impl MinioClient {
                 None => BodyIterator::Empty(std::iter::empty()),
             };
             let stream = futures_util::stream::iter(iter.map(|b| -> Result<_, Error> { Ok(b) }));
+
+            if use_signed_trailing {
+                // Wrap stream with signed aws-chunked encoder for trailing checksum.
+                // Re-chunk the stream to match the chunk size used in Content-Length calculation,
+                // ensuring the actual encoded bytes match the declared Content-Length.
+                let algorithm = trailing_checksum.unwrap();
+                let context =
+                    chunk_signing_context.expect("signing context required for signed streaming");
+                let rechunked = RechunkingStream::with_default_chunk_size(stream);
+                let encoder = SignedAwsChunkedEncoder::new(rechunked, algorithm, context);
+                req = req.body(Body::wrap_stream(encoder));
+            } else if use_trailing {
+                // Wrap stream with unsigned aws-chunked encoder for trailing checksum.
+                // Re-chunk the stream to match the chunk size used in Content-Length calculation.
+                let algorithm = trailing_checksum.unwrap();
+                let rechunked = RechunkingStream::with_default_chunk_size(stream);
+                let encoder = AwsChunkedEncoder::new(rechunked, algorithm);
+                req = req.body(Body::wrap_stream(encoder));
+            } else {
                 req = req.body(Body::wrap_stream(stream));
             }
+        }
 
         let resp = req.send().await;
 
@@ -825,6 +917,8 @@ impl MinioClient {
         bucket_name: &Option<&str>,
         object_name: &Option<&str>,
         data: Option<Arc<SegmentedBytes>>,
+        trailing_checksum: Option<ChecksumAlgorithm>,
+        use_signed_streaming: bool,
     ) -> Result<reqwest::Response, Error> {
         let resp: Result<reqwest::Response, Error> = self
             .execute_internal(
@@ -835,6 +929,8 @@ impl MinioClient {
                 bucket_name.as_deref(),
                 object_name.as_deref(),
                 data.as_ref().map(Arc::clone),
+                trailing_checksum,
+                use_signed_streaming,
                 true,
             )
             .await;
@@ -859,6 +955,8 @@ impl MinioClient {
             bucket_name.as_deref(),
             object_name.as_deref(),
             data,
+            trailing_checksum,
+            use_signed_streaming,
             false,
         )
         .await

src/s3/error.rs

@@ -148,6 +148,9 @@ pub enum ValidationErr {
         got: u32,
     },
 
+    #[error("Checksum mismatch; expected: {expected}, computed: {computed}")]
+    ChecksumMismatch { expected: String, computed: String },
+
     #[error("Unknown event type: {0}")]
     UnknownEventType(String),
 

src/s3/mod.rs

@@ -15,6 +15,7 @@
 
 //! Implementation of Simple Storage Service (aka S3) client
 
+pub mod aws_chunked;
 pub mod builders;
 pub mod client;
 pub mod creds;

src/s3/response/append_object.rs

@@ -14,7 +14,8 @@
 // limitations under the License.
 
 use crate::s3::response_traits::{
-    HasBucket, HasEtagFromHeaders, HasObject, HasObjectSize, HasRegion, HasVersion,
+    HasBucket, HasChecksumHeaders, HasEtagFromHeaders, HasObject, HasObjectSize, HasRegion,
+    HasVersion,
 };
 use crate::s3::types::S3Request;
 use crate::{impl_from_s3response, impl_has_s3fields};
@@ -40,3 +41,4 @@ impl HasRegion for AppendObjectResponse {}
 impl HasVersion for AppendObjectResponse {}
 impl HasEtagFromHeaders for AppendObjectResponse {}
 impl HasObjectSize for AppendObjectResponse {}
+impl HasChecksumHeaders for AppendObjectResponse {}

src/s3/response/copy_object.rs

@@ -13,7 +13,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use crate::s3::response_traits::{HasBucket, HasEtagFromBody, HasObject, HasRegion, HasVersion};
+use crate::s3::response_traits::{
+    HasBucket, HasChecksumHeaders, HasEtagFromBody, HasObject, HasRegion, HasVersion,
+};
 use crate::s3::types::S3Request;
 use crate::{impl_from_s3response, impl_has_s3fields};
 use bytes::Bytes;
@@ -35,6 +37,7 @@ impl HasObject for S3Response2 {}
 impl HasRegion for S3Response2 {}
 impl HasVersion for S3Response2 {}
 impl HasEtagFromBody for S3Response2 {}
+impl HasChecksumHeaders for S3Response2 {}
 
 /// Represents the response of the `upload_part_copy` API call.
 /// This struct contains metadata and information about the part being copied during a multipart upload.

src/s3/response/get_object.rs

@@ -16,12 +16,22 @@
 use crate::impl_has_s3fields;
 use crate::s3::builders::ObjectContent;
 use crate::s3::error::{Error, ValidationErr};
-use crate::s3::response_traits::{HasBucket, HasEtagFromHeaders, HasObject, HasRegion, HasVersion};
+use crate::s3::response_traits::{
+    HasBucket, HasChecksumHeaders, HasEtagFromHeaders, HasObject, HasRegion, HasVersion,
+};
 use crate::s3::types::{FromS3Response, S3Request};
+use crate::s3::utils::{ChecksumAlgorithm, b64_encode, compute_checksum};
 use async_trait::async_trait;
 use bytes::Bytes;
-use futures_util::TryStreamExt;
+use crc_fast::{CrcAlgorithm, Digest as CrcFastDigest};
+use futures_util::{Stream, TryStreamExt};
 use http::HeaderMap;
+#[cfg(feature = "ring")]
+use ring::digest::{Context, SHA256};
+use sha1::{Digest as Sha1Digest, Sha1};
+#[cfg(not(feature = "ring"))]
+use sha2::Sha256;
+use std::io;
 use std::mem;
 use std::pin::Pin;
 
@@ -30,12 +40,174 @@ pub type BoxedByteStream = (
     Pin<Box<dyn futures_util::Stream<Item = std::io::Result<Bytes>> + Send>>,
     u64,
 );
+use std::task::{Context as TaskContext, Poll};
+
+/// Stateful checksum hasher for streaming verification.
+///
+/// This enum provides incremental checksum computation across multiple data chunks,
+/// enabling efficient verification of large objects without loading them entirely into memory.
+/// Each variant wraps the appropriate hasher implementation for its algorithm.
+///
+/// The hasher is used internally by [`GetObjectResponse::content()`] to verify checksums
+/// transparently during streaming, with minimal performance overhead.
+enum ChecksumHasher {
+    Crc32(CrcFastDigest),
+    Crc32c(CrcFastDigest),
+    Crc64nvme(CrcFastDigest),
+    Sha1(Sha1),
+    #[cfg(feature = "ring")]
+    Sha256(Context),
+    #[cfg(not(feature = "ring"))]
+    Sha256(Sha256),
+}
+
+impl ChecksumHasher {
+    /// Creates a new checksum hasher for the specified algorithm.
+    ///
+    /// Initializes the appropriate hasher implementation with cached instances
+    /// for CRC variants to optimize performance.
+    ///
+    /// # Arguments
+    ///
+    /// * `algorithm` - The checksum algorithm to use for verification
+    fn new(algorithm: ChecksumAlgorithm) -> Self {
+        match algorithm {
+            ChecksumAlgorithm::CRC32 => {
+                ChecksumHasher::Crc32(CrcFastDigest::new(CrcAlgorithm::Crc32IsoHdlc))
+            }
+            ChecksumAlgorithm::CRC32C => {
+                ChecksumHasher::Crc32c(CrcFastDigest::new(CrcAlgorithm::Crc32Iscsi))
+            }
+            ChecksumAlgorithm::CRC64NVME => {
+                ChecksumHasher::Crc64nvme(CrcFastDigest::new(CrcAlgorithm::Crc64Nvme))
+            }
+            ChecksumAlgorithm::SHA1 => ChecksumHasher::Sha1(Sha1::new()),
+            #[cfg(feature = "ring")]
+            ChecksumAlgorithm::SHA256 => ChecksumHasher::Sha256(Context::new(&SHA256)),
+            #[cfg(not(feature = "ring"))]
+            ChecksumAlgorithm::SHA256 => ChecksumHasher::Sha256(Sha256::new()),
+        }
+    }
+
+    /// Updates the checksum computation with a new chunk of data.
+    ///
+    /// This method is called incrementally as data streams through, allowing
+    /// verification without buffering the entire object in memory.
+    ///
+    /// # Arguments
+    ///
+    /// * `data` - The next chunk of data to include in the checksum
+    fn update(&mut self, data: &[u8]) {
+        match self {
+            ChecksumHasher::Crc32(digest) => digest.update(data),
+            ChecksumHasher::Crc32c(digest) => digest.update(data),
+            ChecksumHasher::Crc64nvme(digest) => digest.update(data),
+            ChecksumHasher::Sha1(hasher) => hasher.update(data),
+            #[cfg(feature = "ring")]
+            ChecksumHasher::Sha256(ctx) => ctx.update(data),
+            #[cfg(not(feature = "ring"))]
+            ChecksumHasher::Sha256(hasher) => hasher.update(data),
+        }
+    }
+
+    /// Completes the checksum computation and returns the base64-encoded result.
+    ///
+    /// This consumes the hasher and produces the final checksum value in the format
+    /// expected by S3 headers (base64-encoded). The result can be compared directly
+    /// with the checksum value from response headers.
+    ///
+    /// # Returns
+    ///
+    /// Base64-encoded checksum string matching the S3 header format.
+    fn finalize(self) -> String {
+        match self {
+            // crc-fast returns u64 for all algorithms; CRC32 variants need cast to u32
+            ChecksumHasher::Crc32(digest) => b64_encode((digest.finalize() as u32).to_be_bytes()),
+            ChecksumHasher::Crc32c(digest) => b64_encode((digest.finalize() as u32).to_be_bytes()),
+            ChecksumHasher::Crc64nvme(digest) => b64_encode(digest.finalize().to_be_bytes()),
+            ChecksumHasher::Sha1(hasher) => {
+                let result = hasher.finalize();
+                b64_encode(&result[..])
+            }
+            #[cfg(feature = "ring")]
+            ChecksumHasher::Sha256(ctx) => b64_encode(ctx.finish().as_ref()),
+            #[cfg(not(feature = "ring"))]
+            ChecksumHasher::Sha256(hasher) => {
+                let result = hasher.finalize();
+                b64_encode(&result[..])
+            }
+        }
+    }
+}
+
+/// A stream wrapper that computes checksum incrementally while streaming data
+struct ChecksumVerifyingStream<S> {
+    inner: S,
+    hasher: Option<ChecksumHasher>,
+    expected_checksum: String,
+    finished: bool,
+}
+
+impl<S> ChecksumVerifyingStream<S>
+where
+    S: Stream<Item = Result<Bytes, reqwest::Error>> + Unpin,
+{
+    fn new(stream: S, algorithm: ChecksumAlgorithm, expected_checksum: String) -> Self {
+        Self {
+            inner: stream,
+            hasher: Some(ChecksumHasher::new(algorithm)),
+            expected_checksum,
+            finished: false,
+        }
+    }
+}
+
+impl<S> Stream for ChecksumVerifyingStream<S>
+where
+    S: Stream<Item = Result<Bytes, reqwest::Error>> + Unpin,
+{
+    type Item = io::Result<Bytes>;
+
+    fn poll_next(mut self: Pin<&mut Self>, cx: &mut TaskContext<'_>) -> Poll<Option<Self::Item>> {
+        if self.finished {
+            return Poll::Ready(None);
+        }
+
+        match Pin::new(&mut self.inner).poll_next(cx) {
+            Poll::Ready(Some(Ok(bytes))) => {
+                if let Some(hasher) = &mut self.hasher {
+                    hasher.update(&bytes);
+                }
+                Poll::Ready(Some(Ok(bytes)))
+            }
+            Poll::Ready(Some(Err(e))) => {
+                self.finished = true;
+                Poll::Ready(Some(Err(io::Error::other(e))))
+            }
+            Poll::Ready(None) => {
+                self.finished = true;
+                if let Some(hasher) = self.hasher.take() {
+                    let computed = hasher.finalize();
+                    if computed != self.expected_checksum {
+                        return Poll::Ready(Some(Err(io::Error::other(format!(
+                            "Checksum mismatch: expected {}, computed {}",
+                            self.expected_checksum, computed
+                        )))));
+                    }
+                }
+                Poll::Ready(None)
+            }
+            Poll::Pending => Poll::Pending,
+        }
+    }
+}
 
 pub struct GetObjectResponse {
     request: S3Request,
     headers: HeaderMap,
     body: Bytes, // Note: not used
     resp: reqwest::Response,
+    verify_checksum: bool,
 }
 
 impl_has_s3fields!(GetObjectResponse);
@@ -45,11 +217,62 @@ impl HasRegion for GetObjectResponse {}
 impl HasObject for GetObjectResponse {}
 impl HasVersion for GetObjectResponse {}
 impl HasEtagFromHeaders for GetObjectResponse {}
+impl HasChecksumHeaders for GetObjectResponse {}
 
 impl GetObjectResponse {
+    /// Checks if the checksum is a composite (multipart) checksum.
+    ///
+    /// Composite checksums are returned for objects uploaded via multipart upload.
+    /// They represent a checksum-of-checksums and cannot be verified by computing
+    /// a checksum over the full object data.
+    ///
+    /// Detection is based solely on the `x-amz-checksum-type: COMPOSITE` header.
+    /// We intentionally do NOT try to detect composite checksums by parsing the
+    /// checksum value for a `-N` suffix, as this could cause false positives if
+    /// the server uses base64url encoding (which includes `-` in its alphabet).
+    fn is_composite_checksum(&self) -> bool {
+        if let Some(checksum_type) = self.checksum_type()
+            && checksum_type.eq_ignore_ascii_case("COMPOSITE")
+        {
+            return true;
+        }
+        false
+    }
+
     /// Returns the content of the object as a (streaming) byte buffer. Note: consumes the response.
+    ///
+    /// If `verify_checksum` is enabled and the server provided checksums, the stream will
+    /// automatically verify the checksum incrementally as data is read, maintaining streaming performance.
+    ///
+    /// **Note on multipart objects**: Objects uploaded via multipart upload have COMPOSITE checksums
+    /// (checksum-of-checksums) which cannot be verified by computing a checksum over the downloaded
+    /// data. For these objects, checksum verification is automatically skipped.
     pub fn content(self) -> Result<ObjectContent, Error> {
         let content_length: u64 = self.object_size()?;
+
+        // Skip verification for composite checksums (multipart uploads)
+        // Composite checksums are checksum-of-checksums and cannot be verified
+        // by computing a checksum over the full object data
+        if self.is_composite_checksum() {
+            log::debug!(
+                "Skipping checksum verification for composite checksum (multipart upload). \
+                 Composite checksums cannot be verified without part boundaries."
+            );
+            let body = self.resp.bytes_stream().map_err(std::io::Error::other);
+            return Ok(ObjectContent::new_from_stream(body, Some(content_length)));
+        }
+
+        if let (true, Some(algorithm)) = (self.verify_checksum, self.detect_checksum_algorithm())
+            && let Some(expected) = self.get_checksum(algorithm)
+        {
+            let stream = self.resp.bytes_stream();
+            let verifying_stream = ChecksumVerifyingStream::new(stream, algorithm, expected);
+            return Ok(ObjectContent::new_from_stream(
+                verifying_stream,
+                Some(content_length),
+            ));
+        }
+
         let body = self.resp.bytes_stream().map_err(std::io::Error::other);
         Ok(ObjectContent::new_from_stream(body, Some(content_length)))
     }
@@ -78,12 +301,68 @@ impl GetObjectResponse {
             .map_err(|e| ValidationErr::HttpError(e).into())
     }
 
+    /// Sets whether to automatically verify checksums when calling `content()`.
+    /// Default is `true`. Verification is performed incrementally during streaming with minimal overhead.
+    /// Set to `false` to disable checksum verification entirely.
+    pub fn with_verification(mut self, verify: bool) -> Self {
+        self.verify_checksum = verify;
+        self
+    }
+
     /// Returns the content size (in Bytes) of the object.
     pub fn object_size(&self) -> Result<u64, ValidationErr> {
         self.resp
             .content_length()
             .ok_or(ValidationErr::ContentLengthUnknown)
     }
+
+    /// Returns the content with automatic checksum verification.
+    ///
+    /// Downloads the full content, computes its checksum, and verifies against server checksum.
+    ///
+    /// **Note on multipart objects**: Objects uploaded via multipart upload have COMPOSITE checksums
+    /// (checksum-of-checksums) which cannot be verified by computing a checksum over the downloaded
+    /// data. For these objects, checksum verification is automatically skipped and the content is
+    /// returned without verification.
+    pub async fn content_verified(self) -> Result<Bytes, Error> {
+        // Skip verification for composite checksums (multipart uploads)
+        if self.is_composite_checksum() {
+            log::debug!(
+                "Skipping checksum verification for composite checksum (multipart upload). \
+                 Composite checksums cannot be verified without part boundaries."
+            );
+            return self
+                .resp
+                .bytes()
+                .await
+                .map_err(|e| ValidationErr::HttpError(e).into());
+        }
+
+        let algorithm = self.detect_checksum_algorithm();
+        let expected_checksum = algorithm.and_then(|algo| self.get_checksum(algo));
+
+        let bytes = self.resp.bytes().await.map_err(ValidationErr::HttpError)?;
+
+        if let (Some(algo), Some(expected)) = (algorithm, expected_checksum) {
+            let computed = compute_checksum(algo, &bytes);
+
+            if computed != expected {
+                return Err(Error::Validation(ValidationErr::ChecksumMismatch {
+                    expected,
+                    computed,
+                }));
+            }
+        }
+
+        Ok(bytes)
+    }
+
+    /// Returns whether the object has a composite checksum (from multipart upload).
+    ///
+    /// This can be used to check if checksum verification will be skipped.
+    pub fn has_composite_checksum(&self) -> bool {
+        self.is_composite_checksum()
+    }
 }
 
 #[async_trait]
@@ -98,6 +377,7 @@ impl FromS3Response for GetObjectResponse {
             headers: mem::take(resp.headers_mut()),
             body: Bytes::new(),
             resp,
+            verify_checksum: true, // Default to auto-verify
         })
     }
 }

src/s3/response/put_object.rs

@@ -14,7 +14,9 @@
 // limitations under the License.
 
 use crate::s3::error::ValidationErr;
-use crate::s3::response_traits::{HasBucket, HasEtagFromHeaders, HasObject, HasRegion, HasVersion};
+use crate::s3::response_traits::{
+    HasBucket, HasChecksumHeaders, HasEtagFromHeaders, HasObject, HasRegion, HasVersion,
+};
 use crate::s3::types::S3Request;
 use crate::s3::utils::get_text_result;
 use crate::{impl_from_s3response, impl_from_s3response_with_size, impl_has_s3fields};
@@ -40,6 +42,7 @@ impl HasObject for S3Response1 {}
 impl HasRegion for S3Response1 {}
 impl HasVersion for S3Response1 {}
 impl HasEtagFromHeaders for S3Response1 {}
+impl HasChecksumHeaders for S3Response1 {}
 
 /// Extended response struct for operations that need additional data like object size
 #[derive(Clone, Debug)]
@@ -60,6 +63,7 @@ impl HasObject for S3Response1WithSize {}
 impl HasRegion for S3Response1WithSize {}
 impl HasVersion for S3Response1WithSize {}
 impl HasEtagFromHeaders for S3Response1WithSize {}
+impl HasChecksumHeaders for S3Response1WithSize {}
 
 impl S3Response1WithSize {
     pub fn new(response: S3Response1, object_size: u64) -> Self {
@@ -93,6 +97,7 @@ impl HasObject for S3MultipartResponse {}
 impl HasRegion for S3MultipartResponse {}
 impl HasVersion for S3MultipartResponse {}
 impl HasEtagFromHeaders for S3MultipartResponse {}
+impl HasChecksumHeaders for S3MultipartResponse {}
 
 impl S3MultipartResponse {
     /// Returns the upload ID for the multipart upload, while consuming the response.

src/s3/response/stat_object.rs

@@ -16,8 +16,8 @@
 use crate::s3::error::ValidationErr;
 use crate::s3::header_constants::*;
 use crate::s3::response_traits::{
-    HasBucket, HasEtagFromHeaders, HasIsDeleteMarker, HasObject, HasObjectSize, HasRegion,
+    HasBucket, HasChecksumHeaders, HasEtagFromHeaders, HasIsDeleteMarker, HasObject, HasObjectSize,
-    HasS3Fields, HasVersion,
+    HasRegion, HasS3Fields, HasVersion,
 };
 use crate::s3::types::S3Request;
 use crate::s3::types::{RetentionMode, parse_legal_hold};
@@ -46,6 +46,7 @@ impl HasRegion for StatObjectResponse {}
 impl HasObject for StatObjectResponse {}
 impl HasEtagFromHeaders for StatObjectResponse {}
 impl HasIsDeleteMarker for StatObjectResponse {}
+impl HasChecksumHeaders for StatObjectResponse {}
 impl HasVersion for StatObjectResponse {}
 impl HasObjectSize for StatObjectResponse {}
 

src/s3/response_traits.rs

@@ -67,7 +67,7 @@
 use crate::s3::error::ValidationErr;
 use crate::s3::header_constants::*;
 use crate::s3::types::S3Request;
-use crate::s3::utils::{get_text_result, parse_bool, trim_quotes};
+use crate::s3::utils::{ChecksumAlgorithm, get_text_result, parse_bool, trim_quotes};
 use bytes::{Buf, Bytes};
 use http::HeaderMap;
 use std::collections::HashMap;
@@ -275,3 +275,90 @@ pub trait HasTagging: HasS3Fields {
         Ok(tags)
     }
 }
+
+/// Provides checksum-related methods for S3 responses with headers.
+///
+/// This trait provides default implementations for extracting and detecting checksums
+/// from S3 response headers. Implement this trait for any response type that has
+/// `HeaderMap` access via `HasS3Fields`.
+pub trait HasChecksumHeaders: HasS3Fields {
+    /// Extracts the checksum value from response headers for the specified algorithm.
+    ///
+    /// Retrieves the base64-encoded checksum value from the appropriate S3 response header
+    /// (x-amz-checksum-crc32, x-amz-checksum-crc32c, x-amz-checksum-crc64nvme,
+    /// x-amz-checksum-sha1, or x-amz-checksum-sha256).
+    ///
+    /// # Arguments
+    ///
+    /// * `algorithm` - The checksum algorithm to retrieve
+    ///
+    /// # Returns
+    ///
+    /// - `Some(checksum)` if the header is present, containing the base64-encoded checksum value
+    /// - `None` if the header is not found
+    ///
+    /// # Use Cases
+    ///
+    /// - Compare with locally computed checksums for manual verification
+    /// - Store checksum values for audit or compliance records
+    /// - Verify integrity after downloading to disk
+    #[inline]
+    fn get_checksum(&self, algorithm: ChecksumAlgorithm) -> Option<String> {
+        let header_name = match algorithm {
+            ChecksumAlgorithm::CRC32 => X_AMZ_CHECKSUM_CRC32,
+            ChecksumAlgorithm::CRC32C => X_AMZ_CHECKSUM_CRC32C,
+            ChecksumAlgorithm::SHA1 => X_AMZ_CHECKSUM_SHA1,
+            ChecksumAlgorithm::SHA256 => X_AMZ_CHECKSUM_SHA256,
+            ChecksumAlgorithm::CRC64NVME => X_AMZ_CHECKSUM_CRC64NVME,
+        };
+
+        self.headers()
+            .get(header_name)
+            .and_then(|v| v.to_str().ok())
+            .map(|s| s.to_string())
+    }
+
+    /// Returns the checksum type from response headers.
+    ///
+    /// The checksum type indicates whether the checksum represents:
+    /// - `FULL_OBJECT` - A checksum computed over the entire object
+    /// - `COMPOSITE` - A checksum-of-checksums for multipart uploads
+    ///
+    /// # Returns
+    ///
+    /// - `Some(type_string)` if the `x-amz-checksum-type` header is present
+    /// - `None` if the header is not found
+    #[inline]
+    fn checksum_type(&self) -> Option<String> {
+        self.headers()
+            .get(X_AMZ_CHECKSUM_TYPE)
+            .and_then(|v| v.to_str().ok())
+            .map(|s| s.to_string())
+    }
+
+    /// Detects which checksum algorithm was used by the server (if any).
+    ///
+    /// Examines response headers to determine if the server computed a checksum
+    /// for this operation.
+    ///
+    /// # Returns
+    ///
+    /// - `Some(algorithm)` if a checksum header is found (CRC32, CRC32C, CRC64NVME, SHA1, or SHA256)
+    /// - `None` if no checksum headers are present
+    #[inline]
+    fn detect_checksum_algorithm(&self) -> Option<ChecksumAlgorithm> {
+        if self.headers().contains_key(X_AMZ_CHECKSUM_CRC32) {
+            Some(ChecksumAlgorithm::CRC32)
+        } else if self.headers().contains_key(X_AMZ_CHECKSUM_CRC32C) {
+            Some(ChecksumAlgorithm::CRC32C)
+        } else if self.headers().contains_key(X_AMZ_CHECKSUM_CRC64NVME) {
+            Some(ChecksumAlgorithm::CRC64NVME)
+        } else if self.headers().contains_key(X_AMZ_CHECKSUM_SHA1) {
+            Some(ChecksumAlgorithm::SHA1)
+        } else if self.headers().contains_key(X_AMZ_CHECKSUM_SHA256) {
+            Some(ChecksumAlgorithm::SHA256)
+        } else {
+            None
+        }
+    }
+}

src/s3/signer.rs

@@ -394,6 +394,155 @@ pub(crate) fn post_presign_v4(
     get_signature(&signing_key, string_to_sign.as_bytes())
 }
 
+// ===========================
+// Chunk Signing for STREAMING-AWS4-HMAC-SHA256-PAYLOAD-TRAILER
+// ===========================
+
+/// Context required for signing streaming chunks.
+///
+/// This struct captures the parameters needed to sign each chunk
+/// in STREAMING-AWS4-HMAC-SHA256-PAYLOAD-TRAILER uploads.
+/// The signing key can be reused for all chunks since it only depends
+/// on date/region/service which don't change within a request.
+#[derive(Debug, Clone)]
+pub struct ChunkSigningContext {
+    /// The signing key (Arc for zero-copy sharing across chunks)
+    pub signing_key: Arc<[u8]>,
+    /// AMZ date format: 20241219T120000Z
+    pub date_time: String,
+    /// Credential scope: 20241219/us-east-1/s3/aws4_request
+    pub scope: String,
+    /// The seed signature from Authorization header (hex-encoded)
+    pub seed_signature: String,
+}
+
+/// Signs a single chunk for STREAMING-AWS4-HMAC-SHA256-PAYLOAD streaming.
+///
+/// The string-to-sign format is:
+/// ```text
+/// AWS4-HMAC-SHA256-PAYLOAD
+/// <timestamp>
+/// <scope>
+/// <previous-signature>
+/// <SHA256-of-empty-string>
+/// <SHA256-of-chunk-data>
+/// ```
+///
+/// # Arguments
+/// * `signing_key` - The derived signing key
+/// * `date_time` - AMZ date format (e.g., "20130524T000000Z")
+/// * `scope` - Credential scope (e.g., "20130524/us-east-1/s3/aws4_request")
+/// * `previous_signature` - Previous chunk's signature (or seed signature for first chunk)
+/// * `chunk_hash` - Pre-computed SHA256 hash of the chunk data (hex-encoded)
+///
+/// # Returns
+/// The hex-encoded signature for this chunk.
+pub fn sign_chunk(
+    signing_key: &[u8],
+    date_time: &str,
+    scope: &str,
+    previous_signature: &str,
+    chunk_hash: &str,
+) -> String {
+    // SHA256 of empty string (constant per AWS spec)
+    const EMPTY_SHA256: &str = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855";
+
+    // Build string-to-sign per AWS spec
+    let string_to_sign = format!(
+        "AWS4-HMAC-SHA256-PAYLOAD\n{}\n{}\n{}\n{}\n{}",
+        date_time, scope, previous_signature, EMPTY_SHA256, chunk_hash
+    );
+
+    hmac_hash_hex(signing_key, string_to_sign.as_bytes())
+}
+
+/// Signs the trailer for STREAMING-AWS4-HMAC-SHA256-PAYLOAD-TRAILER.
+///
+/// The string-to-sign format is:
+/// ```text
+/// AWS4-HMAC-SHA256-TRAILER
+/// <timestamp>
+/// <scope>
+/// <last-chunk-signature>
+/// <SHA256-of-canonical-trailers>
+/// ```
+///
+/// # Arguments
+/// * `signing_key` - The derived signing key
+/// * `date_time` - AMZ date format (e.g., "20130524T000000Z")
+/// * `scope` - Credential scope (e.g., "20130524/us-east-1/s3/aws4_request")
+/// * `last_chunk_signature` - The signature of the final 0-byte chunk
+/// * `canonical_trailers_hash` - Pre-computed SHA256 hash of canonical trailers (hex-encoded)
+///
+/// The canonical trailers format is: `<lowercase-header-name>:<trimmed-value>\n`
+/// Example: `x-amz-checksum-crc32c:sOO8/Q==\n`
+///
+/// **Note**: The canonical form uses LF (`\n`), not CRLF (`\r\n`), even though
+/// the HTTP wire format uses CRLF. This is per AWS SigV4 specification.
+///
+/// # Returns
+/// The hex-encoded trailer signature.
+pub fn sign_trailer(
+    signing_key: &[u8],
+    date_time: &str,
+    scope: &str,
+    last_chunk_signature: &str,
+    canonical_trailers_hash: &str,
+) -> String {
+    // Build string-to-sign per AWS spec
+    let string_to_sign = format!(
+        "AWS4-HMAC-SHA256-TRAILER\n{}\n{}\n{}\n{}",
+        date_time, scope, last_chunk_signature, canonical_trailers_hash
+    );
+
+    hmac_hash_hex(signing_key, string_to_sign.as_bytes())
+}
+
+/// Signs request and returns context for chunk signing.
+///
+/// This is used for STREAMING-AWS4-HMAC-SHA256-PAYLOAD-TRAILER uploads
+/// where the encoder needs the signing key and seed signature to sign
+/// each chunk during streaming.
+///
+/// The `cache` parameter should be the per-client `signing_key_cache` from `SharedClientItems`.
+pub(crate) fn sign_v4_s3_with_context(
+    cache: &RwLock<SigningKeyCache>,
+    method: &Method,
+    uri: &str,
+    region: &str,
+    headers: &mut Multimap,
+    query_params: &Multimap,
+    access_key: &str,
+    secret_key: &str,
+    content_sha256: &str,
+    date: UtcTime,
+) -> ChunkSigningContext {
+    let scope = get_scope(date, region, "s3");
+    let (signed_headers, canonical_headers) = headers.get_canonical_headers();
+    let canonical_query_string = query_params.get_canonical_query_string();
+    let canonical_request_hash = get_canonical_request_hash(
+        method,
+        uri,
+        &canonical_query_string,
+        &canonical_headers,
+        &signed_headers,
+        content_sha256,
+    );
+    let string_to_sign = get_string_to_sign(date, &scope, &canonical_request_hash);
+    let signing_key = get_signing_key(cache, secret_key, date, region, "s3");
+    let signature = get_signature(&signing_key, string_to_sign.as_bytes());
+    let authorization = get_authorization(access_key, &scope, &signed_headers, &signature);
+
+    headers.add(AUTHORIZATION, authorization);
+
+    ChunkSigningContext {
+        signing_key,
+        date_time: to_amz_date(date),
+        scope,
+        seed_signature: signature,
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -762,4 +911,274 @@ mod tests {
 
         assert_eq!(sig1, sig2);
     }
+
+    // ===========================
+    // Chunk Signing Tests
+    // ===========================
+
+    #[test]
+    fn test_sign_chunk_produces_valid_signature() {
+        // Use signing key derived from AWS test credentials
+        let cache = test_cache();
+        let secret_key = "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY";
+        let date = get_test_date();
+        let region = "us-east-1";
+
+        let signing_key = get_signing_key(&cache, secret_key, date, region, "s3");
+        let date_time = "20130524T000000Z";
+        let scope = "20130524/us-east-1/s3/aws4_request";
+        let previous_signature = "4f232c4386841ef735655705268965c44a0e4690baa4adea153f7db9fa80a0a9";
+        // SHA256 of some test data
+        let chunk_hash = "bf718b6f653bebc184e1479f1935b8da974d701b893afcf49e701f3e2f9f9c5a";
+
+        let signature = sign_chunk(
+            &signing_key,
+            date_time,
+            scope,
+            previous_signature,
+            chunk_hash,
+        );
+
+        // Should produce 64 character hex signature
+        assert_eq!(signature.len(), 64);
+        assert!(signature.chars().all(|c| c.is_ascii_hexdigit()));
+    }
+
+    #[test]
+    fn test_sign_chunk_deterministic() {
+        let cache = test_cache();
+        let secret_key = "test_secret";
+        let date = get_test_date();
+        let region = "us-east-1";
+
+        let signing_key = get_signing_key(&cache, secret_key, date, region, "s3");
+        let date_time = "20130524T000000Z";
+        let scope = "20130524/us-east-1/s3/aws4_request";
+        let previous_signature = "abcd1234abcd1234abcd1234abcd1234abcd1234abcd1234abcd1234abcd1234";
+        let chunk_hash = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855";
+
+        let sig1 = sign_chunk(
+            &signing_key,
+            date_time,
+            scope,
+            previous_signature,
+            chunk_hash,
+        );
+        let sig2 = sign_chunk(
+            &signing_key,
+            date_time,
+            scope,
+            previous_signature,
+            chunk_hash,
+        );
+
+        assert_eq!(sig1, sig2);
+    }
+
+    #[test]
+    fn test_sign_chunk_empty_data() {
+        let cache = test_cache();
+        let secret_key = "test_secret";
+        let date = get_test_date();
+        let region = "us-east-1";
+
+        let signing_key = get_signing_key(&cache, secret_key, date, region, "s3");
+        let date_time = "20130524T000000Z";
+        let scope = "20130524/us-east-1/s3/aws4_request";
+        let previous_signature = "abcd1234abcd1234abcd1234abcd1234abcd1234abcd1234abcd1234abcd1234";
+        // SHA256 of empty data
+        let chunk_hash = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855";
+
+        let signature = sign_chunk(
+            &signing_key,
+            date_time,
+            scope,
+            previous_signature,
+            chunk_hash,
+        );
+
+        // Should still produce valid signature for empty chunk
+        assert_eq!(signature.len(), 64);
+        assert!(signature.chars().all(|c| c.is_ascii_hexdigit()));
+    }
+
+    #[test]
+    fn test_sign_chunk_chaining() {
+        let cache = test_cache();
+        let secret_key = "test_secret";
+        let date = get_test_date();
+        let region = "us-east-1";
+
+        let signing_key = get_signing_key(&cache, secret_key, date, region, "s3");
+        let date_time = "20130524T000000Z";
+        let scope = "20130524/us-east-1/s3/aws4_request";
+        let seed_signature = "seed1234seed1234seed1234seed1234seed1234seed1234seed1234seed1234";
+        let chunk1_hash = "aaaa1111aaaa1111aaaa1111aaaa1111aaaa1111aaaa1111aaaa1111aaaa1111";
+        let chunk2_hash = "bbbb2222bbbb2222bbbb2222bbbb2222bbbb2222bbbb2222bbbb2222bbbb2222";
+
+        // Sign first chunk with seed signature
+        let chunk1_sig = sign_chunk(&signing_key, date_time, scope, seed_signature, chunk1_hash);
+
+        // Sign second chunk with first chunk's signature
+        let chunk2_sig = sign_chunk(&signing_key, date_time, scope, &chunk1_sig, chunk2_hash);
+
+        // Signatures should be different
+        assert_ne!(chunk1_sig, chunk2_sig);
+
+        // Both should be valid hex
+        assert_eq!(chunk1_sig.len(), 64);
+        assert_eq!(chunk2_sig.len(), 64);
+    }
+
+    #[test]
+    fn test_sign_trailer_produces_valid_signature() {
+        let cache = test_cache();
+        let secret_key = "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY";
+        let date = get_test_date();
+        let region = "us-east-1";
+
+        let signing_key = get_signing_key(&cache, secret_key, date, region, "s3");
+        let date_time = "20130524T000000Z";
+        let scope = "20130524/us-east-1/s3/aws4_request";
+        let last_chunk_signature =
+            "b6c6ea8a5354eaf15b3cb7646744f4275b71ea724fed81ceb9323e279d449df9";
+        // SHA256 of "x-amz-checksum-crc32c:sOO8/Q==\n"
+        let canonical_trailers_hash =
+            "1e376db7e1a34a8ef1c4bcee131a2d60a1cb62503747488624e10995f448d774";
+
+        let signature = sign_trailer(
+            &signing_key,
+            date_time,
+            scope,
+            last_chunk_signature,
+            canonical_trailers_hash,
+        );
+
+        // Should produce 64 character hex signature
+        assert_eq!(signature.len(), 64);
+        assert!(signature.chars().all(|c| c.is_ascii_hexdigit()));
+    }
+
+    #[test]
+    fn test_sign_trailer_deterministic() {
+        let cache = test_cache();
+        let secret_key = "test_secret";
+        let date = get_test_date();
+        let region = "us-east-1";
+
+        let signing_key = get_signing_key(&cache, secret_key, date, region, "s3");
+        let date_time = "20130524T000000Z";
+        let scope = "20130524/us-east-1/s3/aws4_request";
+        let last_chunk_signature =
+            "abcd1234abcd1234abcd1234abcd1234abcd1234abcd1234abcd1234abcd1234";
+        let canonical_trailers_hash =
+            "1234abcd1234abcd1234abcd1234abcd1234abcd1234abcd1234abcd1234abcd";
+
+        let sig1 = sign_trailer(
+            &signing_key,
+            date_time,
+            scope,
+            last_chunk_signature,
+            canonical_trailers_hash,
+        );
+        let sig2 = sign_trailer(
+            &signing_key,
+            date_time,
+            scope,
+            last_chunk_signature,
+            canonical_trailers_hash,
+        );
+
+        assert_eq!(sig1, sig2);
+    }
+
+    #[test]
+    fn test_sign_v4_s3_with_context_returns_valid_context() {
+        let cache = test_cache();
+        let method = Method::PUT;
+        let uri = "/examplebucket/chunkObject.txt";
+        let region = "us-east-1";
+        let mut headers = Multimap::new();
+        let date = get_test_date();
+        let content_sha256 = "STREAMING-AWS4-HMAC-SHA256-PAYLOAD-TRAILER";
+        let access_key = "AKIAIOSFODNN7EXAMPLE";
+        let secret_key = "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY";
+
+        headers.add(HOST, "s3.amazonaws.com");
+        headers.add(X_AMZ_CONTENT_SHA256, content_sha256);
+        headers.add(X_AMZ_DATE, "20130524T000000Z");
+        headers.add("Content-Encoding", "aws-chunked");
+        headers.add("x-amz-decoded-content-length", "66560");
+        headers.add("x-amz-trailer", "x-amz-checksum-crc32c");
+
+        let query_params = Multimap::new();
+
+        let context = sign_v4_s3_with_context(
+            &cache,
+            &method,
+            uri,
+            region,
+            &mut headers,
+            &query_params,
+            access_key,
+            secret_key,
+            content_sha256,
+            date,
+        );
+
+        // Authorization header should be added
+        assert!(headers.contains_key("Authorization"));
+        let auth_header = headers.get("Authorization").unwrap();
+        assert!(auth_header.starts_with("AWS4-HMAC-SHA256"));
+
+        // Context should have valid values
+        assert!(!context.signing_key.is_empty());
+        assert_eq!(context.date_time, "20130524T000000Z");
+        assert_eq!(context.scope, "20130524/us-east-1/s3/aws4_request");
+        assert_eq!(context.seed_signature.len(), 64);
+        assert!(
+            context
+                .seed_signature
+                .chars()
+                .all(|c| c.is_ascii_hexdigit())
+        );
+    }
+
+    #[test]
+    fn test_chunk_signing_context_can_be_cloned() {
+        let cache = test_cache();
+        let method = Method::PUT;
+        let uri = "/test";
+        let region = "us-east-1";
+        let mut headers = Multimap::new();
+        let date = get_test_date();
+        let content_sha256 = "STREAMING-AWS4-HMAC-SHA256-PAYLOAD-TRAILER";
+        let access_key = "test";
+        let secret_key = "secret";
+
+        headers.add(HOST, "s3.amazonaws.com");
+        headers.add(X_AMZ_CONTENT_SHA256, content_sha256);
+        headers.add(X_AMZ_DATE, "20130524T000000Z");
+
+        let query_params = Multimap::new();
+
+        let context = sign_v4_s3_with_context(
+            &cache,
+            &method,
+            uri,
+            region,
+            &mut headers,
+            &query_params,
+            access_key,
+            secret_key,
+            content_sha256,
+            date,
+        );
+
+        // Should be cloneable (required for async streams)
+        let cloned = context.clone();
+        assert_eq!(context.date_time, cloned.date_time);
+        assert_eq!(context.scope, cloned.scope);
+        assert_eq!(context.seed_signature, cloned.seed_signature);
+    }
 }

src/s3/types/basic_types.rs

@@ -16,7 +16,7 @@
 //! Basic S3 data types: ListEntry, Bucket, Part, Retention, etc.
 
 use crate::s3::error::ValidationErr;
-use crate::s3::utils::UtcTime;
+use crate::s3::utils::{ChecksumAlgorithm, UtcTime};
 use std::collections::HashMap;
 use std::fmt;
 
@@ -53,11 +53,34 @@ pub struct Part {
     pub etag: String,
 }
 
+/// Contains part information for multipart uploads including optional checksum.
+///
+/// Only one checksum algorithm is active per upload, so the checksum is stored
+/// as an optional tuple of (algorithm, base64-encoded value).
 #[derive(Clone, Debug)]
 pub struct PartInfo {
     pub number: u16,
     pub etag: String,
     pub size: u64,
+    /// Optional checksum for this part: (algorithm, base64-encoded value)
+    pub checksum: Option<(ChecksumAlgorithm, String)>,
+}
+
+impl PartInfo {
+    /// Creates a new PartInfo.
+    pub fn new(
+        number: u16,
+        etag: String,
+        size: u64,
+        checksum: Option<(ChecksumAlgorithm, String)>,
+    ) -> Self {
+        Self {
+            number,
+            etag,
+            size,
+            checksum,
+        }
+    }
 }
 
 #[derive(PartialEq, Clone, Debug)]

src/s3/types/header_constants.rs

@@ -105,3 +105,31 @@ pub const X_AMZ_COPY_SOURCE_SERVER_SIDE_ENCRYPTION_CUSTOMER_KEY: &str =
 
 pub const X_AMZ_COPY_SOURCE_SERVER_SIDE_ENCRYPTION_CUSTOMER_KEY_MD5: &str =
     "X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key-MD5";
+
+pub const X_AMZ_CHECKSUM_ALGORITHM: &str = "X-Amz-Checksum-Algorithm";
+
+pub const X_AMZ_CHECKSUM_CRC32: &str = "X-Amz-Checksum-CRC32";
+
+pub const X_AMZ_CHECKSUM_CRC32C: &str = "X-Amz-Checksum-CRC32C";
+
+pub const X_AMZ_CHECKSUM_SHA1: &str = "X-Amz-Checksum-SHA1";
+
+pub const X_AMZ_CHECKSUM_SHA256: &str = "X-Amz-Checksum-SHA256";
+
+pub const X_AMZ_CHECKSUM_CRC64NVME: &str = "X-Amz-Checksum-CRC64NVME";
+
+pub const X_AMZ_CHECKSUM_TYPE: &str = "X-Amz-Checksum-Type";
+
+pub const X_AMZ_TRAILER: &str = "X-Amz-Trailer";
+
+pub const X_AMZ_DECODED_CONTENT_LENGTH: &str = "X-Amz-Decoded-Content-Length";
+
+pub const CONTENT_ENCODING: &str = "Content-Encoding";
+
+/// Content-SHA256 value for streaming uploads with unsigned payload and trailing checksum
+pub const STREAMING_UNSIGNED_PAYLOAD_TRAILER: &str = "STREAMING-UNSIGNED-PAYLOAD-TRAILER";
+
+/// Content-SHA256 value for streaming uploads with signed payload and trailing checksum.
+/// Each chunk is signed with AWS Signature V4, and the trailer includes a trailer signature.
+pub const STREAMING_AWS4_HMAC_SHA256_PAYLOAD_TRAILER: &str =
+    "STREAMING-AWS4-HMAC-SHA256-PAYLOAD-TRAILER";

src/s3/types/s3_request.rs

@@ -19,6 +19,7 @@ use super::super::client::{DEFAULT_REGION, MinioClient};
 use crate::s3::error::Error;
 use crate::s3::multimap_ext::Multimap;
 use crate::s3::segmented_bytes::SegmentedBytes;
+use crate::s3::utils::ChecksumAlgorithm;
 use http::Method;
 use std::sync::Arc;
 use typed_builder::TypedBuilder;
@@ -50,6 +51,20 @@ pub struct S3Request {
     #[builder(default, setter(into))]
     body: Option<Arc<SegmentedBytes>>,
 
+    /// Optional trailing checksum algorithm for streaming uploads.
+    ///
+    /// When set, the request body will be sent using aws-chunked encoding
+    /// with the checksum computed incrementally and appended as a trailer.
+    #[builder(default)]
+    pub(crate) trailing_checksum: Option<ChecksumAlgorithm>,
+
+    /// When true and trailing checksums are enabled, signs each chunk with AWS Signature V4.
+    ///
+    /// Uses STREAMING-AWS4-HMAC-SHA256-PAYLOAD-TRAILER where each chunk is signed
+    /// and the trailer includes a trailer signature.
+    #[builder(default = false)]
+    pub(crate) use_signed_streaming: bool,
+
     /// region computed by [`S3Request::execute`]
     #[builder(default, setter(skip))]
     pub(crate) inner_region: String,
@@ -76,6 +91,8 @@ impl S3Request {
                 &self.bucket.as_deref(),
                 &self.object.as_deref(),
                 self.body.as_ref().map(Arc::clone),
+                self.trailing_checksum,
+                self.use_signed_streaming,
             )
             .await
     }

src/s3/utils.rs

@@ -20,19 +20,21 @@ use crate::s3::segmented_bytes::SegmentedBytes;
 use crate::s3::sse::{Sse, SseCustomerKey};
 use base64::engine::Engine as _;
 use chrono::{DateTime, Datelike, NaiveDateTime, Utc};
-use crc::{CRC_32_ISO_HDLC, Crc};
+use crc_fast::{CrcAlgorithm, Digest as CrcFastDigest, checksum as crc_fast_checksum};
 use lazy_static::lazy_static;
 use percent_encoding::{AsciiSet, NON_ALPHANUMERIC, percent_decode_str, utf8_percent_encode};
 use regex::Regex;
 #[cfg(feature = "ring")]
 use ring::digest::{Context, SHA256};
+use sha1::{Digest as Sha1Digest, Sha1};
 #[cfg(not(feature = "ring"))]
-use sha2::{Digest, Sha256};
+use sha2::Sha256;
 use std::collections::HashMap;
+use std::str::FromStr;
 use std::sync::Arc;
 use xmltree::Element;
 
-/// Date and time with UTC timezone
+/// Date and time with UTC timezone.
 pub type UtcTime = DateTime<Utc>;
 
 // Great stuff to get confused about.
@@ -60,10 +62,20 @@ pub fn b64_encode(input: impl AsRef<[u8]>) -> String {
     base64::engine::general_purpose::STANDARD.encode(input)
 }
 
-/// Computes CRC32 of given data.
+/// Computes CRC32 of given data using hardware-accelerated SIMD implementation.
+///
+/// Uses crc-fast which provides hardware acceleration via PCLMULQDQ/CLMUL instructions
+/// on modern CPUs, achieving >50 GiB/s throughput (vs ~0.5 GiB/s for software).
 pub fn crc32(data: &[u8]) -> u32 {
-    //TODO creating a new Crc object is expensive, we should cache it
+    crc_fast_checksum(CrcAlgorithm::Crc32IsoHdlc, data) as u32
-    Crc::<u32>::new(&CRC_32_ISO_HDLC).checksum(data)
+}
+
+/// Computes CRC64-NVME of given data using hardware-accelerated SIMD implementation.
+///
+/// Uses crc-fast which provides hardware acceleration via PCLMULQDQ/CLMUL instructions
+/// on modern CPUs, achieving >50 GiB/s throughput (vs ~0.5 GiB/s for software).
+pub fn crc64nvme(data: &[u8]) -> u64 {
+    crc_fast_checksum(CrcAlgorithm::Crc64Nvme, data)
 }
 
 /// Converts data array into 32-bit BigEndian unsigned int.
@@ -168,9 +180,252 @@ pub fn sha256_hash_sb(sb: Arc<SegmentedBytes>) -> String {
     }
 }
 
+/// S3 checksum algorithms supported by the API
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ChecksumAlgorithm {
+    CRC32,
+    CRC32C,
+    SHA1,
+    SHA256,
+    CRC64NVME,
+}
+
+impl ChecksumAlgorithm {
+    /// Returns the AWS header value for this checksum algorithm.
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            ChecksumAlgorithm::CRC32 => "CRC32",
+            ChecksumAlgorithm::CRC32C => "CRC32C",
+            ChecksumAlgorithm::SHA1 => "SHA1",
+            ChecksumAlgorithm::SHA256 => "SHA256",
+            ChecksumAlgorithm::CRC64NVME => "CRC64NVME",
+        }
+    }
+
+    /// Returns the HTTP header name for this checksum algorithm (e.g., "X-Amz-Checksum-CRC32").
+    pub fn header_name(&self) -> &'static str {
+        use crate::s3::types::header_constants::*;
+        match self {
+            ChecksumAlgorithm::CRC32 => X_AMZ_CHECKSUM_CRC32,
+            ChecksumAlgorithm::CRC32C => X_AMZ_CHECKSUM_CRC32C,
+            ChecksumAlgorithm::SHA1 => X_AMZ_CHECKSUM_SHA1,
+            ChecksumAlgorithm::SHA256 => X_AMZ_CHECKSUM_SHA256,
+            ChecksumAlgorithm::CRC64NVME => X_AMZ_CHECKSUM_CRC64NVME,
+        }
+    }
+}
+
+/// Parses a checksum algorithm name from a string.
+///
+/// Case-insensitive parsing of S3 checksum algorithm names. Useful for parsing
+/// header values or configuration strings.
+///
+/// # Supported Values
+///
+/// - `"CRC32"` / `"crc32"` - Standard CRC32 checksum
+/// - `"CRC32C"` / `"crc32c"` - CRC32C (Castagnoli) checksum
+/// - `"SHA1"` / `"sha1"` - SHA-1 hash
+/// - `"SHA256"` / `"sha256"` - SHA-256 hash
+/// - `"CRC64NVME"` / `"crc64nvme"` - CRC-64/NVME checksum
+///
+/// # Errors
+///
+/// Returns an error string if the algorithm name is not recognized.
+impl FromStr for ChecksumAlgorithm {
+    type Err = String;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s.to_uppercase().as_str() {
+            "CRC32" => Ok(ChecksumAlgorithm::CRC32),
+            "CRC32C" => Ok(ChecksumAlgorithm::CRC32C),
+            "SHA1" => Ok(ChecksumAlgorithm::SHA1),
+            "SHA256" => Ok(ChecksumAlgorithm::SHA256),
+            "CRC64NVME" => Ok(ChecksumAlgorithm::CRC64NVME),
+            _ => Err(format!("Unknown checksum algorithm: {}", s)),
+        }
+    }
+}
+
+/// Computes CRC32C checksum (Castagnoli polynomial) and returns base64-encoded value.
+///
+/// Uses crc-fast which provides hardware acceleration via PCLMULQDQ/CLMUL instructions
+/// on modern CPUs, achieving >50 GiB/s throughput.
+pub fn crc32c(data: &[u8]) -> String {
+    let checksum = crc_fast_checksum(CrcAlgorithm::Crc32Iscsi, data) as u32;
+    b64_encode(checksum.to_be_bytes())
+}
+
+/// Computes SHA1 hash and returns base64-encoded value
+pub fn sha1_hash(data: &[u8]) -> String {
+    let mut hasher = Sha1::new();
+    hasher.update(data);
+    let result = hasher.finalize();
+    b64_encode(&result[..])
+}
+
+/// Computes SHA256 hash and returns base64-encoded value (for checksums, not authentication)
+pub fn sha256_checksum(data: &[u8]) -> String {
+    #[cfg(feature = "ring")]
+    {
+        b64_encode(ring::digest::digest(&SHA256, data).as_ref())
+    }
+    #[cfg(not(feature = "ring"))]
+    {
+        let result = Sha256::new_with_prefix(data).finalize();
+        b64_encode(&result[..])
+    }
+}
+
+/// Computes CRC32 checksum and returns base64-encoded value
+pub fn crc32_checksum(data: &[u8]) -> String {
+    b64_encode(crc32(data).to_be_bytes())
+}
+
+/// Computes CRC64-NVME checksum and returns base64-encoded value
+pub fn crc64nvme_checksum(data: &[u8]) -> String {
+    b64_encode(crc64nvme(data).to_be_bytes())
+}
+
+/// Computes checksum based on the specified algorithm for contiguous byte slices.
+///
+/// This function computes checksums on already-materialized `&[u8]` data. Use this when:
+/// - Data is already in a contiguous buffer (e.g., from `reqwest::Response::bytes()`)
+/// - Working with small byte arrays in tests
+/// - Data comes from sources other than `SegmentedBytes`
+///
+/// **Performance Note**: If you have data in `SegmentedBytes`, use [`compute_checksum_sb`]
+/// instead to avoid copying. Calling `.to_bytes()` on `SegmentedBytes` creates a full copy
+/// of all segments, which is expensive for large objects (up to 5GB per part).
+///
+/// # Arguments
+///
+/// * `algorithm` - The checksum algorithm to use (CRC32, CRC32C, CRC64NVME, SHA1, SHA256)
+/// * `data` - The contiguous byte slice to compute checksum over
+///
+/// # Returns
+///
+/// Base64-encoded checksum string suitable for S3 headers
+///
+/// # Example
+///
+/// ```
+/// use minio::s3::utils::{compute_checksum, ChecksumAlgorithm};
+///
+/// let data = b"hello world";
+/// let checksum = compute_checksum(ChecksumAlgorithm::CRC32C, data);
+/// println!("CRC32C: {}", checksum);
+/// ```
+pub fn compute_checksum(algorithm: ChecksumAlgorithm, data: &[u8]) -> String {
+    match algorithm {
+        ChecksumAlgorithm::CRC32 => crc32_checksum(data),
+        ChecksumAlgorithm::CRC32C => crc32c(data),
+        ChecksumAlgorithm::SHA1 => sha1_hash(data),
+        ChecksumAlgorithm::SHA256 => sha256_checksum(data),
+        ChecksumAlgorithm::CRC64NVME => crc64nvme_checksum(data),
+    }
+}
+
+/// Computes checksum for `SegmentedBytes` without copying data (zero-copy streaming).
+///
+/// This function computes checksums by iterating over segments incrementally, avoiding
+/// the need to materialize the entire buffer in contiguous memory. This is critical for
+/// performance when working with large objects (up to 5GB per part in multipart uploads).
+///
+/// **Always use this function for `SegmentedBytes` data** instead of calling `.to_bytes()`
+/// followed by `compute_checksum()`, which would create an expensive full copy.
+///
+/// # Performance Characteristics
+///
+/// - **Memory**: Only allocates hasher state (~64 bytes for SHA256, ~4-8 bytes for CRC)
+/// - **CPU**: Hardware-accelerated where available (CRC32C with SSE 4.2)
+/// - **Streaming**: Processes data incrementally without buffering
+///
+/// # Arguments
+///
+/// * `algorithm` - The checksum algorithm to use (CRC32, CRC32C, CRC64NVME, SHA1, SHA256)
+/// * `sb` - The segmented bytes to compute checksum over (passed by reference, not consumed)
+///
+/// # Returns
+///
+/// Base64-encoded checksum string suitable for S3 headers
+///
+/// # Example
+///
+/// ```
+/// use minio::s3::utils::{compute_checksum_sb, ChecksumAlgorithm};
+/// use minio::s3::segmented_bytes::SegmentedBytes;
+/// use std::sync::Arc;
+/// use bytes::Bytes;
+///
+/// let mut sb = SegmentedBytes::new();
+/// sb.append(Bytes::from("hello "));
+/// sb.append(Bytes::from("world"));
+/// let sb = Arc::new(sb);
+///
+/// let checksum = compute_checksum_sb(ChecksumAlgorithm::CRC32C, &sb);
+/// println!("CRC32C: {}", checksum);
+/// ```
+///
+/// # See Also
+///
+/// - [`compute_checksum`] - For already-contiguous `&[u8]` data
+pub fn compute_checksum_sb(algorithm: ChecksumAlgorithm, sb: &Arc<SegmentedBytes>) -> String {
+    match algorithm {
+        ChecksumAlgorithm::CRC32 => {
+            let mut digest = CrcFastDigest::new(CrcAlgorithm::Crc32IsoHdlc);
+            for data in sb.iter() {
+                digest.update(data.as_ref());
+            }
+            b64_encode((digest.finalize() as u32).to_be_bytes())
+        }
+        ChecksumAlgorithm::CRC32C => {
+            let mut digest = CrcFastDigest::new(CrcAlgorithm::Crc32Iscsi);
+            for data in sb.iter() {
+                digest.update(data.as_ref());
+            }
+            b64_encode((digest.finalize() as u32).to_be_bytes())
+        }
+        ChecksumAlgorithm::SHA1 => {
+            let mut hasher = Sha1::new();
+            for data in sb.iter() {
+                hasher.update(data.as_ref());
+            }
+            let result = hasher.finalize();
+            b64_encode(&result[..])
+        }
+        ChecksumAlgorithm::SHA256 => {
+            #[cfg(feature = "ring")]
+            {
+                let mut context = Context::new(&SHA256);
+                for data in sb.iter() {
+                    context.update(data.as_ref());
+                }
+                b64_encode(context.finish().as_ref())
+            }
+            #[cfg(not(feature = "ring"))]
+            {
+                let mut hasher = Sha256::new();
+                for data in sb.iter() {
+                    hasher.update(data.as_ref());
+                }
+                let result = hasher.finalize();
+                b64_encode(&result[..])
+            }
+        }
+        ChecksumAlgorithm::CRC64NVME => {
+            let mut digest = CrcFastDigest::new(CrcAlgorithm::Crc64Nvme);
+            for data in sb.iter() {
+                digest.update(data.as_ref());
+            }
+            b64_encode(digest.finalize().to_be_bytes())
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
+    use bytes::Bytes;
     use std::collections::HashMap;
 
     #[test]
@@ -290,6 +545,93 @@ mod tests {
         assert_eq!(empty_hash, "1B2M2Y8AsgTpgAmY7PhCfg==");
     }
 
+    #[test]
+    fn test_crc32c() {
+        let checksum = crc32c(b"hello");
+        assert!(!checksum.is_empty());
+        let checksum_empty = crc32c(b"");
+        assert!(!checksum_empty.is_empty());
+        let checksum_standard = crc32c(b"123456789");
+        assert!(!checksum_standard.is_empty());
+    }
+
+    #[test]
+    fn test_sha1_hash() {
+        let hash = sha1_hash(b"hello");
+        assert!(!hash.is_empty());
+        let hash_empty = sha1_hash(b"");
+        assert!(!hash_empty.is_empty());
+        let hash_fox = sha1_hash(b"The quick brown fox jumps over the lazy dog");
+        assert!(!hash_fox.is_empty());
+    }
+
+    #[test]
+    fn test_sha256_checksum() {
+        let checksum = sha256_checksum(b"hello");
+        assert!(!checksum.is_empty());
+        let checksum_empty = sha256_checksum(b"");
+        assert!(!checksum_empty.is_empty());
+    }
+
+    #[test]
+    fn test_crc32_checksum() {
+        let checksum = crc32_checksum(b"hello");
+        assert!(!checksum.is_empty());
+        let checksum_empty = crc32_checksum(b"");
+        assert_eq!(checksum_empty, "AAAAAA==");
+        let checksum_standard = crc32_checksum(b"123456789");
+        assert!(!checksum_standard.is_empty());
+    }
+
+    #[test]
+    fn test_checksum_algorithm_as_str() {
+        assert_eq!(ChecksumAlgorithm::CRC32.as_str(), "CRC32");
+        assert_eq!(ChecksumAlgorithm::CRC32C.as_str(), "CRC32C");
+        assert_eq!(ChecksumAlgorithm::SHA1.as_str(), "SHA1");
+        assert_eq!(ChecksumAlgorithm::SHA256.as_str(), "SHA256");
+    }
+
+    #[test]
+    fn test_checksum_algorithm_from_str() {
+        assert_eq!(
+            "CRC32".parse::<ChecksumAlgorithm>().unwrap(),
+            ChecksumAlgorithm::CRC32
+        );
+        assert_eq!(
+            "crc32c".parse::<ChecksumAlgorithm>().unwrap(),
+            ChecksumAlgorithm::CRC32C
+        );
+        assert_eq!(
+            "SHA1".parse::<ChecksumAlgorithm>().unwrap(),
+            ChecksumAlgorithm::SHA1
+        );
+        assert_eq!(
+            "sha256".parse::<ChecksumAlgorithm>().unwrap(),
+            ChecksumAlgorithm::SHA256
+        );
+        assert!("invalid".parse::<ChecksumAlgorithm>().is_err());
+    }
+
+    #[test]
+    fn test_compute_checksum() {
+        let data = b"hello world";
+
+        let crc32_result = compute_checksum(ChecksumAlgorithm::CRC32, data);
+        assert!(!crc32_result.is_empty());
+
+        let crc32c_result = compute_checksum(ChecksumAlgorithm::CRC32C, data);
+        assert!(!crc32c_result.is_empty());
+
+        let sha1_result = compute_checksum(ChecksumAlgorithm::SHA1, data);
+        assert!(!sha1_result.is_empty());
+
+        let sha256_result = compute_checksum(ChecksumAlgorithm::SHA256, data);
+        assert!(!sha256_result.is_empty());
+
+        assert_ne!(crc32_result, crc32c_result);
+        assert_ne!(sha1_result, sha256_result);
+    }
+
     #[test]
     fn test_parse_bool_true() {
         assert!(parse_bool("true").unwrap());
@@ -564,6 +906,7 @@ mod tests {
     #[test]
     fn test_match_region_basic() {
         let _result = match_region("us-east-1");
+        // TODO consider fixing or removing this test
         // Test that match_region returns a boolean (always true)
     }
 
@@ -647,6 +990,36 @@ mod tests {
         let tags = parse_tags("Environment=Production").unwrap();
         assert!(!tags.is_empty());
     }
+
+    #[test]
+    fn test_compute_checksum_sb_matches_compute_checksum() {
+        // Test data
+        let test_data = b"The quick brown fox jumps over the lazy dog";
+
+        // Create SegmentedBytes with multiple segments to test incremental computation
+        let mut sb = SegmentedBytes::new();
+        sb.append(Bytes::from(&test_data[0..10]));
+        sb.append(Bytes::from(&test_data[10..25]));
+        sb.append(Bytes::from(&test_data[25..]));
+        let sb = Arc::new(sb);
+
+        // Test all algorithms
+        for algo in [
+            ChecksumAlgorithm::CRC32,
+            ChecksumAlgorithm::CRC32C,
+            ChecksumAlgorithm::CRC64NVME,
+            ChecksumAlgorithm::SHA1,
+            ChecksumAlgorithm::SHA256,
+        ] {
+            let from_bytes = compute_checksum(algo, test_data);
+            let from_sb = compute_checksum_sb(algo, &sb);
+            assert_eq!(
+                from_bytes, from_sb,
+                "Mismatch for {:?}: bytes='{}' vs sb='{}'",
+                algo, from_bytes, from_sb
+            );
+        }
+    }
 }
 
 /// Gets base64-encoded MD5 hash of given data.

tests/s3/mod.rs

@@ -21,10 +21,12 @@ mod client_config;
 // Object operations
 mod append_object;
 mod get_object;
+mod object_checksums;
 mod object_compose;
 mod object_copy;
 mod object_delete;
 mod object_put;
+mod test_checksums;
 mod upload_download_object;
 
 // Bucket operations

tests/s3/test_checksums.rs

@@ -0,0 +1,267 @@
+// MinIO Rust Library for Amazon S3 Compatible Cloud Storage
+// Copyright 2025 MinIO, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use minio::s3::utils::{
+    ChecksumAlgorithm, compute_checksum, crc32_checksum, crc32c, crc64nvme_checksum, sha1_hash,
+    sha256_checksum,
+};
+
+/// Test CRC32 checksum computation
+#[test]
+fn test_crc32_checksum() {
+    let data = b"Hello, World!";
+    let checksum = crc32_checksum(data);
+
+    // Verify it's base64 encoded
+    assert!(!checksum.is_empty());
+    assert!(base64::Engine::decode(&base64::engine::general_purpose::STANDARD, &checksum).is_ok());
+}
+
+/// Test CRC32C checksum computation
+#[test]
+fn test_crc32c_checksum() {
+    let data = b"Hello, World!";
+    let checksum = crc32c(data);
+
+    // Verify it's base64 encoded
+    assert!(!checksum.is_empty());
+    assert!(base64::Engine::decode(&base64::engine::general_purpose::STANDARD, &checksum).is_ok());
+}
+
+/// Test CRC64-NVME checksum computation
+#[test]
+fn test_crc64nvme_checksum() {
+    let data = b"Hello, World!";
+    let checksum = crc64nvme_checksum(data);
+
+    // Verify it's base64 encoded
+    assert!(!checksum.is_empty());
+    assert!(base64::Engine::decode(&base64::engine::general_purpose::STANDARD, &checksum).is_ok());
+
+    // Verify it's different from CRC32/CRC32C (different algorithms produce different results)
+    let crc32_result = crc32_checksum(data);
+    assert_ne!(checksum, crc32_result);
+}
+
+/// Test SHA1 hash computation
+#[test]
+fn test_sha1_hash() {
+    let data = b"Hello, World!";
+    let hash = sha1_hash(data);
+
+    // Verify it's base64 encoded
+    assert!(!hash.is_empty());
+    assert!(base64::Engine::decode(&base64::engine::general_purpose::STANDARD, &hash).is_ok());
+}
+
+/// Test SHA256 checksum computation
+#[test]
+fn test_sha256_checksum() {
+    let data = b"Hello, World!";
+    let checksum = sha256_checksum(data);
+
+    // Verify it's base64 encoded
+    assert!(!checksum.is_empty());
+    assert!(base64::Engine::decode(&base64::engine::general_purpose::STANDARD, &checksum).is_ok());
+}
+
+/// Test compute_checksum with all algorithms
+#[test]
+fn test_compute_checksum_all_algorithms() {
+    let data = b"Test data for checksums";
+
+    let crc32 = compute_checksum(ChecksumAlgorithm::CRC32, data);
+    let crc32c = compute_checksum(ChecksumAlgorithm::CRC32C, data);
+    let crc64nvme = compute_checksum(ChecksumAlgorithm::CRC64NVME, data);
+    let sha1 = compute_checksum(ChecksumAlgorithm::SHA1, data);
+    let sha256 = compute_checksum(ChecksumAlgorithm::SHA256, data);
+
+    // All should be non-empty and valid base64
+    for checksum in [&crc32, &crc32c, &crc64nvme, &sha1, &sha256] {
+        assert!(!checksum.is_empty());
+        assert!(
+            base64::Engine::decode(&base64::engine::general_purpose::STANDARD, checksum).is_ok()
+        );
+    }
+
+    // All should be different (different algorithms)
+    assert_ne!(crc32, crc32c);
+    assert_ne!(crc32, crc64nvme);
+    assert_ne!(crc32, sha1);
+    assert_ne!(crc32, sha256);
+    assert_ne!(crc32c, crc64nvme);
+}
+
+/// Test that different data produces different checksums
+#[test]
+fn test_different_data_different_checksums() {
+    let data1 = b"First test data";
+    let data2 = b"Second test data";
+
+    // Test with each algorithm
+    for algorithm in [
+        ChecksumAlgorithm::CRC32,
+        ChecksumAlgorithm::CRC32C,
+        ChecksumAlgorithm::CRC64NVME,
+        ChecksumAlgorithm::SHA1,
+        ChecksumAlgorithm::SHA256,
+    ] {
+        let checksum1 = compute_checksum(algorithm, data1);
+        let checksum2 = compute_checksum(algorithm, data2);
+        assert_ne!(
+            checksum1, checksum2,
+            "Algorithm {:?} produced same checksum for different data",
+            algorithm
+        );
+    }
+}
+
+/// Test that same data produces same checksums (deterministic)
+#[test]
+fn test_deterministic_checksums() {
+    let data = b"Deterministic test data";
+
+    for algorithm in [
+        ChecksumAlgorithm::CRC32,
+        ChecksumAlgorithm::CRC32C,
+        ChecksumAlgorithm::CRC64NVME,
+        ChecksumAlgorithm::SHA1,
+        ChecksumAlgorithm::SHA256,
+    ] {
+        let checksum1 = compute_checksum(algorithm, data);
+        let checksum2 = compute_checksum(algorithm, data);
+        assert_eq!(
+            checksum1, checksum2,
+            "Algorithm {:?} is not deterministic",
+            algorithm
+        );
+    }
+}
+
+/// Test empty data checksums
+#[test]
+fn test_empty_data_checksums() {
+    let data = b"";
+
+    for algorithm in [
+        ChecksumAlgorithm::CRC32,
+        ChecksumAlgorithm::CRC32C,
+        ChecksumAlgorithm::CRC64NVME,
+        ChecksumAlgorithm::SHA1,
+        ChecksumAlgorithm::SHA256,
+    ] {
+        let checksum = compute_checksum(algorithm, data);
+        // Empty data should still produce a valid checksum
+        assert!(!checksum.is_empty());
+        assert!(
+            base64::Engine::decode(&base64::engine::general_purpose::STANDARD, &checksum).is_ok()
+        );
+    }
+}
+
+/// Test large data checksums
+#[test]
+fn test_large_data_checksums() {
+    // Test with 1MB of data
+    let data = vec![0x42u8; 1024 * 1024];
+
+    for algorithm in [
+        ChecksumAlgorithm::CRC32,
+        ChecksumAlgorithm::CRC32C,
+        ChecksumAlgorithm::CRC64NVME,
+        ChecksumAlgorithm::SHA1,
+        ChecksumAlgorithm::SHA256,
+    ] {
+        let checksum = compute_checksum(algorithm, &data);
+        assert!(!checksum.is_empty());
+        assert!(
+            base64::Engine::decode(&base64::engine::general_purpose::STANDARD, &checksum).is_ok()
+        );
+    }
+}
+
+/// Test ChecksumAlgorithm::as_str()
+#[test]
+fn test_checksum_algorithm_as_str() {
+    assert_eq!(ChecksumAlgorithm::CRC32.as_str(), "CRC32");
+    assert_eq!(ChecksumAlgorithm::CRC32C.as_str(), "CRC32C");
+    assert_eq!(ChecksumAlgorithm::CRC64NVME.as_str(), "CRC64NVME");
+    assert_eq!(ChecksumAlgorithm::SHA1.as_str(), "SHA1");
+    assert_eq!(ChecksumAlgorithm::SHA256.as_str(), "SHA256");
+}
+
+/// Test ChecksumAlgorithm::from_str()
+#[test]
+fn test_checksum_algorithm_from_str() {
+    use std::str::FromStr;
+
+    // Test uppercase
+    assert_eq!(
+        ChecksumAlgorithm::from_str("CRC32").unwrap(),
+        ChecksumAlgorithm::CRC32
+    );
+    assert_eq!(
+        ChecksumAlgorithm::from_str("CRC32C").unwrap(),
+        ChecksumAlgorithm::CRC32C
+    );
+    assert_eq!(
+        ChecksumAlgorithm::from_str("CRC64NVME").unwrap(),
+        ChecksumAlgorithm::CRC64NVME
+    );
+    assert_eq!(
+        ChecksumAlgorithm::from_str("SHA1").unwrap(),
+        ChecksumAlgorithm::SHA1
+    );
+    assert_eq!(
+        ChecksumAlgorithm::from_str("SHA256").unwrap(),
+        ChecksumAlgorithm::SHA256
+    );
+
+    // Test lowercase
+    assert_eq!(
+        ChecksumAlgorithm::from_str("crc32").unwrap(),
+        ChecksumAlgorithm::CRC32
+    );
+    assert_eq!(
+        ChecksumAlgorithm::from_str("crc32c").unwrap(),
+        ChecksumAlgorithm::CRC32C
+    );
+    assert_eq!(
+        ChecksumAlgorithm::from_str("crc64nvme").unwrap(),
+        ChecksumAlgorithm::CRC64NVME
+    );
+    assert_eq!(
+        ChecksumAlgorithm::from_str("sha1").unwrap(),
+        ChecksumAlgorithm::SHA1
+    );
+    assert_eq!(
+        ChecksumAlgorithm::from_str("sha256").unwrap(),
+        ChecksumAlgorithm::SHA256
+    );
+
+    // Test mixed case
+    assert_eq!(
+        ChecksumAlgorithm::from_str("Crc32").unwrap(),
+        ChecksumAlgorithm::CRC32
+    );
+    assert_eq!(
+        ChecksumAlgorithm::from_str("Sha256").unwrap(),
+        ChecksumAlgorithm::SHA256
+    );
+
+    // Test invalid
+    assert!(ChecksumAlgorithm::from_str("INVALID").is_err());
+    assert!(ChecksumAlgorithm::from_str("MD5").is_err());
+}