[s3-checksum] implement x-amz-checksum-* headers

19 files changed, 1209 insertions, 333 deletions

diff --git a/src/api/Cargo.toml b/src/api/Cargo.toml
index bcf6a537..1b87496c 100644
--- a/src/api/Cargo.toml
+++ b/src/api/Cargo.toml
@@ -28,6 +28,8 @@ async-trait.workspace = true
 base64.workspace = true
 bytes.workspace = true
 chrono.workspace = true
+crc32fast.workspace = true
+crc32c.workspace = true
 crypto-common.workspace = true
 err-derive.workspace = true
 hex.workspace = true
@@ -37,6 +39,7 @@ tracing.workspace = true
 md-5.workspace = true
 nom.workspace = true
 pin-project.workspace = true
+sha1.workspace = true
 sha2.workspace = true
 
 futures.workspace = true
diff --git a/src/api/s3/api_server.rs b/src/api/s3/api_server.rs
index 1ed30996..1737af33 100644
--- a/src/api/s3/api_server.rs
+++ b/src/api/s3/api_server.rs
@@ -325,7 +325,7 @@ impl ApiHandler for S3ApiServer {
 					part_number_marker: part_number_marker.map(|p| p.min(10000)),
 					max_parts: max_parts.unwrap_or(1000).clamp(1, 1000),
 				};
-				handle_list_parts(ctx, &query).await
+				handle_list_parts(ctx, req, &query).await
 			}
 			Endpoint::DeleteObjects {} => handle_delete_objects(ctx, req, content_sha256).await,
 			Endpoint::GetBucketWebsite {} => handle_get_website(ctx).await,
diff --git a/src/api/s3/checksum.rs b/src/api/s3/checksum.rs
new file mode 100644
index 00000000..c9dc001c
--- /dev/null
+++ b/src/api/s3/checksum.rs
@@ -0,0 +1,406 @@
+use std::convert::{TryFrom, TryInto};
+use std::hash::Hasher;
+
+use base64::prelude::*;
+use crc32c::Crc32cHasher as Crc32c;
+use crc32fast::Hasher as Crc32;
+use md5::{Digest, Md5};
+use sha1::Sha1;
+use sha2::Sha256;
+
+use http::{HeaderMap, HeaderName, HeaderValue};
+
+use garage_util::data::*;
+use garage_util::error::OkOrMessage;
+
+use garage_model::s3::object_table::*;
+
+use crate::s3::error::*;
+
+pub const X_AMZ_CHECKSUM_ALGORITHM: HeaderName =
+	HeaderName::from_static("x-amz-checksum-algorithm");
+pub const X_AMZ_CHECKSUM_MODE: HeaderName = HeaderName::from_static("x-amz-checksum-mode");
+pub const X_AMZ_CHECKSUM_CRC32: HeaderName = HeaderName::from_static("x-amz-checksum-crc32");
+pub const X_AMZ_CHECKSUM_CRC32C: HeaderName = HeaderName::from_static("x-amz-checksum-crc32c");
+pub const X_AMZ_CHECKSUM_SHA1: HeaderName = HeaderName::from_static("x-amz-checksum-sha1");
+pub const X_AMZ_CHECKSUM_SHA256: HeaderName = HeaderName::from_static("x-amz-checksum-sha256");
+
+pub type Crc32Checksum = [u8; 4];
+pub type Crc32cChecksum = [u8; 4];
+pub type Md5Checksum = [u8; 16];
+pub type Sha1Checksum = [u8; 20];
+pub type Sha256Checksum = [u8; 32];
+
+#[derive(Debug, Default)]
+pub(crate) struct ExpectedChecksums {
+	// base64-encoded md5 (content-md5 header)
+	pub md5: Option<String>,
+	// content_sha256 (as a Hash / FixedBytes32)
+	pub sha256: Option<Hash>,
+	// extra x-amz-checksum-* header
+	pub extra: Option<ChecksumValue>,
+}
+
+pub(crate) struct Checksummer {
+	pub crc32: Option<Crc32>,
+	pub crc32c: Option<Crc32c>,
+	pub md5: Option<Md5>,
+	pub sha1: Option<Sha1>,
+	pub sha256: Option<Sha256>,
+}
+
+#[derive(Default)]
+pub(crate) struct Checksums {
+	pub crc32: Option<Crc32Checksum>,
+	pub crc32c: Option<Crc32cChecksum>,
+	pub md5: Option<Md5Checksum>,
+	pub sha1: Option<Sha1Checksum>,
+	pub sha256: Option<Sha256Checksum>,
+}
+
+impl Checksummer {
+	pub(crate) fn init(expected: &ExpectedChecksums, require_md5: bool) -> Self {
+		let mut ret = Self {
+			crc32: None,
+			crc32c: None,
+			md5: None,
+			sha1: None,
+			sha256: None,
+		};
+
+		if expected.md5.is_some() || require_md5 {
+			ret.md5 = Some(Md5::new());
+		}
+		if expected.sha256.is_some() || matches!(&expected.extra, Some(ChecksumValue::Sha256(_))) {
+			ret.sha256 = Some(Sha256::new());
+		}
+		if matches!(&expected.extra, Some(ChecksumValue::Crc32(_))) {
+			ret.crc32 = Some(Crc32::new());
+		}
+		if matches!(&expected.extra, Some(ChecksumValue::Crc32c(_))) {
+			ret.crc32c = Some(Crc32c::default());
+		}
+		if matches!(&expected.extra, Some(ChecksumValue::Sha1(_))) {
+			ret.sha1 = Some(Sha1::new());
+		}
+		ret
+	}
+
+	pub(crate) fn add(mut self, algo: Option<ChecksumAlgorithm>) -> Self {
+		match algo {
+			Some(ChecksumAlgorithm::Crc32) => {
+				self.crc32 = Some(Crc32::new());
+			}
+			Some(ChecksumAlgorithm::Crc32c) => {
+				self.crc32c = Some(Crc32c::default());
+			}
+			Some(ChecksumAlgorithm::Sha1) => {
+				self.sha1 = Some(Sha1::new());
+			}
+			Some(ChecksumAlgorithm::Sha256) => {
+				self.sha256 = Some(Sha256::new());
+			}
+			None => (),
+		}
+		self
+	}
+
+	pub(crate) fn update(&mut self, bytes: &[u8]) {
+		if let Some(crc32) = &mut self.crc32 {
+			crc32.update(bytes);
+		}
+		if let Some(crc32c) = &mut self.crc32c {
+			crc32c.write(bytes);
+		}
+		if let Some(md5) = &mut self.md5 {
+			md5.update(bytes);
+		}
+		if let Some(sha1) = &mut self.sha1 {
+			sha1.update(bytes);
+		}
+		if let Some(sha256) = &mut self.sha256 {
+			sha256.update(bytes);
+		}
+	}
+
+	pub(crate) fn finalize(self) -> Checksums {
+		Checksums {
+			crc32: self.crc32.map(|x| u32::to_be_bytes(x.finalize())),
+			crc32c: self
+				.crc32c
+				.map(|x| u32::to_be_bytes(u32::try_from(x.finish()).unwrap())),
+			md5: self.md5.map(|x| x.finalize()[..].try_into().unwrap()),
+			sha1: self.sha1.map(|x| x.finalize()[..].try_into().unwrap()),
+			sha256: self.sha256.map(|x| x.finalize()[..].try_into().unwrap()),
+		}
+	}
+}
+
+impl Checksums {
+	pub fn verify(&self, expected: &ExpectedChecksums) -> Result<(), Error> {
+		if let Some(expected_md5) = &expected.md5 {
+			match self.md5 {
+				Some(md5) if BASE64_STANDARD.encode(&md5) == expected_md5.trim_matches('"') => (),
+				_ => {
+					return Err(Error::InvalidDigest(
+						"MD5 checksum verification failed (from content-md5)".into(),
+					))
+				}
+			}
+		}
+		if let Some(expected_sha256) = &expected.sha256 {
+			match self.sha256 {
+				Some(sha256) if &sha256[..] == expected_sha256.as_slice() => (),
+				_ => {
+					return Err(Error::InvalidDigest(
+						"SHA256 checksum verification failed (from x-amz-content-sha256)".into(),
+					))
+				}
+			}
+		}
+		if let Some(extra) = expected.extra {
+			let algo = extra.algorithm();
+			if self.extract(Some(algo)) != Some(extra) {
+				return Err(Error::InvalidDigest(format!(
+					"Failed to validate checksum for algorithm {:?}",
+					algo
+				)));
+			}
+		}
+		Ok(())
+	}
+
+	pub fn extract(&self, algo: Option<ChecksumAlgorithm>) -> Option<ChecksumValue> {
+		match algo {
+			None => None,
+			Some(ChecksumAlgorithm::Crc32) => Some(ChecksumValue::Crc32(self.crc32.unwrap())),
+			Some(ChecksumAlgorithm::Crc32c) => Some(ChecksumValue::Crc32c(self.crc32c.unwrap())),
+			Some(ChecksumAlgorithm::Sha1) => Some(ChecksumValue::Sha1(self.sha1.unwrap())),
+			Some(ChecksumAlgorithm::Sha256) => Some(ChecksumValue::Sha256(self.sha256.unwrap())),
+		}
+	}
+}
+
+// ----
+
+#[derive(Default)]
+pub(crate) struct MultipartChecksummer {
+	pub md5: Md5,
+	pub extra: Option<MultipartExtraChecksummer>,
+}
+
+pub(crate) enum MultipartExtraChecksummer {
+	Crc32(Crc32),
+	Crc32c(Crc32c),
+	Sha1(Sha1),
+	Sha256(Sha256),
+}
+
+impl MultipartChecksummer {
+	pub(crate) fn init(algo: Option<ChecksumAlgorithm>) -> Self {
+		Self {
+			md5: Md5::new(),
+			extra: match algo {
+				None => None,
+				Some(ChecksumAlgorithm::Crc32) => {
+					Some(MultipartExtraChecksummer::Crc32(Crc32::new()))
+				}
+				Some(ChecksumAlgorithm::Crc32c) => {
+					Some(MultipartExtraChecksummer::Crc32c(Crc32c::default()))
+				}
+				Some(ChecksumAlgorithm::Sha1) => Some(MultipartExtraChecksummer::Sha1(Sha1::new())),
+				Some(ChecksumAlgorithm::Sha256) => {
+					Some(MultipartExtraChecksummer::Sha256(Sha256::new()))
+				}
+			},
+		}
+	}
+
+	pub(crate) fn update(
+		&mut self,
+		etag: &str,
+		checksum: Option<ChecksumValue>,
+	) -> Result<(), Error> {
+		self.md5
+			.update(&hex::decode(&etag).ok_or_message("invalid etag hex")?);
+		match (&mut self.extra, checksum) {
+			(None, _) => (),
+			(
+				Some(MultipartExtraChecksummer::Crc32(ref mut crc32)),
+				Some(ChecksumValue::Crc32(x)),
+			) => {
+				crc32.update(&x);
+			}
+			(
+				Some(MultipartExtraChecksummer::Crc32c(ref mut crc32c)),
+				Some(ChecksumValue::Crc32c(x)),
+			) => {
+				crc32c.write(&x);
+			}
+			(Some(MultipartExtraChecksummer::Sha1(ref mut sha1)), Some(ChecksumValue::Sha1(x))) => {
+				sha1.update(&x);
+			}
+			(
+				Some(MultipartExtraChecksummer::Sha256(ref mut sha256)),
+				Some(ChecksumValue::Sha256(x)),
+			) => {
+				sha256.update(&x);
+			}
+			(Some(_), b) => {
+				return Err(Error::internal_error(format!(
+					"part checksum was not computed correctly, got: {:?}",
+					b
+				)))
+			}
+		}
+		Ok(())
+	}
+
+	pub(crate) fn finalize(self) -> (Md5Checksum, Option<ChecksumValue>) {
+		let md5 = self.md5.finalize()[..].try_into().unwrap();
+		let extra = match self.extra {
+			None => None,
+			Some(MultipartExtraChecksummer::Crc32(crc32)) => {
+				Some(ChecksumValue::Crc32(u32::to_be_bytes(crc32.finalize())))
+			}
+			Some(MultipartExtraChecksummer::Crc32c(crc32c)) => Some(ChecksumValue::Crc32c(
+				u32::to_be_bytes(u32::try_from(crc32c.finish()).unwrap()),
+			)),
+			Some(MultipartExtraChecksummer::Sha1(sha1)) => {
+				Some(ChecksumValue::Sha1(sha1.finalize()[..].try_into().unwrap()))
+			}
+			Some(MultipartExtraChecksummer::Sha256(sha256)) => Some(ChecksumValue::Sha256(
+				sha256.finalize()[..].try_into().unwrap(),
+			)),
+		};
+		(md5, extra)
+	}
+}
+
+// ----
+
+/// Extract the value of the x-amz-checksum-algorithm header
+pub(crate) fn request_checksum_algorithm(
+	headers: &HeaderMap<HeaderValue>,
+) -> Result<Option<ChecksumAlgorithm>, Error> {
+	match headers.get(X_AMZ_CHECKSUM_ALGORITHM) {
+		None => Ok(None),
+		Some(x) if x == "CRC32" => Ok(Some(ChecksumAlgorithm::Crc32)),
+		Some(x) if x == "CRC32C" => Ok(Some(ChecksumAlgorithm::Crc32c)),
+		Some(x) if x == "SHA1" => Ok(Some(ChecksumAlgorithm::Sha1)),
+		Some(x) if x == "SHA256" => Ok(Some(ChecksumAlgorithm::Sha256)),
+		_ => Err(Error::bad_request("invalid checksum algorithm")),
+	}
+}
+
+/// Extract the value of any of the x-amz-checksum-* headers
+pub(crate) fn request_checksum_value(
+	headers: &HeaderMap<HeaderValue>,
+) -> Result<Option<ChecksumValue>, Error> {
+	let mut ret = vec![];
+
+	if let Some(crc32_str) = headers.get(X_AMZ_CHECKSUM_CRC32) {
+		let crc32 = BASE64_STANDARD
+			.decode(&crc32_str)
+			.ok()
+			.and_then(|x| x.try_into().ok())
+			.ok_or_bad_request("invalid x-amz-checksum-crc32 header")?;
+		ret.push(ChecksumValue::Crc32(crc32))
+	}
+	if let Some(crc32c_str) = headers.get(X_AMZ_CHECKSUM_CRC32C) {
+		let crc32c = BASE64_STANDARD
+			.decode(&crc32c_str)
+			.ok()
+			.and_then(|x| x.try_into().ok())
+			.ok_or_bad_request("invalid x-amz-checksum-crc32c header")?;
+		ret.push(ChecksumValue::Crc32c(crc32c))
+	}
+	if let Some(sha1_str) = headers.get(X_AMZ_CHECKSUM_SHA1) {
+		let sha1 = BASE64_STANDARD
+			.decode(&sha1_str)
+			.ok()
+			.and_then(|x| x.try_into().ok())
+			.ok_or_bad_request("invalid x-amz-checksum-sha1 header")?;
+		ret.push(ChecksumValue::Sha1(sha1))
+	}
+	if let Some(sha256_str) = headers.get(X_AMZ_CHECKSUM_SHA256) {
+		let sha256 = BASE64_STANDARD
+			.decode(&sha256_str)
+			.ok()
+			.and_then(|x| x.try_into().ok())
+			.ok_or_bad_request("invalid x-amz-checksum-sha256 header")?;
+		ret.push(ChecksumValue::Sha256(sha256))
+	}
+
+	if ret.len() > 1 {
+		return Err(Error::bad_request(
+			"multiple x-amz-checksum-* headers given",
+		));
+	}
+	Ok(ret.pop())
+}
+
+/// Checks for the presense of x-amz-checksum-algorithm
+/// if so extract the corrseponding x-amz-checksum-* value
+pub(crate) fn request_checksum_algorithm_value(
+	headers: &HeaderMap<HeaderValue>,
+) -> Result<Option<ChecksumValue>, Error> {
+	match headers.get(X_AMZ_CHECKSUM_ALGORITHM) {
+		Some(x) if x == "CRC32" => {
+			let crc32 = headers
+				.get(X_AMZ_CHECKSUM_CRC32)
+				.and_then(|x| BASE64_STANDARD.decode(&x).ok())
+				.and_then(|x| x.try_into().ok())
+				.ok_or_bad_request("invalid x-amz-checksum-crc32 header")?;
+			Ok(Some(ChecksumValue::Crc32(crc32)))
+		}
+		Some(x) if x == "CRC32C" => {
+			let crc32c = headers
+				.get(X_AMZ_CHECKSUM_CRC32C)
+				.and_then(|x| BASE64_STANDARD.decode(&x).ok())
+				.and_then(|x| x.try_into().ok())
+				.ok_or_bad_request("invalid x-amz-checksum-crc32c header")?;
+			Ok(Some(ChecksumValue::Crc32c(crc32c)))
+		}
+		Some(x) if x == "SHA1" => {
+			let sha1 = headers
+				.get(X_AMZ_CHECKSUM_SHA1)
+				.and_then(|x| BASE64_STANDARD.decode(&x).ok())
+				.and_then(|x| x.try_into().ok())
+				.ok_or_bad_request("invalid x-amz-checksum-sha1 header")?;
+			Ok(Some(ChecksumValue::Sha1(sha1)))
+		}
+		Some(x) if x == "SHA256" => {
+			let sha256 = headers
+				.get(X_AMZ_CHECKSUM_SHA256)
+				.and_then(|x| BASE64_STANDARD.decode(&x).ok())
+				.and_then(|x| x.try_into().ok())
+				.ok_or_bad_request("invalid x-amz-checksum-sha256 header")?;
+			Ok(Some(ChecksumValue::Sha256(sha256)))
+		}
+		Some(_) => Err(Error::bad_request("invalid x-amz-checksum-algorithm")),
+		None => Ok(None),
+	}
+}
+
+pub(crate) fn add_checksum_response_headers(
+	checksum: &Option<ChecksumValue>,
+	mut resp: http::response::Builder,
+) -> http::response::Builder {
+	match checksum {
+		Some(ChecksumValue::Crc32(crc32)) => {
+			resp = resp.header(X_AMZ_CHECKSUM_CRC32, BASE64_STANDARD.encode(&crc32));
+		}
+		Some(ChecksumValue::Crc32c(crc32c)) => {
+			resp = resp.header(X_AMZ_CHECKSUM_CRC32C, BASE64_STANDARD.encode(&crc32c));
+		}
+		Some(ChecksumValue::Sha1(sha1)) => {
+			resp = resp.header(X_AMZ_CHECKSUM_SHA1, BASE64_STANDARD.encode(&sha1));
+		}
+		Some(ChecksumValue::Sha256(sha256)) => {
+			resp = resp.header(X_AMZ_CHECKSUM_SHA256, BASE64_STANDARD.encode(&sha256));
+		}
+		None => (),
+	}
+	resp
+}
diff --git a/src/api/s3/copy.rs b/src/api/s3/copy.rs
index 2b29ec6d..411a6917 100644
--- a/src/api/s3/copy.rs
+++ b/src/api/s3/copy.rs
@@ -2,7 +2,6 @@ use std::pin::Pin;
 use std::time::{Duration, SystemTime, UNIX_EPOCH};
 
 use futures::{stream, stream::Stream, StreamExt, TryStreamExt};
-use md5::{Digest as Md5Digest, Md5};
 
 use bytes::Bytes;
 use hyper::{Request, Response};
@@ -23,11 +22,12 @@ use garage_model::s3::version_table::*;
 
 use crate::helpers::*;
 use crate::s3::api_server::{ReqBody, ResBody};
+use crate::s3::checksum::*;
 use crate::s3::encryption::EncryptionParams;
 use crate::s3::error::*;
 use crate::s3::get::full_object_byte_stream;
 use crate::s3::multipart;
-use crate::s3::put::{get_headers, save_stream, SaveStreamResult};
+use crate::s3::put::{get_headers, save_stream, ChecksumMode, SaveStreamResult};
 use crate::s3::xml::{self as s3_xml, xmlns_tag};
 
 // -------- CopyObject ---------
@@ -39,6 +39,8 @@ pub async fn handle_copy(
 ) -> Result<Response<ResBody>, Error> {
 	let copy_precondition = CopyPreconditionHeaders::parse(req)?;
 
+	let checksum_algorithm = request_checksum_algorithm(req.headers())?;
+
 	let source_object = get_copy_source(&ctx, req).await?;
 
 	let (source_version, source_version_data, source_version_meta) =
@@ -48,7 +50,7 @@ pub async fn handle_copy(
 	copy_precondition.check(source_version, &source_version_meta.etag)?;
 
 	// Determine encryption parameters
-	let (source_encryption, source_object_headers) =
+	let (source_encryption, source_object_meta_inner) =
 		EncryptionParams::check_decrypt_for_copy_source(
 			&ctx.garage,
 			req.headers(),
@@ -56,23 +58,54 @@ pub async fn handle_copy(
 		)?;
 	let dest_encryption = EncryptionParams::new_from_headers(&ctx.garage, req.headers())?;
 
-	// Determine headers of destination object
-	let dest_object_headers = match req.headers().get("x-amz-metadata-directive") {
-		Some(v) if v == hyper::header::HeaderValue::from_static("REPLACE") => {
-			get_headers(req.headers())?
-		}
-		_ => source_object_headers.into_owned(),
+	// Extract source checksum info before source_object_meta_inner is consumed
+	let source_checksum = source_object_meta_inner.checksum;
+	let source_checksum_algorithm = source_checksum.map(|x| x.algorithm());
+
+	// If source object has a checksum, the destination object must as well.
+	// The x-amz-checksum-algorihtm header allows to change that algorithm,
+	// but if it is absent, we must use the same as before
+	let checksum_algorithm = checksum_algorithm.or(source_checksum_algorithm);
+
+	// Determine metadata of destination object
+	let was_multipart = source_version_meta.etag.contains('-');
+	let dest_object_meta = ObjectVersionMetaInner {
+		headers: match req.headers().get("x-amz-metadata-directive") {
+			Some(v) if v == hyper::header::HeaderValue::from_static("REPLACE") => {
+				get_headers(req.headers())?
+			}
+			_ => source_object_meta_inner.into_owned().headers,
+		},
+		checksum: source_checksum,
 	};
 
 	// Do actual object copying
-	let res = if EncryptionParams::is_same(&source_encryption, &dest_encryption) {
-		// If source and dest are both unencrypted, or if the encryption keys
-		// are the same, we can just copy the metadata and link blocks of the
+	//
+	// In any of the following scenarios, we need to read the whole object
+	// data and re-write it again:
+	//
+	// - the data needs to be decrypted or encrypted
+	// - the requested checksum algorithm requires us to recompute a checksum
+	// - the original object was a multipart upload and a checksum algorithm
+	//   is defined (AWS specifies that in this case, we must recompute the
+	//   checksum from scratch as if this was a single big object and not
+	//   a multipart object, as the checksums are not computed in the same way)
+	//
+	// In other cases, we can just copy the metadata and reference the same blocks.
+	//
+	// See: https://docs.aws.amazon.com/AmazonS3/latest/userguide/checking-object-integrity.html
+
+	let must_recopy = !EncryptionParams::is_same(&source_encryption, &dest_encryption)
+		|| source_checksum_algorithm != checksum_algorithm
+		|| (was_multipart && checksum_algorithm.is_some());
+
+	let res = if !must_recopy {
+		// In most cases, we can just copy the metadata and link blocks of the
 		// old object from the new object.
 		handle_copy_metaonly(
 			ctx,
 			dest_key,
-			dest_object_headers,
+			dest_object_meta,
 			dest_encryption,
 			source_version,
 			source_version_data,
@@ -80,16 +113,27 @@ pub async fn handle_copy(
 		)
 		.await?
 	} else {
+		let expected_checksum = ExpectedChecksums {
+			md5: None,
+			sha256: None,
+			extra: source_checksum,
+		};
+		let checksum_mode = if was_multipart || source_checksum_algorithm != checksum_algorithm {
+			ChecksumMode::Calculate(checksum_algorithm)
+		} else {
+			ChecksumMode::Verify(&expected_checksum)
+		};
 		// If source and dest encryption use different keys,
 		// we must decrypt content and re-encrypt, so rewrite all data blocks.
 		handle_copy_reencrypt(
 			ctx,
 			dest_key,
-			dest_object_headers,
+			dest_object_meta,
 			dest_encryption,
 			source_version,
 			source_version_data,
 			source_encryption,
+			checksum_mode,
 		)
 		.await?
 	};
@@ -115,7 +159,7 @@ pub async fn handle_copy(
 async fn handle_copy_metaonly(
 	ctx: ReqCtx,
 	dest_key: &str,
-	dest_object_headers: ObjectVersionHeaders,
+	dest_object_meta: ObjectVersionMetaInner,
 	dest_encryption: EncryptionParams,
 	source_version: &ObjectVersion,
 	source_version_data: &ObjectVersionData,
@@ -132,7 +176,7 @@ async fn handle_copy_metaonly(
 	let new_timestamp = now_msec();
 
 	let new_meta = ObjectVersionMeta {
-		encryption: dest_encryption.encrypt_headers(dest_object_headers)?,
+		encryption: dest_encryption.encrypt_meta(dest_object_meta)?,
 		size: source_version_meta.size,
 		etag: source_version_meta.etag.clone(),
 	};
@@ -180,6 +224,7 @@ async fn handle_copy_metaonly(
 				timestamp: new_timestamp,
 				state: ObjectVersionState::Uploading {
 					encryption: new_meta.encryption.clone(),
+					checksum_algorithm: None,
 					multipart: false,
 				},
 			};
@@ -252,11 +297,12 @@ async fn handle_copy_metaonly(
 async fn handle_copy_reencrypt(
 	ctx: ReqCtx,
 	dest_key: &str,
-	dest_object_headers: ObjectVersionHeaders,
+	dest_object_meta: ObjectVersionMetaInner,
 	dest_encryption: EncryptionParams,
 	source_version: &ObjectVersion,
 	source_version_data: &ObjectVersionData,
 	source_encryption: EncryptionParams,
+	checksum_mode: ChecksumMode<'_>,
 ) -> Result<SaveStreamResult, Error> {
 	// basically we will read the source data (decrypt if necessary)
 	// and save that in a new object (encrypt if necessary),
@@ -270,12 +316,11 @@ async fn handle_copy_reencrypt(
 
 	save_stream(
 		&ctx,
-		dest_object_headers,
+		dest_object_meta,
 		dest_encryption,
 		source_stream.map_err(|e| Error::from(GarageError::from(e))),
 		&dest_key.to_string(),
-		None,
-		None,
+		checksum_mode,
 	)
 	.await
 }
@@ -313,8 +358,12 @@ pub async fn handle_upload_part_copy(
 		req.headers(),
 		&source_version_meta.encryption,
 	)?;
-	let dest_object_encryption = match dest_version.state {
-		ObjectVersionState::Uploading { encryption, .. } => encryption,
+	let (dest_object_encryption, dest_object_checksum_algorithm) = match dest_version.state {
+		ObjectVersionState::Uploading {
+			encryption,
+			checksum_algorithm,
+			..
+		} => (encryption, checksum_algorithm),
 		_ => unreachable!(),
 	};
 	let (dest_encryption, _) =
@@ -412,7 +461,9 @@ pub async fn handle_upload_part_copy(
 		dest_mpu_part_key,
 		MpuPart {
 			version: dest_version_id,
+			// These are all filled in later (bottom of this function)
 			etag: None,
+			checksum: None,
 			size: None,
 		},
 	);
@@ -429,7 +480,8 @@ pub async fn handle_upload_part_copy(
 	garage.version_table.insert(&dest_version).await?;
 
 	// Now, actually copy the blocks
-	let mut md5hasher = Md5::new();
+	let mut checksummer = Checksummer::init(&Default::default(), !dest_encryption.is_encrypted())
+		.add(dest_object_checksum_algorithm);
 
 	// First, create a stream that is able to read the source blocks
 	// and extract the subrange if necessary.
@@ -495,18 +547,24 @@ pub async fn handle_upload_part_copy(
 		}
 
 		let data_len = data.len() as u64;
-		md5hasher.update(&data[..]);
-
-		let (final_data, must_upload, final_hash) = match existing_block_hash {
-			Some(hash) if same_encryption => (data, false, hash),
-			_ => tokio::task::spawn_blocking(move || {
-				let data_enc = dest_encryption.encrypt_block(data)?;
-				let hash = blake2sum(&data_enc);
-				Ok::<_, Error>((data_enc, true, hash))
+
+		let (checksummer_updated, (data_to_upload, final_hash)) =
+			tokio::task::spawn_blocking(move || {
+				checksummer.update(&data[..]);
+
+				let tup = match existing_block_hash {
+					Some(hash) if same_encryption => (None, hash),
+					_ => {
+						let data_enc = dest_encryption.encrypt_block(data)?;
+						let hash = blake2sum(&data_enc);
+						(Some(data_enc), hash)
+					}
+				};
+				Ok::<_, Error>((checksummer, tup))
 			})
 			.await
-			.unwrap()?,
-		};
+			.unwrap()?;
+		checksummer = checksummer_updated;
 
 		dest_version.blocks.clear();
 		dest_version.blocks.put(
@@ -531,7 +589,7 @@ pub async fn handle_upload_part_copy(
 			// Thing 1: if the block is not exactly a block that existed before,
 			// we need to insert that data as a new block.
 			async {
-				if must_upload {
+				if let Some(final_data) = data_to_upload {
 					garage
 						.block_manager
 						.rpc_put_block(final_hash, final_data, dest_encryption.is_encrypted(), None)
@@ -552,8 +610,9 @@ pub async fn handle_upload_part_copy(
 
 	assert_eq!(current_offset, source_range.length);
 
-	let data_md5sum = md5hasher.finalize();
-	let etag = dest_encryption.etag_from_md5(&data_md5sum);
+	let checksums = checksummer.finalize();
+	let etag = dest_encryption.etag_from_md5(&checksums.md5);
+	let checksum = checksums.extract(dest_object_checksum_algorithm);
 
 	// Put the part's ETag in the Versiontable
 	dest_mpu.parts.put(
@@ -561,6 +620,7 @@ pub async fn handle_upload_part_copy(
 		MpuPart {
 			version: dest_version_id,
 			etag: Some(etag.clone()),
+			checksum,
 			size: Some(current_offset),
 		},
 	);
diff --git a/src/api/s3/encryption.rs b/src/api/s3/encryption.rs
index 2b105e90..2e6ed65c 100644
--- a/src/api/s3/encryption.rs
+++ b/src/api/s3/encryption.rs
@@ -26,9 +26,10 @@ use garage_util::error::Error as GarageError;
 use garage_util::migrate::Migrate;
 
 use garage_model::garage::Garage;
-use garage_model::s3::object_table::{ObjectVersionEncryption, ObjectVersionHeaders};
+use garage_model::s3::object_table::{ObjectVersionEncryption, ObjectVersionMetaInner};
 
 use crate::common_error::*;
+use crate::s3::checksum::Md5Checksum;
 use crate::s3::error::Error;
 
 const X_AMZ_SERVER_SIDE_ENCRYPTION_CUSTOMER_ALGORITHM: HeaderName =
@@ -124,7 +125,7 @@ impl EncryptionParams {
 		garage: &Garage,
 		headers: &HeaderMap,
 		obj_enc: &'a ObjectVersionEncryption,
-	) -> Result<(Self, Cow<'a, ObjectVersionHeaders>), Error> {
+	) -> Result<(Self, Cow<'a, ObjectVersionMetaInner>), Error> {
 		let key = parse_request_headers(
 			headers,
 			&X_AMZ_SERVER_SIDE_ENCRYPTION_CUSTOMER_ALGORITHM,
@@ -138,7 +139,7 @@ impl EncryptionParams {
 		garage: &Garage,
 		headers: &HeaderMap,
 		obj_enc: &'a ObjectVersionEncryption,
-	) -> Result<(Self, Cow<'a, ObjectVersionHeaders>), Error> {
+	) -> Result<(Self, Cow<'a, ObjectVersionMetaInner>), Error> {
 		let key = parse_request_headers(
 			headers,
 			&X_AMZ_COPY_SOURCE_SERVER_SIDE_ENCRYPTION_CUSTOMER_ALGORITHM,
@@ -152,14 +153,11 @@ impl EncryptionParams {
 		garage: &Garage,
 		key: Option<(Key<Aes256Gcm>, Md5Output)>,
 		obj_enc: &'a ObjectVersionEncryption,
-	) -> Result<(Self, Cow<'a, ObjectVersionHeaders>), Error> {
+	) -> Result<(Self, Cow<'a, ObjectVersionMetaInner>), Error> {
 		match (key, &obj_enc) {
 			(
 				Some((client_key, client_key_md5)),
-				ObjectVersionEncryption::SseC {
-					headers,
-					compressed,
-				},
+				ObjectVersionEncryption::SseC { inner, compressed },
 			) => {
 				let enc = Self::SseC {
 					client_key,
@@ -170,13 +168,13 @@ impl EncryptionParams {
 						None
 					},
 				};
-				let plaintext = enc.decrypt_blob(&headers)?;
-				let headers = ObjectVersionHeaders::decode(&plaintext)
-					.ok_or_internal_error("Could not decode encrypted headers")?;
-				Ok((enc, Cow::Owned(headers)))
+				let plaintext = enc.decrypt_blob(&inner)?;
+				let inner = ObjectVersionMetaInner::decode(&plaintext)
+					.ok_or_internal_error("Could not decode encrypted metadata")?;
+				Ok((enc, Cow::Owned(inner)))
 			}
-			(None, ObjectVersionEncryption::Plaintext { headers }) => {
-				Ok((Self::Plaintext, Cow::Borrowed(headers)))
+			(None, ObjectVersionEncryption::Plaintext { inner }) => {
+				Ok((Self::Plaintext, Cow::Borrowed(inner)))
 			}
 			(_, ObjectVersionEncryption::SseC { .. }) => {
 				Err(Error::bad_request("Object is encrypted"))
@@ -188,29 +186,31 @@ impl EncryptionParams {
 		}
 	}
 
-	pub fn encrypt_headers(
+	pub fn encrypt_meta(
 		&self,
-		h: ObjectVersionHeaders,
+		meta: ObjectVersionMetaInner,
 	) -> Result<ObjectVersionEncryption, Error> {
 		match self {
 			Self::SseC {
 				compression_level, ..
 			} => {
-				let plaintext = h.encode().map_err(GarageError::from)?;
+				let plaintext = meta.encode().map_err(GarageError::from)?;
 				let ciphertext = self.encrypt_blob(&plaintext)?;
 				Ok(ObjectVersionEncryption::SseC {
-					headers: ciphertext.into_owned(),
+					inner: ciphertext.into_owned(),
 					compressed: compression_level.is_some(),
 				})
 			}
-			Self::Plaintext => Ok(ObjectVersionEncryption::Plaintext { headers: h }),
+			Self::Plaintext => Ok(ObjectVersionEncryption::Plaintext { inner: meta }),
 		}
 	}
 
 	// ---- generating object Etag values ----
-	pub fn etag_from_md5(&self, md5sum: &[u8]) -> String {
+	pub fn etag_from_md5(&self, md5sum: &Option<Md5Checksum>) -> String {
 		match self {
-			Self::Plaintext => hex::encode(md5sum),
+			Self::Plaintext => md5sum
+				.map(|x| hex::encode(&x[..]))
+				.expect("md5 digest should have been computed"),
 			Self::SseC { .. } => {
 				// AWS specifies that for encrypted objects, the Etag is not
 				// the md5sum of the data, but doesn't say what it is.
@@ -224,7 +224,7 @@ impl EncryptionParams {
 
 	// ---- generic function for encrypting / decrypting blobs ----
 	// Prepends a randomly-generated nonce to the encrypted value.
-	// This is used for encrypting object headers and inlined data for small objects.
+	// This is used for encrypting object metadata and inlined data for small objects.
 	// This does not compress anything.
 
 	pub fn encrypt_blob<'a>(&self, blob: &'a [u8]) -> Result<Cow<'a, [u8]>, Error> {
diff --git a/src/api/s3/error.rs b/src/api/s3/error.rs
index 5cb5d04e..2855e0b3 100644
--- a/src/api/s3/error.rs
+++ b/src/api/s3/error.rs
@@ -69,6 +69,10 @@ pub enum Error {
 	#[error(display = "Invalid encryption algorithm: {:?}, should be AES256", _0)]
 	InvalidEncryptionAlgorithm(String),
 
+	/// The client sent invalid XML data
+	#[error(display = "Invalid digest: {}", _0)]
+	InvalidDigest(String),
+
 	/// The client sent a request for an action not supported by garage
 	#[error(display = "Unimplemented action: {}", _0)]
 	NotImplemented(String),
@@ -129,6 +133,7 @@ impl Error {
 			Error::NotImplemented(_) => "NotImplemented",
 			Error::InvalidXml(_) => "MalformedXML",
 			Error::InvalidRange(_) => "InvalidRange",
+			Error::InvalidDigest(_) => "InvalidDigest",
 			Error::InvalidUtf8Str(_) | Error::InvalidUtf8String(_) => "InvalidRequest",
 			Error::InvalidEncryptionAlgorithm(_) => "InvalidEncryptionAlgorithmError",
 		}
@@ -148,6 +153,7 @@ impl ApiError for Error {
 			| Error::InvalidPart
 			| Error::InvalidPartOrder
 			| Error::EntityTooSmall
+			| Error::InvalidDigest(_)
 			| Error::InvalidEncryptionAlgorithm(_)
 			| Error::InvalidXml(_)
 			| Error::InvalidUtf8Str(_)
diff --git a/src/api/s3/get.rs b/src/api/s3/get.rs
index ec300ab7..f5d3cf11 100644
--- a/src/api/s3/get.rs
+++ b/src/api/s3/get.rs
@@ -27,6 +27,7 @@ use garage_model::s3::version_table::*;
 
 use crate::helpers::*;
 use crate::s3::api_server::ResBody;
+use crate::s3::checksum::{add_checksum_response_headers, X_AMZ_CHECKSUM_MODE};
 use crate::s3::encryption::EncryptionParams;
 use crate::s3::error::*;
 
@@ -45,8 +46,9 @@ pub struct GetObjectOverrides {
 fn object_headers(
 	version: &ObjectVersion,
 	version_meta: &ObjectVersionMeta,
-	headers: &ObjectVersionHeaders,
+	meta_inner: &ObjectVersionMetaInner,
 	encryption: EncryptionParams,
+	checksum_mode: ChecksumMode,
 ) -> http::response::Builder {
 	debug!("Version meta: {:?}", version_meta);
 
@@ -65,7 +67,7 @@ fn object_headers(
 	// have the same name (ignoring case) into a comma-delimited list.
 	// See: https://docs.aws.amazon.com/AmazonS3/latest/userguide/UsingMetadata.html
 	let mut headers_by_name = BTreeMap::new();
-	for (name, value) in headers.0.iter() {
+	for (name, value) in meta_inner.headers.iter() {
 		match headers_by_name.get_mut(name) {
 			None => {
 				headers_by_name.insert(name, vec![value.as_str()]);
@@ -80,6 +82,10 @@ fn object_headers(
 		resp = resp.header(name, values.join(","));
 	}
 
+	if checksum_mode.enabled {
+		resp = add_checksum_response_headers(&meta_inner.checksum, resp);
+	}
+
 	encryption.add_response_headers(&mut resp);
 
 	resp
@@ -199,6 +205,8 @@ pub async fn handle_head_without_ctx(
 	let (encryption, headers) =
 		EncryptionParams::check_decrypt(&garage, req.headers(), &version_meta.encryption)?;
 
+	let checksum_mode = checksum_mode(&req);
+
 	if let Some(pn) = part_number {
 		match version_data {
 			ObjectVersionData::Inline(_, _) => {
@@ -206,17 +214,21 @@ pub async fn handle_head_without_ctx(
 					return Err(Error::InvalidPart);
 				}
 				let bytes_len = version_meta.size;
-				Ok(
-					object_headers(object_version, version_meta, &headers, encryption)
-						.header(CONTENT_LENGTH, format!("{}", bytes_len))
-						.header(
-							CONTENT_RANGE,
-							format!("bytes 0-{}/{}", bytes_len - 1, bytes_len),
-						)
-						.header(X_AMZ_MP_PARTS_COUNT, "1")
-						.status(StatusCode::PARTIAL_CONTENT)
-						.body(empty_body())?,
+				Ok(object_headers(
+					object_version,
+					version_meta,
+					&headers,
+					encryption,
+					checksum_mode,
+				)
+				.header(CONTENT_LENGTH, format!("{}", bytes_len))
+				.header(
+					CONTENT_RANGE,
+					format!("bytes 0-{}/{}", bytes_len - 1, bytes_len),
 				)
+				.header(X_AMZ_MP_PARTS_COUNT, "1")
+				.status(StatusCode::PARTIAL_CONTENT)
+				.body(empty_body())?)
 			}
 			ObjectVersionData::FirstBlock(_, _) => {
 				let version = garage
@@ -228,32 +240,40 @@ pub async fn handle_head_without_ctx(
 				let (part_offset, part_end) =
 					calculate_part_bounds(&version, pn).ok_or(Error::InvalidPart)?;
 
-				Ok(
-					object_headers(object_version, version_meta, &headers, encryption)
-						.header(CONTENT_LENGTH, format!("{}", part_end - part_offset))
-						.header(
-							CONTENT_RANGE,
-							format!(
-								"bytes {}-{}/{}",
-								part_offset,
-								part_end - 1,
-								version_meta.size
-							),
-						)
-						.header(X_AMZ_MP_PARTS_COUNT, format!("{}", version.n_parts()?))
-						.status(StatusCode::PARTIAL_CONTENT)
-						.body(empty_body())?,
+				Ok(object_headers(
+					object_version,
+					version_meta,
+					&headers,
+					encryption,
+					checksum_mode,
 				)
+				.header(CONTENT_LENGTH, format!("{}", part_end - part_offset))
+				.header(
+					CONTENT_RANGE,
+					format!(
+						"bytes {}-{}/{}",
+						part_offset,
+						part_end - 1,
+						version_meta.size
+					),
+				)
+				.header(X_AMZ_MP_PARTS_COUNT, format!("{}", version.n_parts()?))
+				.status(StatusCode::PARTIAL_CONTENT)
+				.body(empty_body())?)
 			}
 			_ => unreachable!(),
 		}
 	} else {
-		Ok(
-			object_headers(object_version, version_meta, &headers, encryption)
-				.header(CONTENT_LENGTH, format!("{}", version_meta.size))
-				.status(StatusCode::OK)
-				.body(empty_body())?,
+		Ok(object_headers(
+			object_version,
+			version_meta,
+			&headers,
+			encryption,
+			checksum_mode,
 		)
+		.header(CONTENT_LENGTH, format!("{}", version_meta.size))
+		.status(StatusCode::OK)
+		.body(empty_body())?)
 	}
 }
 
@@ -307,12 +327,24 @@ pub async fn handle_get_without_ctx(
 	let (enc, headers) =
 		EncryptionParams::check_decrypt(&garage, req.headers(), &last_v_meta.encryption)?;
 
+	let checksum_mode = checksum_mode(&req);
+
 	match (part_number, parse_range_header(req, last_v_meta.size)?) {
 		(Some(_), Some(_)) => Err(Error::bad_request(
 			"Cannot specify both partNumber and Range header",
 		)),
 		(Some(pn), None) => {
-			handle_get_part(garage, last_v, last_v_data, last_v_meta, enc, &headers, pn).await
+			handle_get_part(
+				garage,
+				last_v,
+				last_v_data,
+				last_v_meta,
+				enc,
+				&headers,
+				pn,
+				checksum_mode,
+			)
+			.await
 		}
 		(None, Some(range)) => {
 			handle_get_range(
@@ -324,6 +356,7 @@ pub async fn handle_get_without_ctx(
 				&headers,
 				range.start,
 				range.start + range.length,
+				checksum_mode,
 			)
 			.await
 		}
@@ -336,6 +369,7 @@ pub async fn handle_get_without_ctx(
 				enc,
 				&headers,
 				overrides,
+				checksum_mode,
 			)
 			.await
 		}
@@ -348,12 +382,19 @@ async fn handle_get_full(
 	version_data: &ObjectVersionData,
 	version_meta: &ObjectVersionMeta,
 	encryption: EncryptionParams,
-	headers: &ObjectVersionHeaders,
+	meta_inner: &ObjectVersionMetaInner,
 	overrides: GetObjectOverrides,
+	checksum_mode: ChecksumMode,
 ) -> Result<Response<ResBody>, Error> {
-	let mut resp_builder = object_headers(version, version_meta, &headers, encryption)
-		.header(CONTENT_LENGTH, format!("{}", version_meta.size))
-		.status(StatusCode::OK);
+	let mut resp_builder = object_headers(
+		version,
+		version_meta,
+		&meta_inner,
+		encryption,
+		checksum_mode,
+	)
+	.header(CONTENT_LENGTH, format!("{}", version_meta.size))
+	.status(StatusCode::OK);
 	getobject_override_headers(overrides, &mut resp_builder)?;
 
 	let stream = full_object_byte_stream(garage, version, version_data, encryption);
@@ -432,14 +473,15 @@ async fn handle_get_range(
 	version_data: &ObjectVersionData,
 	version_meta: &ObjectVersionMeta,
 	encryption: EncryptionParams,
-	headers: &ObjectVersionHeaders,
+	meta_inner: &ObjectVersionMetaInner,
 	begin: u64,
 	end: u64,
+	checksum_mode: ChecksumMode,
 ) -> Result<Response<ResBody>, Error> {
 	// Here we do not use getobject_override_headers because we don't
 	// want to add any overridden headers (those should not be added
 	// when returning PARTIAL_CONTENT)
-	let resp_builder = object_headers(version, version_meta, headers, encryption)
+	let resp_builder = object_headers(version, version_meta, meta_inner, encryption, checksum_mode)
 		.header(CONTENT_LENGTH, format!("{}", end - begin))
 		.header(
 			CONTENT_RANGE,
@@ -480,12 +522,19 @@ async fn handle_get_part(
 	version_data: &ObjectVersionData,
 	version_meta: &ObjectVersionMeta,
 	encryption: EncryptionParams,
-	headers: &ObjectVersionHeaders,
+	meta_inner: &ObjectVersionMetaInner,
 	part_number: u64,
+	checksum_mode: ChecksumMode,
 ) -> Result<Response<ResBody>, Error> {
 	// Same as for get_range, no getobject_override_headers
-	let resp_builder = object_headers(object_version, version_meta, headers, encryption)
-		.status(StatusCode::PARTIAL_CONTENT);
+	let resp_builder = object_headers(
+		object_version,
+		version_meta,
+		meta_inner,
+		encryption,
+		checksum_mode,
+	)
+	.status(StatusCode::PARTIAL_CONTENT);
 
 	match version_data {
 		ObjectVersionData::Inline(_, bytes) => {
@@ -567,6 +616,20 @@ fn calculate_part_bounds(v: &Version, part_number: u64) -> Option<(u64, u64)> {
 	None
 }
 
+struct ChecksumMode {
+	enabled: bool,
+}
+
+fn checksum_mode(req: &Request<impl Body>) -> ChecksumMode {
+	ChecksumMode {
+		enabled: req
+			.headers()
+			.get(X_AMZ_CHECKSUM_MODE)
+			.map(|x| x == "ENABLED")
+			.unwrap_or(false),
+	}
+}
+
 fn body_from_blocks_range(
 	garage: Arc<Garage>,
 	encryption: EncryptionParams,
diff --git a/src/api/s3/list.rs b/src/api/s3/list.rs
index 1678f1fa..648bace2 100644
--- a/src/api/s3/list.rs
+++ b/src/api/s3/list.rs
@@ -2,7 +2,7 @@ use std::collections::{BTreeMap, BTreeSet};
 use std::iter::{Iterator, Peekable};
 
 use base64::prelude::*;
-use hyper::Response;
+use hyper::{Request, Response};
 
 use garage_util::data::*;
 use garage_util::error::Error as GarageError;
@@ -15,7 +15,8 @@ use garage_table::EnumerationOrder;
 
 use crate::encoding::*;
 use crate::helpers::*;
-use crate::s3::api_server::ResBody;
+use crate::s3::api_server::{ReqBody, ResBody};
+use crate::s3::encryption::EncryptionParams;
 use crate::s3::error::*;
 use crate::s3::multipart as s3_multipart;
 use crate::s3::xml as s3_xml;
@@ -271,13 +272,21 @@ pub async fn handle_list_multipart_upload(
 
 pub async fn handle_list_parts(
 	ctx: ReqCtx,
+	req: Request<ReqBody>,
 	query: &ListPartsQuery,
 ) -> Result<Response<ResBody>, Error> {
 	debug!("ListParts {:?}", query);
 
 	let upload_id = s3_multipart::decode_upload_id(&query.upload_id)?;
 
-	let (_, _, mpu) = s3_multipart::get_upload(&ctx, &query.key, &upload_id).await?;
+	let (_, object_version, mpu) = s3_multipart::get_upload(&ctx, &query.key, &upload_id).await?;
+
+	let object_encryption = match object_version.state {
+		ObjectVersionState::Uploading { encryption, .. } => encryption,
+		_ => unreachable!(),
+	};
+	let encryption_res =
+		EncryptionParams::check_decrypt(&ctx.garage, req.headers(), &object_encryption);
 
 	let (info, next) = fetch_part_info(query, &mpu)?;
 
@@ -296,11 +305,40 @@ pub async fn handle_list_parts(
 		is_truncated: s3_xml::Value(format!("{}", next.is_some())),
 		parts: info
 			.iter()
-			.map(|part| s3_xml::PartItem {
-				etag: s3_xml::Value(format!("\"{}\"", part.etag)),
-				last_modified: s3_xml::Value(msec_to_rfc3339(part.timestamp)),
-				part_number: s3_xml::IntValue(part.part_number as i64),
-				size: s3_xml::IntValue(part.size as i64),
+			.map(|part| {
+				// hide checksum if object is encrypted and the decryption
+				// keys are not provided
+				let checksum = part.checksum.filter(|_| encryption_res.is_ok());
+				s3_xml::PartItem {
+					etag: s3_xml::Value(format!("\"{}\"", part.etag)),
+					last_modified: s3_xml::Value(msec_to_rfc3339(part.timestamp)),
+					part_number: s3_xml::IntValue(part.part_number as i64),
+					size: s3_xml::IntValue(part.size as i64),
+					checksum_crc32: match &checksum {
+						Some(ChecksumValue::Crc32(x)) => {
+							Some(s3_xml::Value(BASE64_STANDARD.encode(&x)))
+						}
+						_ => None,
+					},
+					checksum_crc32c: match &checksum {
+						Some(ChecksumValue::Crc32c(x)) => {
+							Some(s3_xml::Value(BASE64_STANDARD.encode(&x)))
+						}
+						_ => None,
+					},
+					checksum_sha1: match &checksum {
+						Some(ChecksumValue::Sha1(x)) => {
+							Some(s3_xml::Value(BASE64_STANDARD.encode(&x)))
+						}
+						_ => None,
+					},
+					checksum_sha256: match &checksum {
+						Some(ChecksumValue::Sha256(x)) => {
+							Some(s3_xml::Value(BASE64_STANDARD.encode(&x)))
+						}
+						_ => None,
+					},
+				}
 			})
 			.collect(),
 
@@ -346,6 +384,7 @@ struct PartInfo<'a> {
 	timestamp: u64,
 	part_number: u64,
 	size: u64,
+	checksum: Option<ChecksumValue>,
 }
 
 enum ExtractionResult {
@@ -486,6 +525,7 @@ fn fetch_part_info<'a>(
 				timestamp: pk.timestamp,
 				etag,
 				size,
+				checksum: p.checksum,
 			};
 			match parts.last_mut() {
 				Some(lastpart) if lastpart.part_number == pk.part_number => {
@@ -945,8 +985,12 @@ mod tests {
 			state: ObjectVersionState::Uploading {
 				multipart: true,
 				encryption: ObjectVersionEncryption::Plaintext {
-					headers: ObjectVersionHeaders(vec![]),
+					inner: ObjectVersionMetaInner {
+						headers: vec![],
+						checksum: None,
+					},
 				},
+				checksum_algorithm: None,
 			},
 		}
 	}
@@ -1135,6 +1179,7 @@ mod tests {
 					version: uuid,
 					size: Some(3),
 					etag: Some("etag1".into()),
+					checksum: None,
 				},
 			),
 			(
@@ -1146,6 +1191,7 @@ mod tests {
 					version: uuid,
 					size: None,
 					etag: None,
+					checksum: None,
 				},
 			),
 			(
@@ -1157,6 +1203,7 @@ mod tests {
 					version: uuid,
 					size: Some(10),
 					etag: Some("etag2".into()),
+					checksum: None,
 				},
 			),
 			(
@@ -1168,6 +1215,7 @@ mod tests {
 					version: uuid,
 					size: Some(7),
 					etag: Some("etag3".into()),
+					checksum: None,
 				},
 			),
 			(
@@ -1179,6 +1227,7 @@ mod tests {
 					version: uuid,
 					size: Some(5),
 					etag: Some("etag4".into()),
+					checksum: None,
 				},
 			),
 		];
@@ -1217,12 +1266,14 @@ mod tests {
 					etag: "etag1",
 					timestamp: TS,
 					part_number: 1,
-					size: 3
+					size: 3,
+					checksum: None,
 				},
 				PartInfo {
 					etag: "etag2",
 					timestamp: TS,
 					part_number: 3,
+					checksum: None,
 					size: 10
 				},
 			]
@@ -1238,12 +1289,14 @@ mod tests {
 				PartInfo {
 					etag: "etag3",
 					timestamp: TS,
+					checksum: None,
 					part_number: 5,
 					size: 7
 				},
 				PartInfo {
 					etag: "etag4",
 					timestamp: TS,
+					checksum: None,
 					part_number: 8,
 					size: 5
 				},
@@ -1267,24 +1320,28 @@ mod tests {
 				PartInfo {
 					etag: "etag1",
 					timestamp: TS,
+					checksum: None,
 					part_number: 1,
 					size: 3
 				},
 				PartInfo {
 					etag: "etag2",
 					timestamp: TS,
+					checksum: None,
 					part_number: 3,
 					size: 10
 				},
 				PartInfo {
 					etag: "etag3",
 					timestamp: TS,
+					checksum: None,
 					part_number: 5,
 					size: 7
 				},
 				PartInfo {
 					etag: "etag4",
 					timestamp: TS,
+					checksum: None,
 					part_number: 8,
 					size: 5
 				},
diff --git a/src/api/s3/mod.rs b/src/api/s3/mod.rs
index 1eb95d40..b9bb1a6f 100644
--- a/src/api/s3/mod.rs
+++ b/src/api/s3/mod.rs
@@ -13,6 +13,7 @@ mod post_object;
 mod put;
 mod website;
 
+mod checksum;
 mod encryption;
 mod router;
 pub mod xml;
diff --git a/src/api/s3/multipart.rs b/src/api/s3/multipart.rs
index fcc5769f..3db3e8aa 100644
--- a/src/api/s3/multipart.rs
+++ b/src/api/s3/multipart.rs
@@ -1,9 +1,10 @@
 use std::collections::HashMap;
+use std::convert::TryInto;
 use std::sync::Arc;
 
+use base64::prelude::*;
 use futures::prelude::*;
 use hyper::{Request, Response};
-use md5::{Digest as Md5Digest, Md5};
 
 use garage_table::*;
 use garage_util::data::*;
@@ -16,6 +17,7 @@ use garage_model::s3::version_table::*;
 
 use crate::helpers::*;
 use crate::s3::api_server::{ReqBody, ResBody};
+use crate::s3::checksum::*;
 use crate::s3::encryption::EncryptionParams;
 use crate::s3::error::*;
 use crate::s3::put::*;
@@ -41,10 +43,16 @@ pub async fn handle_create_multipart_upload(
 	let timestamp = next_timestamp(existing_object.as_ref());
 
 	let headers = get_headers(req.headers())?;
+	let meta = ObjectVersionMetaInner {
+		headers,
+		checksum: None,
+	};
 
 	// Determine whether object should be encrypted, and if so the key
 	let encryption = EncryptionParams::new_from_headers(&garage, req.headers())?;
-	let object_encryption = encryption.encrypt_headers(headers)?;
+	let object_encryption = encryption.encrypt_meta(meta)?;
+
+	let checksum_algorithm = request_checksum_algorithm(req.headers())?;
 
 	// Create object in object table
 	let object_version = ObjectVersion {
@@ -53,6 +61,7 @@ pub async fn handle_create_multipart_upload(
 		state: ObjectVersionState::Uploading {
 			multipart: true,
 			encryption: object_encryption,
+			checksum_algorithm,
 		},
 	};
 	let object = Object::new(*bucket_id, key.to_string(), vec![object_version]);
@@ -90,9 +99,13 @@ pub async fn handle_put_part(
 
 	let upload_id = decode_upload_id(upload_id)?;
 
-	let content_md5 = match req.headers().get("content-md5") {
-		Some(x) => Some(x.to_str()?.to_string()),
-		None => None,
+	let expected_checksums = ExpectedChecksums {
+		md5: match req.headers().get("content-md5") {
+			Some(x) => Some(x.to_str()?.to_string()),
+			None => None,
+		},
+		sha256: content_sha256,
+		extra: request_checksum_value(req.headers())?,
 	};
 
 	// Read first chuck, and at the same time try to get object to see if it exists
@@ -106,8 +119,12 @@ pub async fn handle_put_part(
 		futures::try_join!(get_upload(&ctx, &key, &upload_id), chunker.next(),)?;
 
 	// Check encryption params
-	let object_encryption = match object_version.state {
-		ObjectVersionState::Uploading { encryption, .. } => encryption,
+	let (object_encryption, checksum_algorithm) = match object_version.state {
+		ObjectVersionState::Uploading {
+			encryption,
+			checksum_algorithm,
+			..
+		} => (encryption, checksum_algorithm),
 		_ => unreachable!(),
 	};
 	let (encryption, _) =
@@ -138,7 +155,9 @@ pub async fn handle_put_part(
 		mpu_part_key,
 		MpuPart {
 			version: version_uuid,
+			// all these are filled in later, at the end of this function
 			etag: None,
+			checksum: None,
 			size: None,
 		},
 	);
@@ -152,32 +171,31 @@ pub async fn handle_put_part(
 	garage.version_table.insert(&version).await?;
 
 	// Copy data to version
-	let (total_size, data_md5sum, data_sha256sum, _) = read_and_put_blocks(
+	let checksummer =
+		Checksummer::init(&expected_checksums, !encryption.is_encrypted()).add(checksum_algorithm);
+	let (total_size, checksums, _) = read_and_put_blocks(
 		&ctx,
 		&version,
 		encryption,
 		part_number,
 		first_block,
 		&mut chunker,
+		checksummer,
 	)
 	.await?;
 
 	// Verify that checksums map
-	ensure_checksum_matches(
-		&data_md5sum,
-		data_sha256sum,
-		content_md5.as_deref(),
-		content_sha256,
-	)?;
+	checksums.verify(&expected_checksums)?;
 
 	// Store part etag in version
-	let etag = encryption.etag_from_md5(&data_md5sum);
+	let etag = encryption.etag_from_md5(&checksums.md5);
 
 	mpu.parts.put(
 		mpu_part_key,
 		MpuPart {
 			version: version_uuid,
 			etag: Some(etag.clone()),
+			checksum: checksums.extract(checksum_algorithm),
 			size: Some(total_size),
 		},
 	);
@@ -189,6 +207,7 @@ pub async fn handle_put_part(
 
 	let mut resp = Response::builder().header("ETag", format!("\"{}\"", etag));
 	encryption.add_response_headers(&mut resp);
+	let resp = add_checksum_response_headers(&expected_checksums.extra, resp);
 	Ok(resp.body(empty_body())?)
 }
 
@@ -236,10 +255,11 @@ pub async fn handle_complete_multipart_upload(
 		bucket_name,
 		..
 	} = &ctx;
+	let (req_head, req_body) = req.into_parts();
 
-	let body = http_body_util::BodyExt::collect(req.into_body())
-		.await?
-		.to_bytes();
+	let expected_checksum = request_checksum_value(&req_head.headers)?;
+
+	let body = http_body_util::BodyExt::collect(req_body).await?.to_bytes();
 
 	if let Some(content_sha256) = content_sha256 {
 		verify_signed_content(content_sha256, &body[..])?;
@@ -263,8 +283,12 @@ pub async fn handle_complete_multipart_upload(
 		return Err(Error::bad_request("No data was uploaded"));
 	}
 
-	let object_encryption = match object_version.state {
-		ObjectVersionState::Uploading { encryption, .. } => encryption,
+	let (object_encryption, checksum_algorithm) = match object_version.state {
+		ObjectVersionState::Uploading {
+			encryption,
+			checksum_algorithm,
+			..
+		} => (encryption, checksum_algorithm),
 		_ => unreachable!(),
 	};
 
@@ -292,6 +316,13 @@ pub async fn handle_complete_multipart_upload(
 	for req_part in body_list_of_parts.iter() {
 		match have_parts.get(&req_part.part_number) {
 			Some(part) if part.etag.as_ref() == Some(&req_part.etag) && part.size.is_some() => {
+				// alternative version: if req_part.checksum.is_some() && part.checksum != req_part.checksum {
+				if part.checksum != req_part.checksum {
+					return Err(Error::InvalidDigest(format!(
+						"Invalid checksum for part {}: in request = {:?}, uploaded part = {:?}",
+						req_part.part_number, req_part.checksum, part.checksum
+					)));
+				}
 				parts.push(*part)
 			}
 			_ => return Err(Error::InvalidPart),
@@ -339,18 +370,23 @@ pub async fn handle_complete_multipart_upload(
 	});
 	garage.block_ref_table.insert_many(block_refs).await?;
 
-	// Calculate etag of final object
+	// Calculate checksum and etag of final object
 	// To understand how etags are calculated, read more here:
+	// https://docs.aws.amazon.com/AmazonS3/latest/userguide/checking-object-integrity.html
 	// https://teppen.io/2018/06/23/aws_s3_etags/
-	let mut etag_md5_hasher = Md5::new();
+	let mut checksummer = MultipartChecksummer::init(checksum_algorithm);
 	for part in parts.iter() {
-		etag_md5_hasher.update(part.etag.as_ref().unwrap().as_bytes());
+		checksummer.update(part.etag.as_ref().unwrap(), part.checksum)?;
+	}
+	let (checksum_md5, checksum_extra) = checksummer.finalize();
+
+	if expected_checksum.is_some() && checksum_extra != expected_checksum {
+		return Err(Error::InvalidDigest(
+			"Failed to validate x-amz-checksum-*".into(),
+		));
 	}
-	let etag = format!(
-		"{}-{}",
-		hex::encode(etag_md5_hasher.finalize()),
-		parts.len()
-	);
+
+	let etag = format!("{}-{}", hex::encode(&checksum_md5[..]), parts.len());
 
 	// Calculate total size of final object
 	let total_size = parts.iter().map(|x| x.size.unwrap()).sum();
@@ -363,6 +399,20 @@ pub async fn handle_complete_multipart_upload(
 		return Err(e);
 	}
 
+	// If there is a checksum algorithm, update metadata with checksum
+	let object_encryption = match checksum_algorithm {
+		None => object_encryption,
+		Some(_) => {
+			let (encryption, meta) =
+				EncryptionParams::check_decrypt(&garage, &req_head.headers, &object_encryption)?;
+			let new_meta = ObjectVersionMetaInner {
+				headers: meta.into_owned().headers,
+				checksum: checksum_extra,
+			};
+			encryption.encrypt_meta(new_meta)?
+		}
+	};
+
 	// Write final object version
 	object_version.state = ObjectVersionState::Complete(ObjectVersionData::FirstBlock(
 		ObjectVersionMeta {
@@ -383,10 +433,28 @@ pub async fn handle_complete_multipart_upload(
 		bucket: s3_xml::Value(bucket_name.to_string()),
 		key: s3_xml::Value(key),
 		etag: s3_xml::Value(format!("\"{}\"", etag)),
+		checksum_crc32: match &checksum_extra {
+			Some(ChecksumValue::Crc32(x)) => Some(s3_xml::Value(BASE64_STANDARD.encode(&x))),
+			_ => None,
+		},
+		checksum_crc32c: match &checksum_extra {
+			Some(ChecksumValue::Crc32c(x)) => Some(s3_xml::Value(BASE64_STANDARD.encode(&x))),
+			_ => None,
+		},
+		checksum_sha1: match &checksum_extra {
+			Some(ChecksumValue::Sha1(x)) => Some(s3_xml::Value(BASE64_STANDARD.encode(&x))),
+			_ => None,
+		},
+		checksum_sha256: match &checksum_extra {
+			Some(ChecksumValue::Sha256(x)) => Some(s3_xml::Value(BASE64_STANDARD.encode(&x))),
+			_ => None,
+		},
 	};
 	let xml = s3_xml::to_xml_with_header(&result)?;
 
-	Ok(Response::new(string_body(xml)))
+	let resp = Response::builder();
+	let resp = add_checksum_response_headers(&expected_checksum, resp);
+	Ok(resp.body(string_body(xml))?)
 }
 
 pub async fn handle_abort_multipart_upload(
@@ -455,6 +523,7 @@ pub fn decode_upload_id(id: &str) -> Result<Uuid, Error> {
 struct CompleteMultipartUploadPart {
 	etag: String,
 	part_number: u64,
+	checksum: Option<ChecksumValue>,
 }
 
 fn parse_complete_multipart_upload_body(
@@ -480,9 +549,41 @@ fn parse_complete_multipart_upload_body(
 				.children()
 				.find(|e| e.has_tag_name("PartNumber"))?
 				.text()?;
+			let checksum = if let Some(crc32) =
+				item.children().find(|e| e.has_tag_name("ChecksumCRC32"))
+			{
+				Some(ChecksumValue::Crc32(
+					BASE64_STANDARD.decode(crc32.text()?).ok()?[..]
+						.try_into()
+						.ok()?,
+				))
+			} else if let Some(crc32c) = item.children().find(|e| e.has_tag_name("ChecksumCRC32C"))
+			{
+				Some(ChecksumValue::Crc32c(
+					BASE64_STANDARD.decode(crc32c.text()?).ok()?[..]
+						.try_into()
+						.ok()?,
+				))
+			} else if let Some(sha1) = item.children().find(|e| e.has_tag_name("ChecksumSHA1")) {
+				Some(ChecksumValue::Sha1(
+					BASE64_STANDARD.decode(sha1.text()?).ok()?[..]
+						.try_into()
+						.ok()?,
+				))
+			} else if let Some(sha256) = item.children().find(|e| e.has_tag_name("ChecksumSHA256"))
+			{
+				Some(ChecksumValue::Sha256(
+					BASE64_STANDARD.decode(sha256.text()?).ok()?[..]
+						.try_into()
+						.ok()?,
+				))
+			} else {
+				None
+			};
 			parts.push(CompleteMultipartUploadPart {
 				etag: etag.trim_matches('"').to_string(),
 				part_number: part_number.parse().ok()?,
+				checksum,
 			});
 		} else {
 			return None;
diff --git a/src/api/s3/post_object.rs b/src/api/s3/post_object.rs
index 7c4219a7..2c106b3b 100644
--- a/src/api/s3/post_object.rs
+++ b/src/api/s3/post_object.rs
@@ -14,13 +14,15 @@ use multer::{Constraints, Multipart, SizeLimit};
 use serde::Deserialize;
 
 use garage_model::garage::Garage;
+use garage_model::s3::object_table::*;
 
 use crate::helpers::*;
 use crate::s3::api_server::ResBody;
+use crate::s3::checksum::*;
 use crate::s3::cors::*;
 use crate::s3::encryption::EncryptionParams;
 use crate::s3::error::*;
-use crate::s3::put::{get_headers, save_stream};
+use crate::s3::put::{get_headers, save_stream, ChecksumMode};
 use crate::s3::xml as s3_xml;
 use crate::signature::payload::{verify_v4, Authorization};
 
@@ -98,10 +100,6 @@ pub async fn handle_post_object(
 		.ok_or_bad_request("No policy was provided")?
 		.to_str()?;
 	let authorization = Authorization::parse_form(&params)?;
-	let content_md5 = params
-		.get("content-md5")
-		.map(HeaderValue::to_str)
-		.transpose()?;
 
 	let key = if key.contains("${filename}") {
 		// if no filename is provided, don't replace. This matches the behavior of AWS.
@@ -226,6 +224,21 @@ pub async fn handle_post_object(
 
 	let headers = get_headers(&params)?;
 
+	let expected_checksums = ExpectedChecksums {
+		md5: params
+			.get("content-md5")
+			.map(HeaderValue::to_str)
+			.transpose()?
+			.map(str::to_string),
+		sha256: None,
+		extra: request_checksum_algorithm_value(&params)?,
+	};
+
+	let meta = ObjectVersionMetaInner {
+		headers,
+		checksum: expected_checksums.extra,
+	};
+
 	let encryption = EncryptionParams::new_from_headers(&garage, &params)?;
 
 	let stream = file_field.map(|r| r.map_err(Into::into));
@@ -239,12 +252,11 @@ pub async fn handle_post_object(
 
 	let res = save_stream(
 		&ctx,
-		headers,
+		meta,
 		encryption,
 		StreamLimiter::new(stream, conditions.content_length),
 		&key,
-		content_md5.map(str::to_string),
-		None,
+		ChecksumMode::Verify(&expected_checksums),
 	)
 	.await?;
 
diff --git a/src/api/s3/put.rs b/src/api/s3/put.rs
index 941e4122..1e3b1b44 100644
--- a/src/api/s3/put.rs
+++ b/src/api/s3/put.rs
@@ -1,12 +1,9 @@
 use std::collections::HashMap;
 use std::sync::Arc;
 
-use base64::prelude::*;
 use futures::prelude::*;
 use futures::stream::FuturesOrdered;
 use futures::try_join;
-use md5::{digest::generic_array::*, Digest as Md5Digest, Md5};
-use sha2::Sha256;
 
 use tokio::sync::mpsc;
 
@@ -22,7 +19,6 @@ use opentelemetry::{
 use garage_net::bytes_buf::BytesBuf;
 use garage_rpc::rpc_helper::OrderTag;
 use garage_table::*;
-use garage_util::async_hash::*;
 use garage_util::data::*;
 use garage_util::error::Error as GarageError;
 use garage_util::time::*;
@@ -36,16 +32,22 @@ use garage_model::s3::version_table::*;
 
 use crate::helpers::*;
 use crate::s3::api_server::{ReqBody, ResBody};
+use crate::s3::checksum::*;
 use crate::s3::encryption::EncryptionParams;
 use crate::s3::error::*;
 
 const PUT_BLOCKS_MAX_PARALLEL: usize = 3;
 
-pub struct SaveStreamResult {
-	pub version_uuid: Uuid,
-	pub version_timestamp: u64,
+pub(crate) struct SaveStreamResult {
+	pub(crate) version_uuid: Uuid,
+	pub(crate) version_timestamp: u64,
 	/// Etag WITHOUT THE QUOTES (just the hex value)
-	pub etag: String,
+	pub(crate) etag: String,
+}
+
+pub(crate) enum ChecksumMode<'a> {
+	Verify(&'a ExpectedChecksums),
+	Calculate(Option<ChecksumAlgorithm>),
 }
 
 pub async fn handle_put(
@@ -58,24 +60,32 @@ pub async fn handle_put(
 	let headers = get_headers(req.headers())?;
 	debug!("Object headers: {:?}", headers);
 
-	// Determine whether object should be encrypted, and if so the key
-	let encryption = EncryptionParams::new_from_headers(&ctx.garage, req.headers())?;
+	let expected_checksums = ExpectedChecksums {
+		md5: match req.headers().get("content-md5") {
+			Some(x) => Some(x.to_str()?.to_string()),
+			None => None,
+		},
+		sha256: content_sha256,
+		extra: request_checksum_value(req.headers())?,
+	};
 
-	let content_md5 = match req.headers().get("content-md5") {
-		Some(x) => Some(x.to_str()?.to_string()),
-		None => None,
+	let meta = ObjectVersionMetaInner {
+		headers,
+		checksum: expected_checksums.extra,
 	};
 
+	// Determine whether object should be encrypted, and if so the key
+	let encryption = EncryptionParams::new_from_headers(&ctx.garage, req.headers())?;
+
 	let stream = body_stream(req.into_body());
 
 	let res = save_stream(
 		&ctx,
-		headers,
+		meta,
 		encryption,
 		stream,
 		key,
-		content_md5,
-		content_sha256,
+		ChecksumMode::Verify(&expected_checksums),
 	)
 	.await?;
 
@@ -83,17 +93,17 @@ pub async fn handle_put(
 		.header("x-amz-version-id", hex::encode(res.version_uuid))
 		.header("ETag", format!("\"{}\"", res.etag));
 	encryption.add_response_headers(&mut resp);
+	let resp = add_checksum_response_headers(&expected_checksums.extra, resp);
 	Ok(resp.body(empty_body())?)
 }
 
 pub(crate) async fn save_stream<S: Stream<Item = Result<Bytes, Error>> + Unpin>(
 	ctx: &ReqCtx,
-	headers: ObjectVersionHeaders,
+	mut meta: ObjectVersionMetaInner,
 	encryption: EncryptionParams,
 	body: S,
 	key: &String,
-	content_md5: Option<String>,
-	content_sha256: Option<FixedBytes32>,
+	checksum_mode: ChecksumMode<'_>,
 ) -> Result<SaveStreamResult, Error> {
 	let ReqCtx {
 		garage, bucket_id, ..
@@ -107,32 +117,36 @@ pub(crate) async fn save_stream<S: Stream<Item = Result<Bytes, Error>> + Unpin>(
 
 	let first_block = first_block_opt.unwrap_or_default();
 
-	let object_encryption = encryption.encrypt_headers(headers)?;
-
 	// Generate identity of new version
 	let version_uuid = gen_uuid();
 	let version_timestamp = next_timestamp(existing_object.as_ref());
 
+	let mut checksummer = match checksum_mode {
+		ChecksumMode::Verify(expected) => Checksummer::init(expected, !encryption.is_encrypted()),
+		ChecksumMode::Calculate(algo) => {
+			Checksummer::init(&Default::default(), !encryption.is_encrypted()).add(algo)
+		}
+	};
+
 	// If body is small enough, store it directly in the object table
 	// as "inline data". We can then return immediately.
 	if first_block.len() < INLINE_THRESHOLD {
-		let mut md5sum = Md5::new();
-		md5sum.update(&first_block[..]);
-		let data_md5sum = md5sum.finalize();
-
-		let data_sha256sum = sha256sum(&first_block[..]);
+		checksummer.update(&first_block);
+		let checksums = checksummer.finalize();
 
-		ensure_checksum_matches(
-			&data_md5sum,
-			data_sha256sum,
-			content_md5.as_deref(),
-			content_sha256,
-		)?;
+		match checksum_mode {
+			ChecksumMode::Verify(expected) => {
+				checksums.verify(&expected)?;
+			}
+			ChecksumMode::Calculate(algo) => {
+				meta.checksum = checksums.extract(algo);
+			}
+		};
 
 		let size = first_block.len() as u64;
 		check_quotas(ctx, size, existing_object.as_ref()).await?;
 
-		let etag = encryption.etag_from_md5(&data_md5sum);
+		let etag = encryption.etag_from_md5(&checksums.md5);
 		let inline_data = encryption.encrypt_blob(&first_block)?.to_vec();
 
 		let object_version = ObjectVersion {
@@ -140,7 +154,7 @@ pub(crate) async fn save_stream<S: Stream<Item = Result<Bytes, Error>> + Unpin>(
 			timestamp: version_timestamp,
 			state: ObjectVersionState::Complete(ObjectVersionData::Inline(
 				ObjectVersionMeta {
-					encryption: object_encryption,
+					encryption: encryption.encrypt_meta(meta)?,
 					size,
 					etag: etag.clone(),
 				},
@@ -175,7 +189,8 @@ pub(crate) async fn save_stream<S: Stream<Item = Result<Bytes, Error>> + Unpin>(
 		uuid: version_uuid,
 		timestamp: version_timestamp,
 		state: ObjectVersionState::Uploading {
-			encryption: object_encryption.clone(),
+			encryption: encryption.encrypt_meta(meta.clone())?,
+			checksum_algorithm: None, // don't care; overwritten later
 			multipart: false,
 		},
 	};
@@ -196,25 +211,37 @@ pub(crate) async fn save_stream<S: Stream<Item = Result<Bytes, Error>> + Unpin>(
 	);
 	garage.version_table.insert(&version).await?;
 
-	// Transfer data and verify checksum
-	let (total_size, data_md5sum, data_sha256sum, first_block_hash) =
-		read_and_put_blocks(ctx, &version, encryption, 1, first_block, &mut chunker).await?;
+	// Transfer data
+	let (total_size, checksums, first_block_hash) = read_and_put_blocks(
+		ctx,
+		&version,
+		encryption,
+		1,
+		first_block,
+		&mut chunker,
+		checksummer,
+	)
+	.await?;
 
-	ensure_checksum_matches(
-		&data_md5sum,
-		data_sha256sum,
-		content_md5.as_deref(),
-		content_sha256,
-	)?;
+	// Verify checksums are ok / add calculated checksum to metadata
+	match checksum_mode {
+		ChecksumMode::Verify(expected) => {
+			checksums.verify(&expected)?;
+		}
+		ChecksumMode::Calculate(algo) => {
+			meta.checksum = checksums.extract(algo);
+		}
+	};
 
+	// Verify quotas are respsected
 	check_quotas(ctx, total_size, existing_object.as_ref()).await?;
 
 	// Save final object state, marked as Complete
-	let etag = encryption.etag_from_md5(&data_md5sum);
+	let etag = encryption.etag_from_md5(&checksums.md5);
 
 	object_version.state = ObjectVersionState::Complete(ObjectVersionData::FirstBlock(
 		ObjectVersionMeta {
-			encryption: object_encryption,
+			encryption: encryption.encrypt_meta(meta)?,
 			size: total_size,
 			etag: etag.clone(),
 		},
@@ -234,33 +261,6 @@ pub(crate) async fn save_stream<S: Stream<Item = Result<Bytes, Error>> + Unpin>(
 	})
 }
 
-/// Validate MD5 sum against content-md5 header
-/// and sha256sum against signed content-sha256
-pub(crate) fn ensure_checksum_matches(
-	data_md5sum: &[u8],
-	data_sha256sum: garage_util::data::FixedBytes32,
-	content_md5: Option<&str>,
-	content_sha256: Option<garage_util::data::FixedBytes32>,
-) -> Result<(), Error> {
-	if let Some(expected_sha256) = content_sha256 {
-		if expected_sha256 != data_sha256sum {
-			return Err(Error::bad_request(
-				"Unable to validate x-amz-content-sha256",
-			));
-		} else {
-			trace!("Successfully validated x-amz-content-sha256");
-		}
-	}
-	if let Some(expected_md5) = content_md5 {
-		if expected_md5.trim_matches('"') != BASE64_STANDARD.encode(data_md5sum) {
-			return Err(Error::bad_request("Unable to validate content-md5"));
-		} else {
-			trace!("Successfully validated content-md5");
-		}
-	}
-	Ok(())
-}
-
 /// Check that inserting this object with this size doesn't exceed bucket quotas
 pub(crate) async fn check_quotas(
 	ctx: &ReqCtx,
@@ -332,7 +332,8 @@ pub(crate) async fn read_and_put_blocks<S: Stream<Item = Result<Bytes, Error>> +
 	part_number: u64,
 	first_block: Bytes,
 	chunker: &mut StreamChunker<S>,
-) -> Result<(u64, GenericArray<u8, typenum::U16>, Hash, Hash), Error> {
+	checksummer: Checksummer,
+) -> Result<(u64, Checksums, Hash), Error> {
 	let tracer = opentelemetry::global::tracer("garage");
 
 	let (block_tx, mut block_rx) = mpsc::channel::<Result<Bytes, Error>>(2);
@@ -360,20 +361,20 @@ pub(crate) async fn read_and_put_blocks<S: Stream<Item = Result<Bytes, Error>> +
 
 	let (block_tx2, mut block_rx2) = mpsc::channel::<Result<Bytes, Error>>(1);
 	let hash_stream = async {
-		let md5hasher = AsyncHasher::<Md5>::new();
-		let sha256hasher = AsyncHasher::<Sha256>::new();
+		let mut checksummer = checksummer;
 		while let Some(next) = block_rx.recv().await {
 			match next {
 				Ok(block) => {
 					block_tx2.send(Ok(block.clone())).await?;
-					futures::future::join(
-						md5hasher.update(block.clone()),
-						sha256hasher.update(block.clone()),
-					)
+					checksummer = tokio::task::spawn_blocking(move || {
+						checksummer.update(&block);
+						checksummer
+					})
 					.with_context(Context::current_with_span(
 						tracer.start("Hash block (md5, sha256)"),
 					))
-					.await;
+					.await
+					.unwrap()
 				}
 				Err(e) => {
 					block_tx2.send(Err(e)).await?;
@@ -382,10 +383,7 @@ pub(crate) async fn read_and_put_blocks<S: Stream<Item = Result<Bytes, Error>> +
 			}
 		}
 		drop(block_tx2);
-		Ok::<_, mpsc::error::SendError<_>>(futures::join!(
-			md5hasher.finalize(),
-			sha256hasher.finalize()
-		))
+		Ok::<_, mpsc::error::SendError<_>>(checksummer)
 	};
 
 	let (block_tx3, mut block_rx3) = mpsc::channel::<Result<(Bytes, u64, Hash), Error>>(1);
@@ -395,33 +393,28 @@ pub(crate) async fn read_and_put_blocks<S: Stream<Item = Result<Bytes, Error>> +
 			match next {
 				Ok(block) => {
 					let unencrypted_len = block.len() as u64;
-					let block = if encryption.is_encrypted() {
-						let res =
-							tokio::task::spawn_blocking(move || encryption.encrypt_block(block))
-								.with_context(Context::current_with_span(
-									tracer.start("Encrypt block"),
-								))
-								.await
-								.unwrap();
-						match res {
-							Ok(b) => b,
-							Err(e) => {
-								block_tx3.send(Err(e)).await?;
-								break;
+					let res = tokio::task::spawn_blocking(move || {
+						let block = encryption.encrypt_block(block)?;
+						let hash = blake2sum(&block);
+						Ok((block, hash))
+					})
+					.with_context(Context::current_with_span(
+						tracer.start("Encrypt and hash (blake2) block"),
+					))
+					.await
+					.unwrap();
+					match res {
+						Ok((block, hash)) => {
+							if first_block_hash.is_none() {
+								first_block_hash = Some(hash);
 							}
+							block_tx3.send(Ok((block, unencrypted_len, hash))).await?;
+						}
+						Err(e) => {
+							block_tx3.send(Err(e)).await?;
+							break;
 						}
-					} else {
-						block
-					};
-					let hash = async_blake2sum(block.clone())
-						.with_context(Context::current_with_span(
-							tracer.start("Hash block (blake2)"),
-						))
-						.await;
-					if first_block_hash.is_none() {
-						first_block_hash = Some(hash);
 					}
-					block_tx3.send(Ok((block, unencrypted_len, hash))).await?;
 				}
 				Err(e) => {
 					block_tx3.send(Err(e)).await?;
@@ -493,12 +486,10 @@ pub(crate) async fn read_and_put_blocks<S: Stream<Item = Result<Bytes, Error>> +
 	let total_size = final_result?;
 	// unwrap here is ok, because if hasher failed, it is because something failed
 	// later in the pipeline which already caused a return at the ? on previous line
-	let (data_md5sum, data_sha256sum) = stream_hash_result.unwrap();
 	let first_block_hash = block_hash_result.unwrap();
+	let checksums = stream_hash_result.unwrap().finalize();
 
-	let data_sha256sum = Hash::try_from(&data_sha256sum[..]).unwrap();
-
-	Ok((total_size, data_md5sum, data_sha256sum, first_block_hash))
+	Ok((total_size, checksums, first_block_hash))
 }
 
 async fn put_block_and_meta(
@@ -609,7 +600,7 @@ impl Drop for InterruptedCleanup {
 
 // ============ helpers ============
 
-pub(crate) fn get_headers(headers: &HeaderMap<HeaderValue>) -> Result<ObjectVersionHeaders, Error> {
+pub(crate) fn get_headers(headers: &HeaderMap<HeaderValue>) -> Result<HeaderList, Error> {
 	let mut ret = Vec::new();
 
 	// Preserve standard headers
@@ -637,7 +628,7 @@ pub(crate) fn get_headers(headers: &HeaderMap<HeaderValue>) -> Result<ObjectVers
 		}
 	}
 
-	Ok(ObjectVersionHeaders(ret))
+	Ok(ret)
 }
 
 pub(crate) fn next_timestamp(existing_object: Option<&Object>) -> u64 {
diff --git a/src/api/s3/xml.rs b/src/api/s3/xml.rs
index 06f11288..1e569ade 100644
--- a/src/api/s3/xml.rs
+++ b/src/api/s3/xml.rs
@@ -131,6 +131,14 @@ pub struct CompleteMultipartUploadResult {
 	pub key: Value,
 	#[serde(rename = "ETag")]
 	pub etag: Value,
+	#[serde(rename = "ChecksumCRC32")]
+	pub checksum_crc32: Option<Value>,
+	#[serde(rename = "ChecksumCRC32C")]
+	pub checksum_crc32c: Option<Value>,
+	#[serde(rename = "ChecksumSHA1")]
+	pub checksum_sha1: Option<Value>,
+	#[serde(rename = "ChecksumSHA256")]
+	pub checksum_sha256: Option<Value>,
 }
 
 #[derive(Debug, Serialize, PartialEq, Eq)]
@@ -197,6 +205,14 @@ pub struct PartItem {
 	pub part_number: IntValue,
 	#[serde(rename = "Size")]
 	pub size: IntValue,
+	#[serde(rename = "ChecksumCRC32")]
+	pub checksum_crc32: Option<Value>,
+	#[serde(rename = "ChecksumCRC32C")]
+	pub checksum_crc32c: Option<Value>,
+	#[serde(rename = "ChecksumSHA1")]
+	pub checksum_sha1: Option<Value>,
+	#[serde(rename = "ChecksumSHA256")]
+	pub checksum_sha256: Option<Value>,
 }
 
 #[derive(Debug, Serialize, PartialEq, Eq)]
@@ -500,6 +516,10 @@ mod tests {
 			bucket: Value("mybucket".to_string()),
 			key: Value("a/plop".to_string()),
 			etag: Value("\"3858f62230ac3c915f300c664312c11f-9\"".to_string()),
+			checksum_crc32: None,
+			checksum_crc32c: None,
+			checksum_sha1: Some(Value("ZJAnHyG8PeKz9tI8UTcHrJos39A=".into())),
+			checksum_sha256: None,
 		};
 		assert_eq!(
 			to_xml_with_header(&result)?,
@@ -509,6 +529,7 @@ mod tests {
 	<Bucket>mybucket</Bucket>\
 	<Key>a/plop</Key>\
 	<ETag>&quot;3858f62230ac3c915f300c664312c11f-9&quot;</ETag>\
+    <ChecksumSHA1>ZJAnHyG8PeKz9tI8UTcHrJos39A=</ChecksumSHA1>\
 </CompleteMultipartUploadResult>"
 		);
 		Ok(())
@@ -780,12 +801,22 @@ mod tests {
 					last_modified: Value("2010-11-10T20:48:34.000Z".to_string()),
 					part_number: IntValue(2),
 					size: IntValue(10485760),
+					checksum_crc32: None,
+					checksum_crc32c: None,
+					checksum_sha256: Some(Value(
+						"5RQ3A5uk0w7ojNjvegohch4JRBBGN/cLhsNrPzfv/hA=".into(),
+					)),
+					checksum_sha1: None,
 				},
 				PartItem {
 					etag: Value("\"aaaa18db4cc2f85cedef654fccc4a4x8\"".to_string()),
 					last_modified: Value("2010-11-10T20:48:33.000Z".to_string()),
 					part_number: IntValue(3),
 					size: IntValue(10485760),
+					checksum_sha256: None,
+					checksum_crc32c: None,
+					checksum_crc32: Some(Value("ZJAnHyG8=".into())),
+					checksum_sha1: None,
 				},
 			],
 			initiator: Initiator {
@@ -820,12 +851,14 @@ mod tests {
     <LastModified>2010-11-10T20:48:34.000Z</LastModified>\
     <PartNumber>2</PartNumber>\
     <Size>10485760</Size>\
+    <ChecksumSHA256>5RQ3A5uk0w7ojNjvegohch4JRBBGN/cLhsNrPzfv/hA=</ChecksumSHA256>\
   </Part>\
   <Part>\
     <ETag>&quot;aaaa18db4cc2f85cedef654fccc4a4x8&quot;</ETag>\
     <LastModified>2010-11-10T20:48:33.000Z</LastModified>\
     <PartNumber>3</PartNumber>\
     <Size>10485760</Size>\
+    <ChecksumCRC32>ZJAnHyG8=</ChecksumCRC32>\
   </Part>\
   <Initiator>\
       <DisplayName>umat-user-11116a31-17b5-4fb7-9df5-b288870f11xx</DisplayName>\
diff --git a/src/garage/Cargo.toml b/src/garage/Cargo.toml
index 53449a1c..17da68f8 100644
--- a/src/garage/Cargo.toml
+++ b/src/garage/Cargo.toml
@@ -42,6 +42,7 @@ tracing.workspace = true
 tracing-subscriber.workspace = true
 rand.workspace = true
 async-trait.workspace = true
+sha1.workspace = true
 sodiumoxide.workspace = true
 structopt.workspace = true
 git-version.workspace = true
diff --git a/src/garage/tests/s3/multipart.rs b/src/garage/tests/s3/multipart.rs
index 51c9df74..cc424f59 100644
--- a/src/garage/tests/s3/multipart.rs
+++ b/src/garage/tests/s3/multipart.rs
@@ -1,6 +1,7 @@
 use crate::common;
 use aws_sdk_s3::primitives::ByteStream;
-use aws_sdk_s3::types::{CompletedMultipartUpload, CompletedPart};
+use aws_sdk_s3::types::{ChecksumAlgorithm, CompletedMultipartUpload, CompletedPart};
+use base64::prelude::*;
 
 const SZ_5MB: usize = 5 * 1024 * 1024;
 const SZ_10MB: usize = 10 * 1024 * 1024;
@@ -190,6 +191,153 @@ async fn test_multipart_upload() {
 }
 
 #[tokio::test]
+async fn test_multipart_with_checksum() {
+	let ctx = common::context();
+	let bucket = ctx.create_bucket("testmpu-cksum");
+
+	let u1 = vec![0x11; SZ_5MB];
+	let u2 = vec![0x22; SZ_5MB];
+	let u3 = vec![0x33; SZ_5MB];
+
+	let ck1 = calculate_sha1(&u1);
+	let ck2 = calculate_sha1(&u2);
+	let ck3 = calculate_sha1(&u3);
+
+	let up = ctx
+		.client
+		.create_multipart_upload()
+		.bucket(&bucket)
+		.checksum_algorithm(ChecksumAlgorithm::Sha1)
+		.key("a")
+		.send()
+		.await
+		.unwrap();
+	assert!(up.upload_id.is_some());
+
+	let uid = up.upload_id.as_ref().unwrap();
+
+	let p1 = ctx
+		.client
+		.upload_part()
+		.bucket(&bucket)
+		.key("a")
+		.upload_id(uid)
+		.part_number(1)
+		.checksum_sha1(&ck1)
+		.body(ByteStream::from(u1.clone()))
+		.send()
+		.await
+		.unwrap();
+
+	// wrong checksum value should return an error
+	let err1 = ctx
+		.client
+		.upload_part()
+		.bucket(&bucket)
+		.key("a")
+		.upload_id(uid)
+		.part_number(2)
+		.checksum_sha1(&ck1)
+		.body(ByteStream::from(u2.clone()))
+		.send()
+		.await;
+	assert!(err1.is_err());
+
+	let p2 = ctx
+		.client
+		.upload_part()
+		.bucket(&bucket)
+		.key("a")
+		.upload_id(uid)
+		.part_number(2)
+		.checksum_sha1(&ck2)
+		.body(ByteStream::from(u2))
+		.send()
+		.await
+		.unwrap();
+
+	let p3 = ctx
+		.client
+		.upload_part()
+		.bucket(&bucket)
+		.key("a")
+		.upload_id(uid)
+		.part_number(3)
+		.checksum_sha1(&ck3)
+		.body(ByteStream::from(u3.clone()))
+		.send()
+		.await
+		.unwrap();
+
+	{
+		let r = ctx
+			.client
+			.list_parts()
+			.bucket(&bucket)
+			.key("a")
+			.upload_id(uid)
+			.send()
+			.await
+			.unwrap();
+		let parts = r.parts.unwrap();
+		assert_eq!(parts.len(), 3);
+		assert!(parts[0].checksum_crc32.is_none());
+		assert!(parts[0].checksum_crc32_c.is_none());
+		assert!(parts[0].checksum_sha256.is_none());
+		assert_eq!(parts[0].checksum_sha1.as_deref().unwrap(), ck1);
+		assert_eq!(parts[1].checksum_sha1.as_deref().unwrap(), ck2);
+		assert_eq!(parts[2].checksum_sha1.as_deref().unwrap(), ck3);
+	}
+
+	let cmp = CompletedMultipartUpload::builder()
+		.parts(
+			CompletedPart::builder()
+				.part_number(1)
+				.checksum_sha1(&ck1)
+				.e_tag(p1.e_tag.unwrap())
+				.build(),
+		)
+		.parts(
+			CompletedPart::builder()
+				.part_number(2)
+				.checksum_sha1(&ck2)
+				.e_tag(p2.e_tag.unwrap())
+				.build(),
+		)
+		.parts(
+			CompletedPart::builder()
+				.part_number(3)
+				.checksum_sha1(&ck3)
+				.e_tag(p3.e_tag.unwrap())
+				.build(),
+		)
+		.build();
+
+	let expected_checksum = calculate_sha1(
+		&vec![
+			BASE64_STANDARD.decode(&ck1).unwrap(),
+			BASE64_STANDARD.decode(&ck2).unwrap(),
+			BASE64_STANDARD.decode(&ck3).unwrap(),
+		]
+		.concat(),
+	);
+
+	let res = ctx
+		.client
+		.complete_multipart_upload()
+		.bucket(&bucket)
+		.key("a")
+		.upload_id(uid)
+		.checksum_sha1(expected_checksum.clone())
+		.multipart_upload(cmp)
+		.send()
+		.await
+		.unwrap();
+
+	assert_eq!(res.checksum_sha1, Some(expected_checksum));
+}
+
+#[tokio::test]
 async fn test_uploadlistpart() {
 	let ctx = common::context();
 	let bucket = ctx.create_bucket("uploadpart");
@@ -624,3 +772,11 @@ async fn test_uploadpartcopy() {
 	assert_eq!(real_obj.len(), exp_obj.len());
 	assert_eq!(real_obj, exp_obj);
 }
+
+fn calculate_sha1(bytes: &[u8]) -> String {
+	use sha1::{Digest, Sha1};
+
+	let mut hasher = Sha1::new();
+	hasher.update(bytes);
+	BASE64_STANDARD.encode(&hasher.finalize()[..])
+}
diff --git a/src/model/s3/mpu_table.rs b/src/model/s3/mpu_table.rs
index 238cbf11..c9f79caf 100644
--- a/src/model/s3/mpu_table.rs
+++ b/src/model/s3/mpu_table.rs
@@ -17,6 +17,7 @@ pub const PARTS: &str = "parts";
 pub const BYTES: &str = "bytes";
 
 mod v09 {
+	use crate::s3::object_table::ChecksumValue;
 	use garage_util::crdt;
 	use garage_util::data::Uuid;
 	use serde::{Deserialize, Serialize};
@@ -61,6 +62,9 @@ mod v09 {
 		pub version: Uuid,
 		/// ETag of the content of this part (known only once done uploading)
 		pub etag: Option<String>,
+		/// Checksum requested by x-amz-checksum-algorithm
+		#[serde(default)]
+		pub checksum: Option<ChecksumValue>,
 		/// Size of this part (known only once done uploading)
 		pub size: Option<u64>,
 	}
@@ -155,6 +159,11 @@ impl Crdt for MpuPart {
 			(Some(x), Some(y)) if x < y => other.size,
 			(x, _) => x,
 		};
+		self.checksum = match (self.checksum.take(), &other.checksum) {
+			(None, Some(_)) => other.checksum.clone(),
+			(Some(x), Some(y)) if x < *y => other.checksum.clone(),
+			(x, _) => x,
+		};
 	}
 }
 
diff --git a/src/model/s3/object_table.rs b/src/model/s3/object_table.rs
index eedb9615..b2f25803 100644
--- a/src/model/s3/object_table.rs
+++ b/src/model/s3/object_table.rs
@@ -208,6 +208,8 @@ mod v010 {
 		Uploading {
 			/// Indicates whether this is a multipart upload
 			multipart: bool,
+			/// Checksum algorithm to use
+			checksum_algorithm: Option<ChecksumAlgorithm>,
 			/// Encryption params + headers to be included in the final object
 			encryption: ObjectVersionEncryption,
 		},
@@ -247,10 +249,10 @@ mod v010 {
 	#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Debug, Serialize, Deserialize)]
 	pub enum ObjectVersionEncryption {
 		SseC {
-			/// Encrypted serialized ObjectVersionHeaders struct.
+			/// Encrypted serialized ObjectVersionInner struct.
 			/// This is never compressed, just encrypted using AES256-GCM.
 			#[serde(with = "serde_bytes")]
-			headers: Vec<u8>,
+			inner: Vec<u8>,
 			/// Whether data blocks are compressed in addition to being encrypted
 			/// (compression happens before encryption, whereas for non-encrypted
 			/// objects, compression is handled at the level of the block manager)
@@ -258,13 +260,35 @@ mod v010 {
 		},
 		Plaintext {
 			/// Plain-text headers
-			headers: ObjectVersionHeaders,
+			inner: ObjectVersionMetaInner,
 		},
 	}
 
 	/// Vector of headers, as tuples of the format (header name, header value)
 	#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Debug, Serialize, Deserialize)]
-	pub struct ObjectVersionHeaders(pub Vec<(String, String)>);
+	pub struct ObjectVersionMetaInner {
+		pub headers: HeaderList,
+		pub checksum: Option<ChecksumValue>,
+	}
+
+	pub type HeaderList = Vec<(String, String)>;
+
+	#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Copy, Debug, Serialize, Deserialize)]
+	pub enum ChecksumAlgorithm {
+		Crc32,
+		Crc32c,
+		Sha1,
+		Sha256,
+	}
+
+	/// Checksum value for x-amz-checksum-algorithm
+	#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Copy, Debug, Serialize, Deserialize)]
+	pub enum ChecksumValue {
+		Crc32(#[serde(with = "serde_bytes")] [u8; 4]),
+		Crc32c(#[serde(with = "serde_bytes")] [u8; 4]),
+		Sha1(#[serde(with = "serde_bytes")] [u8; 20]),
+		Sha256(#[serde(with = "serde_bytes")] [u8; 32]),
+	}
 
 	impl garage_util::migrate::Migrate for Object {
 		const VERSION_MARKER: &'static [u8] = b"G010s3ob";
@@ -288,6 +312,7 @@ mod v010 {
 				v09::ObjectVersionState::Uploading { multipart, headers } => {
 					ObjectVersionState::Uploading {
 						multipart,
+						checksum_algorithm: None,
 						encryption: migrate_headers(headers),
 					}
 				}
@@ -331,15 +356,18 @@ mod v010 {
 		}
 
 		ObjectVersionEncryption::Plaintext {
-			headers: ObjectVersionHeaders(new_headers),
+			inner: ObjectVersionMetaInner {
+				headers: new_headers,
+				checksum: None,
+			},
 		}
 	}
 
 	// Since ObjectVersionHeaders can now be serialized independently, for the
 	// purpose of being encrypted, we need it to support migrations on its own
 	// as well.
-	impl garage_util::migrate::InitialFormat for ObjectVersionHeaders {
-		const VERSION_MARKER: &'static [u8] = b"G010s3oh";
+	impl garage_util::migrate::InitialFormat for ObjectVersionMetaInner {
+		const VERSION_MARKER: &'static [u8] = b"G010s3om";
 	}
 }
 
@@ -454,6 +482,17 @@ impl Entry<Uuid, String> for Object {
 	}
 }
 
+impl ChecksumValue {
+	pub fn algorithm(&self) -> ChecksumAlgorithm {
+		match self {
+			ChecksumValue::Crc32(_) => ChecksumAlgorithm::Crc32,
+			ChecksumValue::Crc32c(_) => ChecksumAlgorithm::Crc32c,
+			ChecksumValue::Sha1(_) => ChecksumAlgorithm::Sha1,
+			ChecksumValue::Sha256(_) => ChecksumAlgorithm::Sha256,
+		}
+	}
+}
+
 impl Crdt for Object {
 	fn merge(&mut self, other: &Self) {
 		// Merge versions from other into here
diff --git a/src/util/async_hash.rs b/src/util/async_hash.rs
deleted file mode 100644
index 5631ea6b..00000000
--- a/src/util/async_hash.rs
+++ /dev/null
@@ -1,61 +0,0 @@
-use bytes::Bytes;
-use digest::Digest;
-
-use tokio::sync::mpsc;
-use tokio::task::JoinHandle;
-
-use crate::data::*;
-
-/// Compute the sha256 of a slice,
-/// spawning on a tokio thread for CPU-intensive processing
-/// The argument has to be an owned Bytes, as it is moved out to a new thread.
-pub async fn async_sha256sum(data: Bytes) -> Hash {
-	tokio::task::spawn_blocking(move || sha256sum(&data))
-		.await
-		.unwrap()
-}
-
-/// Compute the blake2sum of a slice,
-/// spawning on a tokio thread for CPU-intensive processing.
-/// The argument has to be an owned Bytes, as it is moved out to a new thread.
-pub async fn async_blake2sum(data: Bytes) -> Hash {
-	tokio::task::spawn_blocking(move || blake2sum(&data))
-		.await
-		.unwrap()
-}
-
-// ----
-
-pub struct AsyncHasher<D: Digest> {
-	sendblk: mpsc::Sender<Bytes>,
-	task: JoinHandle<digest::Output<D>>,
-}
-
-impl<D: Digest> AsyncHasher<D> {
-	pub fn new() -> Self {
-		let (sendblk, mut recvblk) = mpsc::channel::<Bytes>(1);
-		let task = tokio::task::spawn_blocking(move || {
-			let mut digest = D::new();
-			while let Some(blk) = recvblk.blocking_recv() {
-				digest.update(&blk[..]);
-			}
-			digest.finalize()
-		});
-		Self { sendblk, task }
-	}
-
-	pub async fn update(&self, b: Bytes) {
-		self.sendblk.send(b).await.unwrap();
-	}
-
-	pub async fn finalize(self) -> digest::Output<D> {
-		drop(self.sendblk);
-		self.task.await.unwrap()
-	}
-}
-
-impl<D: Digest> Default for AsyncHasher<D> {
-	fn default() -> Self {
-		Self::new()
-	}
-}
diff --git a/src/util/lib.rs b/src/util/lib.rs
index 7df77959..8b035ff0 100644
--- a/src/util/lib.rs
+++ b/src/util/lib.rs
@@ -3,7 +3,6 @@
 #[macro_use]
 extern crate tracing;
 
-pub mod async_hash;
 pub mod background;
 pub mod config;
 pub mod crdt;