diff --git a/s3tests_boto3/functional/test_s3.py b/s3tests_boto3/functional/test_s3.py
index 47cc525..a8fa059 100644
--- a/s3tests_boto3/functional/test_s3.py
+++ b/s3tests_boto3/functional/test_s3.py
@@ -13434,3 +13434,91 @@ def test_get_object_torrent():
         status, error_code = _get_status_and_error_code(e.response)
         assert status == 404
         assert error_code == 'NoSuchKey'
+
+@pytest.mark.checksum
+def test_object_checksum_sha256():
+    bucket = get_new_bucket()
+    client = get_client()
+
+    key = "myobj"
+    size = 1024
+    body = FakeWriteFile(size, 'A')
+    sha256sum = 'arcu6553sHVAiX4MjW0j7I7vD4w6R+Gz9Ok0Q9lTa+0='
+    response = client.put_object(Bucket=bucket, Key=key, Body=body, ChecksumAlgorithm='SHA256', ChecksumSHA256=sha256sum)
+    assert sha256sum == response['ChecksumSHA256']
+
+    response = client.head_object(Bucket=bucket, Key=key)
+    assert 'ChecksumSHA256' not in response
+    response = client.head_object(Bucket=bucket, Key=key, ChecksumMode='ENABLED')
+    assert sha256sum == response['ChecksumSHA256']
+
+    e = assert_raises(ClientError, client.put_object, Bucket=bucket, Key=key, Body=body, ChecksumAlgorithm='SHA256', ChecksumSHA256='bad')
+    status, error_code = _get_status_and_error_code(e.response)
+    assert status == 400
+    assert error_code == 'InvalidRequest'
+
+@pytest.mark.checksum
+def test_multipart_checksum_sha256():
+    bucket = get_new_bucket()
+    client = get_client()
+
+    key = "mymultipart"
+    response = client.create_multipart_upload(Bucket=bucket, Key=key, ChecksumAlgorithm='SHA256')
+    assert 'SHA256' == response['ChecksumAlgorithm']
+    upload_id = response['UploadId']
+
+    size = 1024
+    body = FakeWriteFile(size, 'A')
+    part_sha256sum = 'arcu6553sHVAiX4MjW0j7I7vD4w6R+Gz9Ok0Q9lTa+0='
+    response = client.upload_part(UploadId=upload_id, Bucket=bucket, Key=key, PartNumber=1, Body=body, ChecksumAlgorithm='SHA256', ChecksumSHA256=part_sha256sum)
+
+    # should reject the bad request checksum
+    e = assert_raises(ClientError, client.complete_multipart_upload, Bucket=bucket, Key=key, UploadId=upload_id, ChecksumSHA256='bad', MultipartUpload={'Parts': [
+        {'ETag': response['ETag'].strip('"'), 'ChecksumSHA256': response['ChecksumSHA256'], 'PartNumber': 1}]})
+    status, error_code = _get_status_and_error_code(e.response)
+    assert status == 400
+    assert error_code == 'InvalidRequest'
+
+    # XXXX re-trying the complete is failing in RGW due to an internal error that appears not caused
+    # checksums;
+    # 2024-04-25T17:47:47.991-0400 7f78e3a006c0  0 req 4931907640780566174 0.011000143s s3:complete_multipart check_previously_completed() ERROR: get_obj_attrs() returned ret=-2
+    # 2024-04-25T17:47:47.991-0400 7f78e3a006c0  2 req 4931907640780566174 0.011000143s s3:complete_multipart completing
+    # 2024-04-25T17:47:47.991-0400 7f78e3a006c0  1 req 4931907640780566174 0.011000143s s3:complete_multipart ERROR: either op_ret is negative (execute failed) or target_obj is null, op_ret: -2200
+    # -2200 turns into 500, InternalError
+
+    key = "mymultipart2"
+    response = client.create_multipart_upload(Bucket=bucket, Key=key, ChecksumAlgorithm='SHA256')
+    assert 'SHA256' == response['ChecksumAlgorithm']
+    upload_id = response['UploadId']
+
+    size = 1024
+    body = FakeWriteFile(size, 'A')
+    part_sha256sum = 'arcu6553sHVAiX4MjW0j7I7vD4w6R+Gz9Ok0Q9lTa+0='
+    response = client.upload_part(UploadId=upload_id, Bucket=bucket, Key=key, PartNumber=1, Body=body, ChecksumAlgorithm='SHA256', ChecksumSHA256=part_sha256sum)
+
+    # should reject the missing part checksum
+    e = assert_raises(ClientError, client.complete_multipart_upload, Bucket=bucket, Key=key, UploadId=upload_id, ChecksumSHA256='bad', MultipartUpload={'Parts': [
+        {'ETag': response['ETag'].strip('"'), 'PartNumber': 1}]})
+    status, error_code = _get_status_and_error_code(e.response)
+    assert status == 400
+    assert error_code == 'InvalidRequest'
+
+    key = "mymultipart3"
+    response = client.create_multipart_upload(Bucket=bucket, Key=key, ChecksumAlgorithm='SHA256')
+    assert 'SHA256' == response['ChecksumAlgorithm']
+    upload_id = response['UploadId']
+
+    size = 1024
+    body = FakeWriteFile(size, 'A')
+    part_sha256sum = 'arcu6553sHVAiX4MjW0j7I7vD4w6R+Gz9Ok0Q9lTa+0='
+    response = client.upload_part(UploadId=upload_id, Bucket=bucket, Key=key, PartNumber=1, Body=body, ChecksumAlgorithm='SHA256', ChecksumSHA256=part_sha256sum)
+
+    composite_sha256sum = 'Ok6Cs5b96ux6+MWQkJO7UBT5sKPBeXBLwvj/hK89smg=-1'
+    response = client.complete_multipart_upload(Bucket=bucket, Key=key, UploadId=upload_id, ChecksumSHA256=composite_sha256sum, MultipartUpload={'Parts': [
+        {'ETag': response['ETag'].strip('"'), 'ChecksumSHA256': response['ChecksumSHA256'], 'PartNumber': 1}]})
+    assert composite_sha256sum == response['ChecksumSHA256']
+
+    response = client.head_object(Bucket=bucket, Key=key)
+    assert 'ChecksumSHA256' not in response
+    response = client.head_object(Bucket=bucket, Key=key, ChecksumMode='ENABLED')
+    assert composite_sha256sum == response['ChecksumSHA256']