For the ETag, yes and no that it's an MD5 of the object depending on encryption and multipart upload: https://docs.aws.amazon.com/AmazonS3/latest/API/RESTCommon

For the ETag, yes and no that it's an MD5 of the object depending on encryption and multipart upload: https://docs.aws.amazon.com/AmazonS3/latest/API/RESTCommonResponseHeaders.html https://docs.aws.amazon.com/AmazonS3/latest/API/RESTCommonRe... For the object upload, AWSv4 request signature uses SHA256 on the payload/object, but I don't know if S3 also computes & compares the digest or just uses the x-amz-content-sha256 header value.