x-amz-sdk-checksum-algorithm, sending it on it's own (with a value of sha1) throws this:InvalidRequest => x-amz-sdk-checksum-algorithm specified, but no corresponding x-amz-checksum-* or x-amz-trailer headers were found.x-amz-checksum-sha1 as well, with the proper value, and it'll upload properly with a 200 OK.