const (
	emptySHA256                   = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
	streamingContentSHA256        = "STREAMING-AWS4-HMAC-SHA256-PAYLOAD"
	streamingContentSHA256Trailer = "STREAMING-AWS4-HMAC-SHA256-PAYLOAD-TRAILER"
	signV4ChunkedAlgorithm        = "AWS4-HMAC-SHA256-PAYLOAD"
	signV4ChunkedAlgorithmTrailer = "AWS4-HMAC-SHA256-TRAILER"
	streamingContentEncoding      = "aws-chunked"

}

// Verify if the request has AWS Streaming Signature Version '4'. This is only valid for 'PUT' operation.
func isRequestSignStreamingTrailerV4(r *http.Request) bool {
	return r.Header.Get(xhttp.AmzContentSha256) == streamingContentSHA256Trailer &&
		r.Method == http.MethodPut
}

// Verify if the request has AWS Streaming Signature Version '4', with unsigned content and trailer.
func isRequestUnsignedTrailerV4(r *http.Request) bool {