A Golang implementation of HTTP Message Signatures, as defined by RFC 9421 (the former draft-ietf-httpbis-message-signatures).

This is a nearly feature-complete implementation of the RFC, including all test vectors.

Usage

The library provides natural integration points with Go HTTP clients and servers, as well as direct usage of the sign and verify functions.

Below is what a basic client-side integration looks like. Additional examples are available in the API reference.

	// Create a signer and a wrapped HTTP client
	signer, _ := httpsign.NewRSAPSSSigner(*prvKey, httpsign.NewSignConfig(),
		httpsign.Headers("@request-target", "content-digest")) // The Content-Digest header will be auto-generated
	client := httpsign.NewDefaultClient(httpsign.NewClientConfig().SetSignatureName("sig1").SetSigner(signer)) // sign requests, don't verify responses

	// Send an HTTP POST, get response -- signing happens behind the scenes
	body := `{"hello": "world"}`
	res, _ := client.Post(ts.URL, "application/json", bufio.NewReader(strings.NewReader(body)))
	
	// Read the response
	serverText, _ := io.ReadAll(res.Body)
	_ = res.Body.Close()

Notes and Missing Features

• The Accept-Signature header is unimplemented.
• In responses, when using the "wrapped handler" feature, the Content-Type header is only signed if set explicitly by the server. This is different, but arguably more secure, than the normal net.http behavior.