verify.go

package main

import (
	"crypto/rand"
	"fmt"
	cose "go.mozilla.org/cose"
)

func main() {
	// create a signer with a new private key
	signer, err := cose.NewSigner(cose.ES256, nil)
	if err != nil {
		panic(fmt.Sprintf(fmt.Sprintf("Error creating signer %s", err)))
	}

	// create a signature
	sig := cose.NewSignature()
	sig.Headers.Unprotected["kid"] = 1
	sig.Headers.Protected["alg"] = "ES256"

	// create a message
	external := []byte("") // optional external data see https://tools.ietf.org/html/rfc8152#section-4.3

	msg := cose.NewSignMessage()
	msg.Payload = []byte("payload to sign")
	msg.AddSignature(sig)

	err = msg.Sign(rand.Reader, external, []cose.Signer{*signer})
	if err == nil {
		fmt.Println(fmt.Sprintf("Message signature (ES256): %x", msg.Signatures[0].SignatureBytes))
	} else {
		panic(fmt.Sprintf("Error signing the message %+v", err))
	}

	// derive a verifier using the signer's public key and COSE algorithm
	verifier := signer.Verifier()

	// Verify
	err = msg.Verify(external, []cose.Verifier{*verifier})
	if err == nil {
		fmt.Println("Message signature verified")
	} else {
		fmt.Println(fmt.Sprintf("Error verifying the message %+v", err))
	}
}