VerifyPKCS1v15 in Go

Posted by GoDoc

Public (Editable by Users)

VerifyPKCS1v15 verifies an RSA PKCS#1 v1.5 signature. hashed is the result of hashing the input message using the given hash function and sig is the signature. A valid signature is indicated by returning a nil error. If hash is zero then hashed is used directly. This isn't advisable except for interoperability.

Language Go

Dependencies

import "crypto"

import "crypto/sha256"

import "encoding/hex"

Edit

main.go

package main

import (
	"crypto"
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"os"
)

func main() {
	message := []byte("message to be signed")
	signature, _ := hex.DecodeString("ad2766728615cc7a746cc553916380ca7bfa4f8983b990913bc69eb0556539a350ff0f8fe65ddfd3ebe91fe1c299c2fac135bc8c61e26be44ee259f2f80c1530")

	// Only small messages can be signed directly; thus the hash of a
	// message, rather than the message itself, is signed. This requires
	// that the hash function be collision resistant. SHA-256 is the
	// least-strong hash function that should be used for this at the time
	// of writing (2016).
	hashed := sha256.Sum256(message)

	err := VerifyPKCS1v15(&rsaPrivateKey.PublicKey, crypto.SHA256, hashed[:], signature)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Error from verification: %s\n", err)
		return
	}

	// signature is a valid signature of message from the public key.
}

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