Golang rsa 验证

一下代码用于rsa 签名的验签，

签名可以用其他语言产生。也可以用golang生成。

package mainimport ("crypto""crypto/rsa""crypto/sha256""crypto/x509""encoding/pem""errors""fmt"
)func ParseRsaPublicKeyFromPemStr(pubPEM string) (*rsa.PublicKey, error) {block, _ := pem.Decode([]byte(pubPEM))if block == nil {return nil, errors.New("failed to parse PEM block containing the key")}pub, err := x509.ParsePKCS1PublicKey(block.Bytes)if err != nil {return nil, err}return pub, nil// switch pub := pub.(type) {// case *rsa.PublicKey:// 	return pub, nil// default:// 	break // fall through// }// return nil, errors.New("Key type is not RSA")
}func main() {// The GenerateKey method takes in a reader that returns random bits, and// the number of bits// privateKey, err := rsa.GenerateKey(rand.Reader, 2048)// if err != nil {// 	panic(err)// }// The public key is a part of the *rsa.PrivateKey struct// publicKey := privateKey.PublicKeypublicKey, err := ParseRsaPublicKeyFromPemStr(`-----BEGIN RSA PUBLIC KEY-----
MIIBxxxxxx
-----END RSA PUBLIC KEY-----`)if err != nil {panic(err)}// // use the public and private keys// // ...// // https://play.golang.org/p/tldFUt2c4nx// modulusBytes := base64.StdEncoding.EncodeToString(privateKey.N.Bytes())// privateExponentBytes := base64.StdEncoding.EncodeToString(privateKey.D.Bytes())// fmt.Println(modulusBytes)// fmt.Println(privateExponentBytes)// fmt.Println(publicKey.E)// encryptedBytes, err := rsa.EncryptOAEP(// 	sha256.New(),// 	rand.Reader,// 	&publicKey,// 	[]byte("super secret message111"),// 	nil)// if err != nil {// 	panic(err)// }// fmt.Println("encrypted bytes: ", encryptedBytes)// // The first argument is an optional random data generator (the rand.Reader we used before)// // we can set this value as nil// // The OEAPOptions in the end signify that we encrypted the data using OEAP, and that we used// // SHA256 to hash the input.// decryptedBytes, err := privateKey.Decrypt(nil, encryptedBytes, &rsa.OAEPOptions{Hash: crypto.SHA256})// if err != nil {// 	panic(err)// }// // We get back the original information in the form of bytes, which we// // the cast to a string and print// fmt.Println("decrypted message: ", string(decryptedBytes))msg := []byte(`{"user_agent":"test"}`)// // Before signing, we need to hash our message// // The hash is what we actually signmsgHash := sha256.New()_, err = msgHash.Write(msg)if err != nil {panic(err)}msgHashSum := msgHash.Sum(nil)// // In order to generate the signature, we provide a random number generator,// // our private key, the hashing algorithm that we used, and the hash sum// // of our message// signature, err := rsa.SignPSS(rand.Reader, privateKey, crypto.SHA256, msgHashSum, nil)// if err != nil {// 	panic(err)// }signature := []byte{27, 79, , 8}// To verify the signature, we provide the public key, the hashing algorithm// the hash sum of our message and the signature we generated previously// there is an optional "options" parameter which can omit for nowerr = rsa.VerifyPSS(publicKey, crypto.SHA256, msgHashSum, signature, nil)if err != nil {fmt.Println("could not verify signature: ", err)return}// If we don't get any error from the `VerifyPSS` method, that means our// signature is validfmt.Println("signature verified")
}