Golang 签名

// createSignature 生成签名
// @signStr outId
// @DevRsaPrivateKey 私钥
func (s *Service) CreateSignatureWithMd5(signStr string, privateKey string) (string, error) {
   //如果密钥是urlSafeBase64的话需要处理下
   prvKey := s.base64URLDecode(privateKey)
   keyBytes, err := base64.StdEncoding.DecodeString(prvKey)
   if err != nil {
      fmt.Println("DecodeString:", err)
      return "", err
   }
   privateKey1, err := x509.ParsePKCS8PrivateKey(keyBytes)
   if err != nil {
      fmt.Println("ParsePKCS8PrivateKey", err)
      return "", err
   }
   h := md5.New()
   h.Write([]byte(signStr))
   hash := h.Sum(nil)
   signature, err := rsa.SignPKCS1v15(rand.Reader, privateKey1.(*rsa.PrivateKey), crypto.MD5, hash[:])
   if err != nil {
      fmt.Println("SignPKCS1v15:", err)
      return "", err
   }
   out := base64.RawURLEncoding.EncodeToString(signature)
   return out, nil
}

// RsaVerifySignWithMd5 验签
// @originalData outID
// @signData 签名
// @rsaPublicKey 公钥
func (s *Service) RsaVerifySignWithMd5(originalData, signData, rsaPublicKey string) error {
   sign, err := base64.RawURLEncoding.DecodeString(signData)
   if err != nil {
      fmt.Println("DecodeString:", err)
      return err
   }
   rsaPublicKey = s.base64URLDecode(rsaPublicKey)
   publicString, err := base64.StdEncoding.DecodeString(rsaPublicKey)
   if err != nil {
      fmt.Println("DecodeString")
      return err
   }
   pub, err := x509.ParsePKIXPublicKey(publicString)
   if err != nil {
      fmt.Println("ParsePKIXPublicKey", err)
      return err
   }
   hash := md5.New()
   hash.Write([]byte(originalData))
   return rsa.VerifyPKCS1v15(pub.(*rsa.PublicKey), crypto.MD5, hash.Sum(nil), sign)
}

//因为Base64转码后可能包含有+,/,=这些不安全的URL字符串，所以要进行换字符
// '+' -> '-'
// '/' -> '_'
// '=' -> ''
// 字符串长度不足4倍的位补"="
func (s *Service) base64URLDecode(data string) string {
   var missing = (4 - len(data)%4) % 4
   data += strings.Repeat("=", missing) //字符串长度不足4倍的位补"="
   data = strings.Replace(data, "_", "/", -1)
   data = strings.Replace(data, "-", "+", -1)
   return data
}