【绝迹篇】RSA加密算法(私钥加签公钥验签)

对于上上篇博客中我讲的一个故事，本文引用: https://www.cnblogs.com/ButterflyEffect/p/9851403.html

故事中提到的关于加密会出现，私钥加密，公钥解密的情况，这种情况我们将它称为【私钥加签，公钥验签】
说句好理解的话：
既然是加密，那肯定是不希望别人知道我的消息，所以只有我才能解密，所以可得出【公钥负责加密，私钥负责解密】
同理，既然是签名，那肯定是不希望有人冒充我发消息，只有我才能发布这个签名，所以可得出【私钥负责加签，公钥负责验签】

由以上得出关于安全性的问题，再举个好例子：
现在有A(私钥A、公钥A)，B(私钥B、公钥B) ,A向B发送消息，用私钥A加签、用公钥B加密，发送给B，B用私钥B解密，然后用公钥A验签。
这样的话就能保证是A发的消息，并且只有B自己才能解密。这样是非常安全的！！！

话不多少，下面直接撸代码，以下代码是实现【私钥加签公钥验签】的功能，公钥加密私钥解密的功能在我其它博客有讲过...

 #region 私钥加密，公钥解密
        /// <summary>
        /// 私钥加密
        /// </summary>
        /// <param name="privateKey">RSA私钥 base64格式</param>
        /// <param name="contentData">待加密的数据</param>
        /// <param name="algorithm">加密算法</param>
        /// <returns></returns>
        public static string EncryptWithPrivateKey(string privateKey, byte[] contentData, string algorithm = "RSA/ECB/PKCS1Padding")
        {
            return Convert.ToBase64String(EncryptWithPrivateKey(Convert.FromBase64String(privateKey), contentData, algorithm));
        }
        /// <summary>
        /// 私钥加密
        /// </summary>
        /// <param name="privateKey">RSA私钥</param>
        /// <param name="contentData">待加密的数据</param>
        /// <param name="algorithm">加密算法</param>
        /// <returns></returns>
        public static byte[] EncryptWithPrivateKey(byte[] privateKey, byte[] contentData, string algorithm = "RSA/ECB/PKCS1Padding")
        {
            RsaPrivateCrtKeyParameters privateKeyParam = (RsaPrivateCrtKeyParameters)PrivateKeyFactory.CreateKey(privateKey);
            return Transform(privateKeyParam, contentData, algorithm, true);
        }
        /// <summary>
        /// 公钥解密
        /// </summary>
        /// <param name="publicKey">RSA公钥  base64格式</param>
        /// <param name="content">待解密数据 base64格式</param>
        /// <param name="encoding">解密出来的数据编码格式，默认UTF-8</param>
        /// <param name="algorithm">加密算法</param>
        /// <returns></returns>
        public static string DecryptWithPublicKey(string publicKey, string content, string encoding = "UTF-8", string algorithm = "RSA/ECB/PKCS1Padding")
        {
            return Encoding.GetEncoding("GB2312").GetString(DecryptWithPublicKey(Convert.FromBase64String(publicKey), Convert.FromBase64String(content), algorithm));
        }
        /// <summary>
        /// 公钥解密
        /// </summary>
        /// <param name="publicKey">RSA公钥</param>
        /// <param name="contentData">待解密数据</param>
        /// <param name="algorithm">加密算法</param>
        /// <returns></returns>
        public static byte[] DecryptWithPublicKey(byte[] publicKey, byte[] contentData, string algorithm = "RSA/ECB/PKCS1Padding")
        {
            RsaKeyParameters publicKeyParam = (RsaKeyParameters)PublicKeyFactory.CreateKey(publicKey);
            return Transform(publicKeyParam, contentData, algorithm, false);
        }
 #endregion
        private static byte[] Transform(AsymmetricKeyParameter key, byte[] contentData, string algorithm, bool forEncryption)
        {
            var c = CipherUtilities.GetCipher(algorithm);
            c.Init(forEncryption, new ParametersWithRandom(key));
            return c.DoFinal(contentData);
        }

顺带提下，这里的第三方RSA引用包可以在【程序包管理器控制台】输入命令提示
PM> Install-Package BouncyCastle
完成包的安装

static void Main(string[] args)
{
            RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
            string xmlPrivateKey = rsa.ToXmlString(true);//XML密钥
            string xmlPublicKey = rsa.ToXmlString(false);//XML公钥

            string str = "测试数据";
            byte[] b = System.Text.Encoding.Default.GetBytes(str);//字符串转字节数组，byte[]

            string EncryptedData = EncryptWithPrivateKey(B(xmlPrivateKey), b);//返回加密后的base64格式数据
            Console.WriteLine("私钥加密结果：" + EncryptedData);
            string DecipheringData = DecryptWithPublicKey(A(xmlPublicKey), EncryptedData);//返回解密后的明文数据
            Console.WriteLine("公钥解密结果：" + DecipheringData);

            Console.ReadLine();
}

//XML格式转base64格式，公钥
public static string A(string xml)
{
            var rsa = new RSACryptoServiceProvider();
            rsa.FromXmlString(xml);
            var p = rsa.ExportParameters(false);
            RsaKeyParameters key = new RsaKeyParameters(false, new BigInteger(1, p.Modulus), new BigInteger(1, p.Exponent));

            SubjectPublicKeyInfo publicKeyInfo = SubjectPublicKeyInfoFactory.CreateSubjectPublicKeyInfo(key);
            byte[] serializedPublicBytes = publicKeyInfo.ToAsn1Object().GetDerEncoded();
            string publicKey = Convert.ToBase64String(serializedPublicBytes);
            return publicKey;
}

//XML格式转base64格式，私钥
public static string B(string xml)
{
            var rsa = new RSACryptoServiceProvider();
            rsa.FromXmlString(xml);
            var p = rsa.ExportParameters(true);
            var key = new RsaPrivateCrtKeyParameters(
                new BigInteger(1, p.Modulus), new BigInteger(1, p.Exponent), new BigInteger(1, p.D),
                new BigInteger(1, p.P), new BigInteger(1, p.Q), new BigInteger(1, p.DP), new BigInteger(1, p.DQ),
                new BigInteger(1, p.InverseQ));

            PrivateKeyInfo privateKeyInfo = PrivateKeyInfoFactory.CreatePrivateKeyInfo(key);
            byte[] serializedPrivateBytes = privateKeyInfo.ToAsn1Object().GetEncoded();
            string privateKey = Convert.ToBase64String(serializedPrivateBytes);
            return privateKey;
}

最后加密测试可以在这个网站去测试 http://tool.chacuo.net/cryptrsapubkey