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);}#endregionprivate 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