RSA加密解密等用法

rsa是非对称加密，有公钥和私钥

公钥用于加密，私钥用于解密，私钥无法加密，但是私钥可以对内容签名，公钥可以对签名进行验证，这是rsa常用的使用场景

如果你想加密一小段关键的信息，那么你可以用公钥进行加密，对方收到后用私钥进行解密。

如果你想发送一段文字，内容很长，你并不需要对内容进行加密，只是想用私钥对内容进行数字签名，对方收到你发的信息后，可以通过公钥验证签名来证实这段信息是不是你发的，并且发的消息有没有被篡改过。

所以这是rsa基本的两种使用场景。

    public class RSACryption
    {
        #region RSA 加密解密

        #region RSA 的密钥产生

        /// <summary>
        /// RSA产生密钥
        /// </summary>
        /// <param name="xmlKeys">私钥</param>
        /// <param name="xmlPublicKey">公钥</param>
        public void RSAKey(out string xmlKeys, out string xmlPublicKey)
        {
            try
            {
                System.Security.Cryptography.RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
                xmlKeys = rsa.ToXmlString(true);
                xmlPublicKey = rsa.ToXmlString(false);
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

        /// <summary>
        /// 生成密钥文件
        /// </summary>
        public void RSACreateKeyFile()
        {
            try
            {
                RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
                using (StreamWriter writer = new StreamWriter("PrivateKey.key"))  //这个文件要保密...
                {
                    writer.WriteLine(rsa.ToXmlString(true));
                }
                using (StreamWriter writer = new StreamWriter("PublicKey.key"))
                {
                    writer.WriteLine(rsa.ToXmlString(false));
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

        /// <summary>
        /// 读取可执行目录下的key文件内容
        /// </summary>
        /// <param name="directory"></param>
        /// <returns></returns>
        public string ReadKeyFile(string directory)
        {
            try
            {
                string key = string.Empty;
                //查找目录下的.KEY后缀文件 获取密钥
                DirectoryInfo directoryInfo = new DirectoryInfo(directory);
                var keyFiles = directoryInfo.GetFiles("*.KEY", SearchOption.TopDirectoryOnly).OrderByDescending(m => m.CreationTime).ToList();
                if (keyFiles.Any())
                {
                    var keyFile = keyFiles[0];
                    key = ReadFile(keyFile.FullName);
                    return key;
                }
                else
                {
                    return string.Empty;
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

        /// <summary>
        /// 获取可执行目录下的key文件内容
        /// </summary>
        /// <param name="directory"></param>
        /// <param name="keyFileName"></param>
        /// <returns></returns>
        public string ReadKeyFile(string directory, string keyFileName)
        {
            try
            {
                string key = string.Empty;
                //查找目录下的.KEY后缀文件 获取密钥
                DirectoryInfo directoryInfo = new DirectoryInfo(directory);
                var keyFiles = directoryInfo.GetFiles(keyFileName, SearchOption.TopDirectoryOnly).OrderByDescending(m => m.CreationTime).ToList();
                if (keyFiles.Any())
                {
                    var keyFile = keyFiles[0];
                    key = ReadFile(keyFile.FullName);
                    return key;
                }
                else
                {
                    return string.Empty;
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }


        private string ReadFile(string path)
        {
            StringBuilder sb = new StringBuilder();
            try
            {
                using (StreamReader sr = new StreamReader(path))
                {
                    string line;

                    // 从文件读取并显示行，直到文件的末尾 
                    while ((line = sr.ReadLine()) != null)
                    {
                        sb.Append(line);
                    }
                }
                return sb.ToString();
            }
            catch (Exception e)
            {
                throw e;
            }
        }

        #endregion

        #region RSA加密函数
        /// <summary>
        /// RSA的加密函数
        /// </summary>
        /// <param name="xmlPublicKey">公钥</param>
        /// <param name="encryptString">待加密的字符串</param>
        /// <returns></returns>
        public string RSAEncrypt(string xmlPublicKey, string encryptString)
        {
            try
            {
                byte[] PlainTextBArray;
                byte[] CypherTextBArray;
                string Result;
                System.Security.Cryptography.RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
                rsa.FromXmlString(xmlPublicKey);
                PlainTextBArray = Encoding.UTF8.GetBytes(encryptString);
                CypherTextBArray = rsa.Encrypt(PlainTextBArray, false);
                Result = Convert.ToBase64String(CypherTextBArray);
                return Result;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

        /// <summary>
        /// RSA的加密函数 
        /// </summary>
        /// <param name="xmlPublicKey">公钥</param>
        /// <param name="EncryptString">待加密的字节数组</param>
        /// <returns></returns>
        public string RSAEncrypt(string xmlPublicKey, byte[] EncryptString)
        {
            try
            {
                byte[] CypherTextBArray;
                string Result;
                System.Security.Cryptography.RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
                rsa.FromXmlString(xmlPublicKey);
                CypherTextBArray = rsa.Encrypt(EncryptString, false);
                Result = Convert.ToBase64String(CypherTextBArray);
                return Result;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }
        #endregion

        #region RSA的解密函数        
        /// <summary>
        /// RSA的解密函数
        /// </summary>
        /// <param name="xmlPrivateKey">私钥</param>
        /// <param name="decryptString">待解密的字符串</param>
        /// <returns></returns>
        public string RSADecrypt(string xmlPrivateKey, string decryptString)
        {
            try
            {
                byte[] PlainTextBArray;
                byte[] DypherTextBArray;
                string Result;
                System.Security.Cryptography.RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
                rsa.FromXmlString(xmlPrivateKey);
                PlainTextBArray = Convert.FromBase64String(decryptString);
                DypherTextBArray = rsa.Decrypt(PlainTextBArray, false);
                Result = Encoding.UTF8.GetString(DypherTextBArray);
                return Result;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }
        /// <summary>
        /// RSA的解密函数 
        /// </summary>
        /// <param name="xmlPrivateKey">私钥</param>
        /// <param name="DecryptString">待解密的字节数组</param>
        /// <returns></returns>
        public string RSADecrypt(string xmlPrivateKey, byte[] DecryptString)
        {
            try
            {
                byte[] DypherTextBArray;
                string Result;
                System.Security.Cryptography.RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
                rsa.FromXmlString(xmlPrivateKey);
                DypherTextBArray = rsa.Decrypt(DecryptString, false);
                Result = Encoding.UTF8.GetString(DypherTextBArray);
                return Result;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }
        #endregion

        #endregion


        #region RSA数字签名

        #region 获取Hash描述表        
        /// <summary>
        /// 获取Hash描述表
        /// </summary>
        /// <param name="strSource">待签名的字符串</param>
        /// <param name="HashData">Hash描述</param>
        /// <returns></returns>
        public byte[] GetHashByte(string strSource)
        {
            try
            {
                byte[] Buffer;
                System.Security.Cryptography.HashAlgorithm MD5 = System.Security.Cryptography.HashAlgorithm.Create("MD5");
                Buffer = System.Text.Encoding.UTF8.GetBytes(strSource);
                return MD5.ComputeHash(Buffer);
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

        /// <summary>
        /// 获取Hash描述表
        /// </summary>
        /// <param name="strSource"></param>
        /// <returns></returns>
        public string GetHashStr(string strSource)
        {
            try
            {
                //从字符串中取得Hash描述 
                byte[] Buffer;
                byte[] HashData;
                System.Security.Cryptography.HashAlgorithm MD5 = System.Security.Cryptography.HashAlgorithm.Create("MD5");
                Buffer = System.Text.Encoding.UTF8.GetBytes(strSource);
                HashData = MD5.ComputeHash(Buffer);
                return Convert.ToBase64String(HashData);
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

        /// <summary>
        /// 获取Hash描述表
        /// </summary>
        /// <param name="objFile"></param>
        /// <returns></returns>
        public byte[] GetHashByte(System.IO.FileStream objFile)
        {
            try
            {
                //从文件中取得Hash描述 
                System.Security.Cryptography.HashAlgorithm MD5 = System.Security.Cryptography.HashAlgorithm.Create("MD5");
                byte[] HashData = MD5.ComputeHash(objFile);
                objFile.Close();
                return HashData;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

        /// <summary>
        /// 获取Hash描述表
        /// </summary>
        /// <param name="objFile"></param>
        /// <returns></returns>
        public string GetHashStr(System.IO.FileStream objFile)
        {
            try
            {
                //从文件中取得Hash描述 
                byte[] HashData;
                System.Security.Cryptography.HashAlgorithm MD5 = System.Security.Cryptography.HashAlgorithm.Create("MD5");
                HashData = MD5.ComputeHash(objFile);
                objFile.Close();
                return Convert.ToBase64String(HashData);
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }
        #endregion

        #region RSA签名


        /// <summary>
        /// RSA签名
        /// </summary>
        /// <param name="strKeyPrivate"></param>
        /// <param name="HashbyteSignature"></param>
        /// <returns></returns>
        public string Signature(string strKeyPrivate, byte[] HashbyteSignature)
        {
            try
            {
                byte[] EncryptedSignatureData;
                System.Security.Cryptography.RSACryptoServiceProvider RSA = new System.Security.Cryptography.RSACryptoServiceProvider();
                RSA.FromXmlString(strKeyPrivate);
                System.Security.Cryptography.RSAPKCS1SignatureFormatter RSAFormatter = new System.Security.Cryptography.RSAPKCS1SignatureFormatter(RSA);
                //设置签名的算法为MD5 
                RSAFormatter.SetHashAlgorithm("MD5");
                //执行签名 
                EncryptedSignatureData = RSAFormatter.CreateSignature(HashbyteSignature);
                return Convert.ToBase64String(EncryptedSignatureData);
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }



        /// <summary>
        /// RSA签名
        /// </summary>
        /// <param name="strKeyPrivate"></param>
        /// <param name="strHashbyteSignature"></param>
        /// <returns></returns>
        public string Signature(string strKeyPrivate, string strHashbyteSignature)
        {
            try
            {
                byte[] HashbyteSignature;
                byte[] EncryptedSignatureData;
                HashbyteSignature = Convert.FromBase64String(strHashbyteSignature);
                System.Security.Cryptography.RSACryptoServiceProvider RSA = new System.Security.Cryptography.RSACryptoServiceProvider();
                RSA.FromXmlString(strKeyPrivate);
                System.Security.Cryptography.RSAPKCS1SignatureFormatter RSAFormatter = new System.Security.Cryptography.RSAPKCS1SignatureFormatter(RSA);
                //设置签名的算法为MD5 
                RSAFormatter.SetHashAlgorithm("MD5");
                //执行签名 
                EncryptedSignatureData = RSAFormatter.CreateSignature(HashbyteSignature);
                return Convert.ToBase64String(EncryptedSignatureData);
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }
        #endregion

        #region RSA 签名验证
        /// <summary>
        /// RSA签名验证
        /// </summary>
        /// <param name="strKeyPublic">公钥</param>
        /// <param name="HashbyteDeformatter">Hash描述</param>
        /// <param name="DeformatterData">签名后的结果</param>
        /// <returns></returns>
        public bool SignatureVerify(string strKeyPublic, byte[] HashbyteDeformatter, byte[] DeformatterData)
        {
            try
            {
                System.Security.Cryptography.RSACryptoServiceProvider RSA = new System.Security.Cryptography.RSACryptoServiceProvider();
                RSA.FromXmlString(strKeyPublic);
                System.Security.Cryptography.RSAPKCS1SignatureDeformatter RSADeformatter = new System.Security.Cryptography.RSAPKCS1SignatureDeformatter(RSA);
                //指定解密的时候HASH算法为MD5 
                RSADeformatter.SetHashAlgorithm("MD5");
                if (RSADeformatter.VerifySignature(HashbyteDeformatter, DeformatterData))
                {
                    return true;
                }
                else
                {
                    return false;
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }
        /// <summary>
        /// RSA签名验证
        /// </summary>
        /// <param name="strKeyPublic">公钥</param>
        /// <param name="strHashbyteDeformatter">Hash描述</param>
        /// <param name="DeformatterData">签名后的结果</param>
        /// <returns></returns>
        public bool SignatureVerify(string strKeyPublic, string strHashbyteDeformatter, byte[] DeformatterData)
        {
            try
            {
                byte[] HashbyteDeformatter;
                HashbyteDeformatter = Convert.FromBase64String(strHashbyteDeformatter);
                System.Security.Cryptography.RSACryptoServiceProvider RSA = new System.Security.Cryptography.RSACryptoServiceProvider();
                RSA.FromXmlString(strKeyPublic);
                System.Security.Cryptography.RSAPKCS1SignatureDeformatter RSADeformatter = new System.Security.Cryptography.RSAPKCS1SignatureDeformatter(RSA);
                //指定解密的时候HASH算法为MD5 
                RSADeformatter.SetHashAlgorithm("MD5");
                if (RSADeformatter.VerifySignature(HashbyteDeformatter, DeformatterData))
                {
                    return true;
                }
                else
                {
                    return false;
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }
        /// <summary>
        /// RSA签名验证
        /// </summary>
        /// <param name="strKeyPublic">公钥</param>
        /// <param name="HashbyteDeformatter">Hash描述</param>
        /// <param name="strDeformatterData">签名后的结果</param>
        /// <returns></returns>
        public bool SignatureVerify(string strKeyPublic, byte[] HashbyteDeformatter, string strDeformatterData)
        {
            try
            {
                byte[] DeformatterData;
                System.Security.Cryptography.RSACryptoServiceProvider RSA = new System.Security.Cryptography.RSACryptoServiceProvider();
                RSA.FromXmlString(strKeyPublic);
                System.Security.Cryptography.RSAPKCS1SignatureDeformatter RSADeformatter = new System.Security.Cryptography.RSAPKCS1SignatureDeformatter(RSA);
                //指定解密的时候HASH算法为MD5 
                RSADeformatter.SetHashAlgorithm("MD5");
                DeformatterData = Convert.FromBase64String(strDeformatterData);
                if (RSADeformatter.VerifySignature(HashbyteDeformatter, DeformatterData))
                {
                    return true;
                }
                else
                {
                    return false;
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }
        /// <summary>
        /// RSA签名验证
        /// </summary>
        /// <param name="strKeyPublic">公钥</param>
        /// <param name="strHashbyteDeformatter">Hash描述</param>
        /// <param name="strDeformatterData">签名后的结果</param>
        /// <returns></returns>
        public bool SignatureVerify(string strKeyPublic, string strHashbyteDeformatter, string strDeformatterData)
        {
            try
            {
                byte[] DeformatterData;
                byte[] HashbyteDeformatter;
                HashbyteDeformatter = Convert.FromBase64String(strHashbyteDeformatter);
                System.Security.Cryptography.RSACryptoServiceProvider RSA = new System.Security.Cryptography.RSACryptoServiceProvider();
                RSA.FromXmlString(strKeyPublic);
                System.Security.Cryptography.RSAPKCS1SignatureDeformatter RSADeformatter = new System.Security.Cryptography.RSAPKCS1SignatureDeformatter(RSA);
                //指定解密的时候HASH算法为MD5 
                RSADeformatter.SetHashAlgorithm("MD5");
                DeformatterData = Convert.FromBase64String(strDeformatterData);
                if (RSADeformatter.VerifySignature(HashbyteDeformatter, DeformatterData))
                {
                    return true;
                }
                else
                {
                    return false;
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }
        #endregion

        #endregion
    }