.net下几种常用的对称加解密

加密解密算法，太常用了，可是实在忍受不了十次八次之后还是要重头写，总是能告诉我原来的算法不好用（实际是压根不会用）的情况，不如直接写出来，再有人要直接给他看看，也顺便记录下算法，方便下新手大众。

DES算法：这算是大家非常常用的对称算法了，很多人都在用这个。

private static string DesKey = @"P@+#wG+Z";

/// <summary>
        /// DES加密字符串
        /// </summary>
        /// <param name="encryptString">待加密的字符串</param>
        /// <param name="encryptKey">加密密钥,要求为8位</param>
        /// <returns>加密成功返回加密后的字符串，失败返回源串</returns>
        public static string EncryptDES(string encryptString, string encryptKey)
        {
            try
            {
                byte[] rgbKey = Encoding.UTF8.GetBytes(encryptKey.Substring(, ));
                byte[] rgbIV = Keys;
                byte[] inputByteArray = Encoding.UTF8.GetBytes(encryptString);
                DESCryptoServiceProvider dCSP = new DESCryptoServiceProvider();
                MemoryStream mStream = new MemoryStream();
                CryptoStream cStream = new CryptoStream(mStream, dCSP.CreateEncryptor(rgbKey, rgbIV), CryptoStreamMode.Write);
                cStream.Write(inputByteArray, , inputByteArray.Length);
                cStream.FlushFinalBlock();
                return Convert.ToBase64String(mStream.ToArray());
            }
            catch
            {
                return encryptString;
            }
        }

        /// <summary>
        /// DES解密字符串
        /// </summary>
        /// <param name="decryptString">待解密的字符串</param>
        /// <param name="decryptKey">解密密钥,要求为8位,和加密密钥相同</param>
        /// <returns>解密成功返回解密后的字符串，失败返源串</returns>
        public static string DecryptDES(string decryptString, string decryptKey)
        {
            try
            {
                byte[] rgbKey = Encoding.UTF8.GetBytes(decryptKey);
                byte[] rgbIV = Keys;
                byte[] inputByteArray = Convert.FromBase64String(decryptString);
                DESCryptoServiceProvider DCSP = new DESCryptoServiceProvider();
                MemoryStream mStream = new MemoryStream();
                CryptoStream cStream = new CryptoStream(mStream, DCSP.CreateDecryptor(rgbKey, rgbIV), CryptoStreamMode.Write);
                cStream.Write(inputByteArray, , inputByteArray.Length);
                cStream.FlushFinalBlock();
                return Encoding.UTF8.GetString(mStream.ToArray());
            }
            catch
            {
                return decryptString;
            }
        } 

DesKey 就是秘钥，这个看自己喜欢了，鄙人也曾经用过“wlyzdhp”之类的秘钥。

AES算法：也是常用的对称算法，安全系数比DES好一点。个人很推荐使用。

private static string AesKey = @")O[NB]6,YF}+efcaj{+oESb9d8>Z'e9M";

 /// <summary>
        /// AES 加密(高级加密标准，是下一代的加密算法标准，速度快，安全级别高，目前 AES 标准的一个实现是 Rijndael 算法)
        /// </summary>
        /// <param name="EncryptString">待加密密文</param>
        /// <param name="EncryptKey">加密密钥</param>
        /// <returns></returns>
        public static string AESEncrypt(string EncryptString, string EncryptKey)
        {
            if (string.IsNullOrEmpty(EncryptString)) { throw (new Exception("密文不得为空")); }

            if (string.IsNullOrEmpty(EncryptKey)) { throw (new Exception("密钥不得为空")); }

            string m_strEncrypt = "";

            byte[] m_btIV = Convert.FromBase64String("Rkb4jvUy/ye7Cd7k89QQgQ==");

            Rijndael m_AESProvider = Rijndael.Create();

            try
            {
                byte[] m_btEncryptString = Encoding.Default.GetBytes(EncryptString);

                MemoryStream m_stream = new MemoryStream();

                CryptoStream m_csstream = new CryptoStream(m_stream, m_AESProvider.CreateEncryptor(Encoding.Default.GetBytes(EncryptKey), m_btIV), CryptoStreamMode.Write);

                m_csstream.Write(m_btEncryptString, , m_btEncryptString.Length);

                m_csstream.FlushFinalBlock();

                m_strEncrypt = Convert.ToBase64String(m_stream.ToArray());

                m_stream.Close(); m_stream.Dispose();

                m_csstream.Close(); m_csstream.Dispose();
            }
            catch (IOException ex) { throw ex; }
            catch (CryptographicException ex) { throw ex; }
            catch (ArgumentException ex) { throw ex; }
            catch (Exception ex) { throw ex; }
            finally { m_AESProvider.Clear(); }

            return m_strEncrypt;
        }
        /// <summary>
        /// AES 解密(高级加密标准，是下一代的加密算法标准，速度快，安全级别高，目前 AES 标准的一个实现是 Rijndael 算法)
        /// </summary>
        /// <param name="DecryptString">待解密密文</param>
        /// <param name="DecryptKey">解密密钥</param>
        /// <returns></returns>
        public static string AESDecrypt(string DecryptString, string DecryptKey)
        {
            if (string.IsNullOrEmpty(DecryptString)) { throw (new Exception("密文不得为空")); }

            if (string.IsNullOrEmpty(DecryptKey)) { throw (new Exception("密钥不得为空")); }

            string m_strDecrypt = "";

            byte[] m_btIV = Convert.FromBase64String("Rkb4jvUy/ye7Cd7k89QQgQ==");

            Rijndael m_AESProvider = Rijndael.Create();

            try
            {
                byte[] m_btDecryptString = Convert.FromBase64String(DecryptString);

                MemoryStream m_stream = new MemoryStream();

                CryptoStream m_csstream = new CryptoStream(m_stream, m_AESProvider.CreateDecryptor(Encoding.Default.GetBytes(DecryptKey), m_btIV), CryptoStreamMode.Write);

                m_csstream.Write(m_btDecryptString, , m_btDecryptString.Length);

                m_csstream.FlushFinalBlock();

                m_strDecrypt = Encoding.Default.GetString(m_stream.ToArray());

                m_stream.Close(); m_stream.Dispose();

                m_csstream.Close(); m_csstream.Dispose();
            }
            catch (IOException ex) { throw ex; }
            catch (CryptographicException ex) { throw ex; }
            catch (ArgumentException ex) { throw ex; }
            catch (Exception ex) { throw ex; }
            finally { m_AESProvider.Clear(); }

            return m_strDecrypt;
        } 

同上，不解释了。

RSA算法：RSA算法是用一套公钥秘钥进行加密解密的，从安全机制上来说比上面两种好，不过这种算法是基于两个大质数乘积互质原则来进行加密解密的，效率上跟公钥秘钥的大小有关，看官们可以根据情况适用，这里只给出了一套我现在常用的一套公钥秘钥，公钥秘钥网上有相关的生成软件，各位可以自行下载使用。

        /// <summary>
        /// RSA加密
        /// </summary>
        /// <param name="publickey"></param>
        /// <param name="content"></param>
        /// <returns></returns>
        public static string RSAEncrypt(string publickey, string content)
        {
            publickey = @"<RSAKeyValue><Modulus>5m9m14XH3oqLJ8bNGw9e4rGpXpcktv9MSkHSVFVMjHbfv+SJ5v0ubqQxa5YjLN4vc49z7SVju8s0X4gZ6AzZTn06jzWOgyPRV54Q4I0DCYadWW4Ze3e+BOtwgVU1Og3qHKn8vygoj40J6U85Z/PTJu3hN1m75Zr195ju7g9v4Hk=</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>";
            RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
            byte[] cipherbytes;
            rsa.FromXmlString(publickey);
            cipherbytes = rsa.Encrypt(Encoding.UTF8.GetBytes(content), false);

            return Convert.ToBase64String(cipherbytes);
        }

        /// <summary>
        /// RSA解密
        /// </summary>
        /// <param name="privatekey"></param>
        /// <param name="content"></param>
        /// <returns></returns>
        public static string RSADecrypt(string privatekey, string content)
        {
            privatekey = @"<RSAKeyValue><Modulus>5m9m14XH3oqLJ8bNGw9e4rGpXpcktv9MSkHSVFVMjHbfv+SJ5v0ubqQxa5YjLN4vc49z7SVju8s0X4gZ6AzZTn06jzWOgyPRV54Q4I0DCYadWW4Ze3e+BOtwgVU1Og3qHKn8vygoj40J6U85Z/PTJu3hN1m75Zr195ju7g9v4Hk=</Modulus><Exponent>AQAB</Exponent><P>/hf2dnK7rNfl3lbqghWcpFdu778hUpIEBixCDL5WiBtpkZdpSw90aERmHJYaW2RGvGRi6zSftLh00KHsPcNUMw==</P><Q>6Cn/jOLrPapDTEp1Fkq+uz++1Do0eeX7HYqi9rY29CqShzCeI7LEYOoSwYuAJ3xA/DuCdQENPSoJ9KFbO4Wsow==</Q><DP>ga1rHIJro8e/yhxjrKYo/nqc5ICQGhrpMNlPkD9n3CjZVPOISkWF7FzUHEzDANeJfkZhcZa21z24aG3rKo5Qnw==</DP><DQ>MNGsCB8rYlMsRZ2ek2pyQwO7h/sZT8y5ilO9wu08Dwnot/7UMiOEQfDWstY3w5XQQHnvC9WFyCfP4h4QBissyw==</DQ><InverseQ>EG02S7SADhH1EVT9DD0Z62Y0uY7gIYvxX/uq+IzKSCwB8M2G7Qv9xgZQaQlLpCaeKbux3Y59hHM+KpamGL19Kg==</InverseQ><D>vmaYHEbPAgOJvaEXQl+t8DQKFT1fudEysTy31LTyXjGu6XiltXXHUuZaa2IPyHgBz0Nd7znwsW/S44iql0Fen1kzKioEL3svANui63O3o5xdDeExVM6zOf1wUUh/oldovPweChyoAdMtUzgvCbJk1sYDJf++Nr0FeNW1RB1XG30=</D></RSAKeyValue>";
            RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
            byte[] cipherbytes;
            rsa.FromXmlString(privatekey);
            cipherbytes = rsa.Decrypt(Convert.FromBase64String(content), false);

            return Encoding.UTF8.GetString(cipherbytes);
        }

总结：加密解密算法博大精深，这里只是为了我们使用起来方便，有现成的算法（即使这样依然有人敢告诉我这个方法不知道怎么调用）供我们快速调用，对于秘钥本身这里不做过多探讨了，有兴趣的我们可以过后研究交流。鄙人也是初涉加密解密领域，各种不足，各位看官轻喷。