public static class EncryptAndDecrypt
     {
         //加密
         public static string Encrypt(string input)
         {
             // 盐值
             string saltValue = "saltValue";
             // 密码值
             string pwdValue = "pwdValue";
             byte[] data = System.Text.UTF8Encoding.UTF8.GetBytes(input);
             byte[] salt = System.Text.UTF8Encoding.UTF8.GetBytes(saltValue);
             // AesManaged - 高级加密标准(AES) 对称算法的管理类
             System.Security.Cryptography.AesManaged aes = new System.Security.Cryptography.AesManaged();
             // Rfc2898DeriveBytes - 通过使用基于 HMACSHA1 的伪随机数生成器，实现基于密码的密钥派生功能 (PBKDF2 - 一种基于密码的密钥派生函数)
             // 通过 密码 和 salt 派生密钥
             System.Security.Cryptography.Rfc2898DeriveBytes rfc = new System.Security.Cryptography.Rfc2898DeriveBytes(pwdValue, salt);
             /**/
             /*
          * AesManaged.BlockSize - 加密操作的块大小（单位：bit）
          * AesManaged.LegalBlockSizes - 对称算法支持的块大小（单位：bit）
          * AesManaged.KeySize - 对称算法的密钥大小（单位：bit）
          * AesManaged.LegalKeySizes - 对称算法支持的密钥大小（单位：bit）
          * AesManaged.Key - 对称算法的密钥
          * AesManaged.IV - 对称算法的密钥大小
          * Rfc2898DeriveBytes.GetBytes(int 需要生成的伪随机密钥字节数) - 生成密钥
          */
             aes.BlockSize = aes.LegalBlockSizes[0].MaxSize;
             aes.KeySize = aes.LegalKeySizes[0].MaxSize;
             aes.Key = rfc.GetBytes(aes.KeySize / 8);
             aes.IV = rfc.GetBytes(aes.BlockSize / 8);
             // 用当前的 Key 属性和初始化向量 IV 创建对称加密器对象
             System.Security.Cryptography.ICryptoTransform encryptTransform = aes.CreateEncryptor();
             // 加密后的输出流
             System.IO.MemoryStream encryptStream = new System.IO.MemoryStream();
             // 将加密后的目标流（encryptStream）与加密转换（encryptTransform）相连接
             System.Security.Cryptography.CryptoStream encryptor = new System.Security.Cryptography.CryptoStream
                 (encryptStream, encryptTransform, System.Security.Cryptography.CryptoStreamMode.Write);
             // 将一个字节序列写入当前 CryptoStream （完成加密的过程）
             encryptor.Write(data, 0, data.Length);
             encryptor.Close();
             // 将加密后所得到的流转换成字节数组，再用Base64编码将其转换为字符串
             string encryptedString = Convert.ToBase64String(encryptStream.ToArray());
             return encryptedString;
         }

 
         #region silverlight密码解密
         /**/
         /// <summary>
         /// 解密数据
         /// </summary>
         /// <param name="input">加密后的字符串</param>
         /// <returns>加密前的字符串</returns>
         public static string Decrypt(string input)
         {
             // 盐值（与加密时设置的值一致）
             string saltValue = "saltValue";
             // 密码值（与加密时设置的值一致）
             string pwdValue = "pwdValue";
             byte[] encryptBytes = Convert.FromBase64String(input);
             byte[] salt = Encoding.UTF8.GetBytes(saltValue);
             System.Security.Cryptography.AesManaged aes = new System.Security.Cryptography.AesManaged();
             System.Security.Cryptography.Rfc2898DeriveBytes rfc = new System.Security.Cryptography.Rfc2898DeriveBytes(pwdValue, salt);
             aes.BlockSize = aes.LegalBlockSizes[0].MaxSize;
             aes.KeySize = aes.LegalKeySizes[0].MaxSize;
             aes.Key = rfc.GetBytes(aes.KeySize / 8);
             aes.IV = rfc.GetBytes(aes.BlockSize / 8);
             // 用当前的 Key 属性和初始化向量 IV 创建对称解密器对象
             System.Security.Cryptography.ICryptoTransform decryptTransform = aes.CreateDecryptor();
             // 解密后的输出流
             MemoryStream decryptStream = new MemoryStream();
             // 将解密后的目标流（decryptStream）与解密转换（decryptTransform）相连接
             System.Security.Cryptography.CryptoStream decryptor = new System.Security.Cryptography.CryptoStream(
                 decryptStream, decryptTransform, System.Security.Cryptography.CryptoStreamMode.Write);
             // 将一个字节序列写入当前 CryptoStream （完成解密的过程）
             decryptor.Write(encryptBytes, 0, encryptBytes.Length);
             decryptor.Close();
             // 将解密后所得到的流转换为字符串
             byte[] decryptBytes = decryptStream.ToArray();
             string decryptedString = UTF8Encoding.UTF8.GetString(decryptBytes, 0, decryptBytes.Length);
             return decryptedString;
         }
         #endregion
     }