public static class Encryption
     {
         #region silverlight数据加密
         /**/
         /// <summary>
         /// 加密数据
         /// </summary>
         /// <param name="input">加密前的字符串</param>
         /// <returns>加密后的字符串</returns>
         public static string Encrypt(string input)
         {
             //定义的字符串
             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;
         }
         #endregion        #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 = System.Text.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
             System.IO.MemoryStream decryptStream = new System.IO.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 = System.Text.UTF8Encoding.UTF8.GetString(decryptBytes, 0, decryptBytes.Length);            return decryptedString;
         }
         #endregion    }
 
 
   (2)
 /// <summary>
     /// 加密解密辅助类
     /// </summary>
     public class EncrptHelp
     {
         /// <summary>
         /// 加密
         /// </summary>
         /// <param name="sText"></param>
         /// <returns></returns>
         public static string SimpleEncrpt(string sText)
         {
             byte[] btBuffer = System.Text.Encoding.UTF8.GetBytes(sText);
             for (int i = 0; i < btBuffer.Length; i++)
             {
                 btBuffer[i] = SwithByte(btBuffer[i]);
             }
             return System.Convert.ToBase64String(btBuffer);
         }        
         private static byte SwithByte(byte bSouce)
         {
             int bResult = bSouce;
             int bTemp1, bTemp2;
             int nStep = 6;
             byte bMark;
             int nCount = 0;
             int nWhileRange = 2;            for (int i = 0; i < 2; i++)
             {
                 while (nCount < nWhileRange)
                 {
                     bTemp1 = bResult & m_aryByteTable[nCount];
                     bTemp1 = bTemp1 << nStep;
                     bTemp2 = bResult & m_aryByteTable[nCount + nStep];
                     bTemp2 = bTemp2 >> nStep;
                     if (bTemp1 != 0)
                         bResult = bResult | bTemp1;
                     else
                     {
                         bMark = m_aryByteTableMark[nCount + nStep];
                         bResult = bResult & bMark | bTemp1;
                     }                    if (bTemp2 != 0)
                         bResult = bResult | bTemp2;
                     else
                     {
                         bMark = m_aryByteTableMark[nCount];
                         bResult = bResult & bMark | bTemp1;
                     }
                     nCount++;
                 }
                 nStep = 2;
                 nWhileRange = 4;
             }
             return (byte)bResult;
         }
         private readonly static byte[] m_aryByteTable = { 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80 };
         private readonly static byte[] m_aryByteTableMark = { 0xFE, 0xFD, 0xFB, 0xF7, 0xEF, 0xDF, 0xBF, 0x7F };        //        URL中的特殊字符 
         //有些符号在URL中是不能直接传递的,如果要在URL中传递这些特殊符号,那么就要使用他们的编码了。编码的格式为:%加字符的ASCII码,即一个百分号%,后面跟对应字符的ASCII(16进制)码值。例如 空格的编码值是"%20"。        //1. +  URL 中+号表示空格 %2B 
         //2. 空格 URL中的空格可以用+号或者编码 %20 
         //3. /  分隔目录和子目录 %2F  
         //4. ?  分隔实际的 URL 和参数 %3F  
         //5. % 指定特殊字符 %25  
         //6. # 表示书签 %23  
         //7. & URL 中指定的参数间的分隔符 %26  
         //8. = URL 中指定参数的值 %3D
         public static string UrlEncode(string sText)
         {
             return sText.Replace("+", "%2B").
                 Replace(" ", "%20").
                 Replace("/", "%2F").
                 Replace("?", "%3F").
                 Replace("%", "%25").
                 Replace("#", "%23").
                 Replace("&", "%26").
                 Replace("=", "%3D");
         }