C#简单的加密类实例

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
     }