C#：一个增强的TcpClient（六）数据加密

using System;using System.IO;using System.Security.Cryptography;using System.Text;namespace Splash.Net.Sockets{       /// <summary>    /// 实现传送数据的加解密    /// </summary>    public partial class TcpClientPlus    {        /// <summary>        /// 哈希算法的密钥        /// </summary>        private const String _hmackey = "昨夜星辰昨夜风，画楼西畔桂堂东。身无彩凤双飞翼，心有灵犀一点通。";        /// <summary>        /// AES对称算法的托管实现        /// </summary>        protected AesManaged _aes;        /// <summary>        /// 加密密钥字段        /// </summary>        private String _secretKey;        /// <summary>        /// 加密密钥属性        /// </summary>        public String SecretKey        {            get { return _secretKey; }            set            {                _secretKey = value;                if (String.IsNullOrEmpty(value))                {   // 关闭加密传输模块                    SecurityClose();                  }                else                {                    if (_aes == null) _aes = new AesManaged();                    // 更新加密密钥（256位）                    using (SHA256Managed sha = new SHA256Managed())                    {                        _aes.Key = sha.ComputeHash(Encoding.UTF8.GetBytes(value + _salt));                        sha.Clear();    // 清除敏感数据                    }                    // 更新初始向量（128位）                    using (HMACMD5 hmacmd5 = new HMACMD5(Encoding.UTF8.GetBytes(_hmackey)))                    {                        _aes.IV = hmacmd5.ComputeHash(Encoding.UTF8.GetBytes(_salt));                        hmacmd5.Clear();    // 清除敏感数据                    }                }            }        }        /// <summary>        /// 最短密码佐料长度        /// </summary>        public const Int32 MinSaltLength = 16;        /// <summary>        /// 密码佐料字段        /// </summary>        private String _salt = "雄关漫道真如铁，而今迈步从头越。从头越，苍山如海，残阳如血。";        /// <summary>        /// 密码佐料属性        /// </summary>        public String Salt        {            get { return _salt; }            set            {   // 要求Salt的长度大于16个字符                if (!String.IsNullOrEmpty(value) && value.Length >= MinSaltLength)                {                    _salt = value;                    if (!String.IsNullOrEmpty(_secretKey))                    {   // 更新加密密钥（256位）                        using (SHA256Managed sha = new SHA256Managed())                        {                            _aes.Key = sha.ComputeHash(Encoding.UTF8.GetBytes(_secretKey + value));                            sha.Clear();    // 清除敏感数据                        }                        // 更新初始向量（128位）                        using (HMACMD5 hmacmd5 = new HMACMD5(Encoding.UTF8.GetBytes(_hmackey)))                        {                            _aes.IV = hmacmd5.ComputeHash(Encoding.UTF8.GetBytes(value));                            hmacmd5.Clear();    // 清除敏感数据                        }                    }                }            }        }        /// <summary>        /// 加密数据        /// </summary>        /// <param name="buffer">原始数据</param>        /// <param name="offset">字节偏移量</param>        /// <param name="count">要写入当前流的字节数</param>        /// <returns>加密后的数据</returns>                private Byte[] Encrypt(Byte[] buffer, Int32 offset, Int32 count)        {            using(MemoryStream ms = new MemoryStream())            {                using (CryptoStream cs = new CryptoStream(ms, _aes.CreateEncryptor(), CryptoStreamMode.Write))                {                    cs.Write(buffer, offset, count);                    cs.Close();                    return ms.ToArray();                }            }        }        /// <summary>        /// 解密数据        /// </summary>        /// <param name="buffer">原始数据</param>        /// <param name="offset">字节偏移量</param>        /// <param name="count">要写入当前流的字节数</param>        /// <returns>解密后的数据</returns>        private Byte[] Decrypt(Byte[] buffer, Int32 offset, Int32 count)        {            using (MemoryStream ms = new MemoryStream())            {                using (CryptoStream cs = new CryptoStream(ms, _aes.CreateDecryptor(), CryptoStreamMode.Write))                {                    cs.Write(buffer, offset, count);                    cs.Close();                    return ms.ToArray();                }            }        }        /// <summary>        /// 关闭加密传输模块        /// </summary>        private void SecurityClose()        {            if (_aes != null)            {                _aes.Clear();    // 清除敏感数据                _aes.Dispose();  // 释放资源                _aes = null;            }        }    }}