DES 加密解密字符串

        /// <summary>
        /// 字符串如果操过指定长度则将超出的部分用指定字符串代替
        /// </summary>
        /// <param name="p_SrcString">要检查的字符串</param>
        /// <param name="p_Length">指定长度</param>
        /// <param name="p_TailString">用于替换的字符串</param>
        /// <returns>截取后的字符串</returns>
        private static string GetSubString(string p_SrcString, int p_Length, string p_TailString)
        {
            return GetSubString(p_SrcString, 0, p_Length, p_TailString);
        }
        /// <summary>
        /// 取指定长度的字符串
        /// </summary>
        /// <param name="p_SrcString">要检查的字符串</param>
        /// <param name="p_StartIndex">起始位置</param>
        /// <param name="p_Length">指定长度</param>
        /// <param name="p_TailString">用于替换的字符串</param>
        /// <returns>截取后的字符串</returns>
        private static string GetSubString(string p_SrcString, int p_StartIndex, int p_Length, string p_TailString)
        {
            string myResult = p_SrcString;

            Byte[] bComments = Encoding.UTF8.GetBytes(p_SrcString);
            foreach (char c in Encoding.UTF8.GetChars(bComments))
            { //当是日文或韩文时(注:中文的范围:\u4e00 - \u9fa5, 日文在\u0800 - \u4e00, 韩文为\xAC00-\xD7A3)
                if ((c > '\u0800' && c < '\u4e00') || (c > '\xAC00' && c < '\xD7A3'))
                {
                    //if (System.Text.RegularExpressions.Regex.IsMatch(p_SrcString, "[\u0800-\u4e00]+") || System.Text.RegularExpressions.Regex.IsMatch(p_SrcString, "[\xAC00-\xD7A3]+"))
                    //当截取的起始位置超出字段串长度时
                    if (p_StartIndex >= p_SrcString.Length)
                        return "";
                    else
                        return p_SrcString.Substring(p_StartIndex,
                            ((p_Length + p_StartIndex) > p_SrcString.Length) ? (p_SrcString.Length - p_StartIndex) : p_Length);
                }
            }

            if (p_Length >= 0)
            {
                byte[] bsSrcString = Encoding.Default.GetBytes(p_SrcString);

                //当字符串长度大于起始位置
                if (bsSrcString.Length > p_StartIndex)
                {
                    int p_EndIndex = bsSrcString.Length;

                    //当要截取的长度在字符串的有效长度范围内
                    if (bsSrcString.Length > (p_StartIndex + p_Length))
                    {
                        p_EndIndex = p_Length + p_StartIndex;
                    }
                    else
                    { //当不在有效范围内时,只取到字符串的结尾
                        p_Length = bsSrcString.Length - p_StartIndex;
                        p_TailString = "";
                    }

                    int nRealLength = p_Length;
                    int[] anResultFlag = new int[p_Length];
                    byte[] bsResult = null;

                    int nFlag = 0;
                    for (int i = p_StartIndex; i < p_EndIndex; i++)
                    {
                        if (bsSrcString[i] > 127)
                        {
                            nFlag++;
                            if (nFlag == 3)
                                nFlag = 1;
                        }
                        else
                            nFlag = 0;

                        anResultFlag[i] = nFlag;
                    }

                    if ((bsSrcString[p_EndIndex - 1] > 127) && (anResultFlag[p_Length - 1] == 1))
                        nRealLength = p_Length + 1;

                    bsResult = new byte[nRealLength];

                    Array.Copy(bsSrcString, p_StartIndex, bsResult, 0, nRealLength);

                    myResult = Encoding.Default.GetString(bsResult);
                    myResult = myResult + p_TailString;
                }
            }

            return myResult;
        }

        //默认**向量
        private static readonly byte[] Keys = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };

       
        /// <summary>
        /// DES加密字符串
        /// </summary>
        /// <param name="encryptString">待加密的字符串</param>
        /// <param name="encryptKey">加***,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 DESEncode(string encryptString, string encryptKey)
        {
            encryptKey = GetSubString(encryptKey, 8, "");
            encryptKey = encryptKey.PadRight(8, ' ');
            byte[] rgbKey = Encoding.UTF8.GetBytes(encryptKey.Substring(0, 8));
            byte[] rgbIV = Encoding.UTF8.GetBytes(encryptKey.Substring(0, 8));
            byte[] inputByteArray = Encoding.UTF8.GetBytes(encryptString);
            DESCryptoServiceProvider dCSP = new DESCryptoServiceProvider();
            dCSP.Mode = CipherMode.ECB;
            dCSP.Padding = PaddingMode.PKCS7;
            MemoryStream mStream = new MemoryStream();
            CryptoStream cStream = new CryptoStream(mStream, dCSP.CreateEncryptor(rgbKey, rgbIV), CryptoStreamMode.Write);
            cStream.Write(inputByteArray, 0, inputByteArray.Length);
            cStream.FlushFinalBlock();
            return Convert.ToBase64String(mStream.ToArray());
        }

        /// <summary>
        /// DES加密字符串
        /// </summary>
        /// <param name="encryptString">待加密的字符串</param>
        /// <param name="encryptKey">加***,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 DESEncode(string encryptString, string encryptKey, Encoding encoding)
        {
            encryptKey = GetSubString(encryptKey, 8, "");
            encryptKey = encryptKey.PadRight(8, ' ');
            byte[] rgbKey = encoding.GetBytes(encryptKey.Substring(0, 8));
            byte[] rgbIV = encoding.GetBytes(encryptKey.Substring(0, 8));
            byte[] inputByteArray = encoding.GetBytes(encryptString);
            DESCryptoServiceProvider dCSP = new DESCryptoServiceProvider();
            dCSP.Mode = CipherMode.ECB;
            dCSP.Padding = PaddingMode.PKCS7;
            MemoryStream mStream = new MemoryStream();
            CryptoStream cStream = new CryptoStream(mStream, dCSP.CreateEncryptor(rgbKey, rgbIV), CryptoStreamMode.Write);
            cStream.Write(inputByteArray, 0, inputByteArray.Length);
            cStream.FlushFinalBlock();
            return Convert.ToBase64String(mStream.ToArray());
        }

        /// <summary>
        /// DES解密字符串
        /// </summary>
        /// <param name="decryptString">待解密的字符串</param>
        /// <param name="decryptKey">解***,要求为8位,和加***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 DESDecode(string decryptString, string decryptKey)
        {
            try
            {
                decryptKey = GetSubString(decryptKey, 8, "");
                decryptKey = decryptKey.PadRight(8, ' ');
                byte[] rgbKey = Encoding.UTF8.GetBytes(decryptKey);
                byte[] rgbIV = Encoding.UTF8.GetBytes(decryptKey);
                byte[] inputByteArray = Convert.FromBase64String(decryptString);
                DESCryptoServiceProvider DCSP = new DESCryptoServiceProvider();
                DCSP.Mode = CipherMode.ECB;
                DCSP.Padding = PaddingMode.PKCS7;
                MemoryStream mStream = new MemoryStream();
                CryptoStream cStream = new CryptoStream(mStream, DCSP.CreateDecryptor(rgbKey, rgbIV), CryptoStreamMode.Write);
                cStream.Write(inputByteArray, 0, inputByteArray.Length);
                cStream.FlushFinalBlock();
                return Encoding.UTF8.GetString(mStream.ToArray());
            }
            catch
            {
                return "";
            }
        }

        /// <summary>
        /// DES解密字符串
        /// </summary>
        /// <param name="decryptString">待解密的字符串</param>
        /// <param name="decryptKey">解***,要求为8位,和加***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 DESDecode(string decryptString, string decryptKey, Encoding encoding)
        {
            try
            {
                decryptKey = GetSubString(decryptKey, 8, "");
                decryptKey = decryptKey.PadRight(8, ' ');
                byte[] rgbKey = encoding.GetBytes(decryptKey);
                byte[] rgbIV = encoding.GetBytes(decryptKey);
                byte[] inputByteArray = Convert.FromBase64String(decryptString);
                DESCryptoServiceProvider DCSP = new DESCryptoServiceProvider();
                DCSP.Mode = CipherMode.ECB;
                DCSP.Padding = PaddingMode.PKCS7;
                MemoryStream mStream = new MemoryStream();
                CryptoStream cStream = new CryptoStream(mStream, DCSP.CreateDecryptor(rgbKey, rgbIV), CryptoStreamMode.Write);
                cStream.Write(inputByteArray, 0, inputByteArray.Length);
                cStream.FlushFinalBlock();
                return encoding.GetString(mStream.ToArray());
            }
            catch
            {
                return "";
            }
        }