EncryptHelper

    public class EncryptHelper
    {
        public static string EncryptMd5Str(string str)
        {
            MD5 md5Obj = MD5.Create();
            byte[] buffer = System.Text.Encoding.Default.GetBytes(str);
            byte[] Md5Buffer = md5Obj.ComputeHash(buffer);
            return BitConverter.ToString(Md5Buffer).Replace("-", "").ToLower();
        }
        /// <summary>
        /// 简单加密函数
        /// </summary>
        /// <param name="str">要加密的字符串</param>
        /// <returns>返回加密后的字符串</returns>
        /// 
        public string simple_Encode(string str)
        {
            string s = "";
            try
            {
                for (int i = 0; i < str.Length; i++)
                {
                    s += (char)(str[i] + 10 - 1 * 2);
                }
                return s;
            }
            catch
            {
                return str;
            }
        }
        
        /// <summary>
        /// 简单解密函数
        /// </summary>
        /// <param name="str">要解密的字符串</param>
        /// <returns>返回解密后的字符串</returns>
        /// 
        public string simple_Decode(string str)
        {
            string s = "";
            try
            {
                for (int i = 0; i < str.Length; i++)
                {
                    s += (char)(str[i] - 10 + 1 * 2);
                }
                return s;
            }
            catch
            {
                return str;
            }
        }

        //默认密钥向量
        private static byte[] Keys = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };
        
        /// <summary>
        /// 对称加密法加密函数
        /// </summary>
        /// <param name="encryptString">待加密的字符串</param>
        /// <param name="encryptKey">加密密钥,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 string symmetry_Encode(string encryptString, string encryptKey)
        {
            try
            {
                byte[] rgbKey = Encoding.UTF8.GetBytes(encryptKey.Substring(0, 8));
                byte[] rgbIV = Keys;
                byte[] inputByteArray = Encoding.UTF8.GetBytes(encryptString);
                DESCryptoServiceProvider dCSP = new DESCryptoServiceProvider();
                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());
            }
            catch
            {
                return encryptString;
            }
        }
       
        /// <summary>
        /// 对称加密法解密函数
        /// </summary>
        /// <param name="decryptString">待解密的字符串</param>
        /// <param name="decryptKey">解密密钥,要求为8位,和加密密钥相同</param>
        /// <returns>解密成功返回解密后的字符串，失败返源串</returns>

        public string symmetry_Decode(string decryptString, string decryptKey)
        {
            try
            {
                byte[] rgbKey = Encoding.UTF8.GetBytes(decryptKey);
                byte[] rgbIV = Keys;
                byte[] inputByteArray = Convert.FromBase64String(decryptString);
                DESCryptoServiceProvider DCSP = new DESCryptoServiceProvider();
                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 decryptString;
            }
        }

    }