.net 密码加密 （可逆）

把用户登陆的密码加密了，为了能看到原始的密码，可以解密。 主要是防止有人知道数据库的用户名和密码用查询分析器进入数据库查看到密码

  没有用MD5, MD5是不能解密的。

 /// <summary>
        /// 加密
        /// </summary>
        /// <param name="rs"></param>
        /// <returns></returns>
        public static string  DESEncryptMethod(string rs)
        {
            byte[] desKey = new byte[] { 0x16, 0x09, 0x14, 0x15, 0x07, 0x01, 0x05, 0x08 };
            byte[] desIV = new byte[] { 0x16, 0x09, 0x14, 0x15, 0x07, 0x01, 0x05, 0x08 };

            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            try
            {
                byte[] inputByteArray = Encoding.Default.GetBytes(rs);
                //byte[] inputByteArray=Encoding.Unicode.GetBytes(rs);

                des.Key = desKey;  // ASCIIEncoding.ASCII.GetBytes(sKey);
                des.IV = desIV;   //ASCIIEncoding.ASCII.GetBytes(sKey);
                MemoryStream ms = new MemoryStream();
                CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(),
                 CryptoStreamMode.Write);
                //Write the byte array into the crypto stream
                //(It will end up in the memory stream)
                cs.Write(inputByteArray, 0, inputByteArray.Length);
                cs.FlushFinalBlock();

                //Get the data back from the memory stream, and into a string
                StringBuilder ret = new StringBuilder();
                foreach (byte b in ms.ToArray())
                {
                    //Format as hex
                    ret.AppendFormat("{0:X2}", b);
                }
                ret.ToString();
                return ret.ToString();
            }
            catch
            {
                return rs;
            }
            finally
            {
                des = null;
            }
        }
       
        /// <summary>
        /// 解密
        /// </summary>
        /// <param name="rs"></param>
        /// <returns></returns>
        public static string  DESDecryptMethod(string rs)   
        {
            byte[] desKey = new byte[] { 0x16, 0x09, 0x14, 0x15, 0x07, 0x01, 0x05, 0x08 };
            byte[] desIV = new byte[] { 0x16, 0x09, 0x14, 0x15, 0x07, 0x01, 0x05, 0x08 };

            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            try
            {
                //Put the input string into the byte array
                byte[] inputByteArray = new byte[rs.Length / 2];
                for (int x = 0; x < rs.Length / 2; x++)
                {
                    int i = (Convert.ToInt32(rs.Substring(x * 2, 2), 16));
                    inputByteArray[x] = (byte)i;
                }

                des.Key = desKey;   //ASCIIEncoding.ASCII.GetBytes(sKey);
                des.IV = desIV;    //ASCIIEncoding.ASCII.GetBytes(sKey);
                MemoryStream ms = new MemoryStream();
                CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
                //Flush the data through the crypto stream into the memory stream
                cs.Write(inputByteArray, 0, inputByteArray.Length);
                cs.FlushFinalBlock();

                //Get the decrypted data back from the memory stream
                StringBuilder ret = new StringBuilder();

                return System.Text.Encoding.Default.GetString(ms.ToArray());
            }
            catch
            {
                return rs;
            }
            finally
            {
                des = null;
            }
        }

可以直接拿来用。