求一种加密算法
我要的效果是这样的，大批量数据，加密后是固定长度（最好能小于50位的），并且能被解密的算法。

[解决办法]
我想到的就是位移下加密，再位移下解密
[解决办法]

C# code

 /// <summary>        /// 创建Key        /// </summary>        /// <returns></returns>        public static string GenerateKey()        {            DESCryptoServiceProvider desCrypto = (DESCryptoServiceProvider)DESCryptoServiceProvider.Create();            return ASCIIEncoding.ASCII.GetString(desCrypto.Key);        }        /// <summary>        /// MD5加密        /// </summary>        /// <param name="pToEncrypt"></param>        /// <param name="sKey"></param>        /// <returns></returns>        public static string MD5Encrypt(string pToEncrypt, string sKey)        {            DESCryptoServiceProvider des = new DESCryptoServiceProvider();            byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);            des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);            des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);            MemoryStream ms = new MemoryStream();            CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);            cs.Write(inputByteArray, 0, inputByteArray.Length);            cs.FlushFinalBlock();            StringBuilder ret = new StringBuilder();            foreach (byte b in ms.ToArray())            {                ret.AppendFormat("{0:X2}", b);            }            ret.ToString();            return ret.ToString();        }        /// <summary>        /// MD5解密        /// </summary>        /// <param name="pToDecrypt"></param>        /// <param name="sKey"></param>        /// <returns></returns>        public static string MD5Decrypt(string pToDecrypt, string sKey)        {            DESCryptoServiceProvider des = new DESCryptoServiceProvider();            byte[] inputByteArray = new byte[pToDecrypt.Length / 2];            for (int x = 0; x < pToDecrypt.Length / 2; x++)            {                int i = (Convert.ToInt32(pToDecrypt.Substring(x * 2, 2), 16));                inputByteArray[x] = (byte)i;            }            des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);            des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);            MemoryStream ms = new MemoryStream();            CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);            cs.Write(inputByteArray, 0, inputByteArray.Length);            cs.FlushFinalBlock();            StringBuilder ret = new StringBuilder();            return System.Text.Encoding.Default.GetString(ms.ToArray());        }
[解决办法]
你觉得可能吗？


密文为固定长度，明文长度不确定，要解密的，没有这样的算法，也没有这样的压缩方法，
建议你了解下加密，解密，压缩

我要的效果是这样的，大批量数据，加密后是固定长度（最好能小于50位的），并且能被解密的算法。
因为MD5无法被解密，DES的话长度也不能固定