Query String Encryption & Decryption Technique in ASP.Net 3.5

In cryptography, encryption is the process of transforming information (referred to as plaintext) using an algorithm (called cipher) to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key.

The result of the process is encrypted information (in cryptography, referred to as cipher text). In many contexts, the word encryption also implicitly refers to the reverse process, decryption (e.g. "software for encryption" can typically also perform decryption), to make the encrypted information readable again (i.e. to make it unencrypted).

User Define Key for Encryption & Decryption:

private static string EncryptionKey = "!#853g`de";
private static byte[] key = { };
private static byte[] IV = { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };

Encryption Technique:

public string Encrypt(string Input)
        {
          try
           {
                key = System.Text.Encoding.UTF8.GetBytes(EncryptionKey.Substring(0, 8));
                DESCryptoServiceProvider des = new DESCryptoServiceProvider();
                Byte[] inputByteArray = Encoding.UTF8.GetBytes(Input);
                MemoryStream ms = new MemoryStream();
                CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(key, IV), CryptoStreamMode.Write);
                cs.Write(inputByteArray, 0, inputByteArray.Length);
                cs.FlushFinalBlock();
                return Convert.ToBase64String(ms.ToArray());
          }
         catch (Exception ex)
         {
           return "";
         }
       }

Decryption Technique :

public string Decrypt(string Input)
        {
            Byte[] inputByteArray = new Byte[Input.Length];

            try
            {
                key = System.Text.Encoding.UTF8.GetBytes(EncryptionKey.Substring(0, 8));
                DESCryptoServiceProvider des = new DESCryptoServiceProvider();
                inputByteArray = Convert.FromBase64String(Input);
                MemoryStream ms = new MemoryStream();
                CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(key, IV), CryptoStreamMode.Write);
                cs.Write(inputByteArray, 0, inputByteArray.Length);
                cs.FlushFinalBlock();
                Encoding encoding = Encoding.UTF8;
                return encoding.GetString(ms.ToArray());
            }
            catch (Exception ex)
            {
                return "";
            }
        }