simple encoding/decoding technique in ASP.net

Imports System
Imports Microsoft.VisualBasic
Imports System.IO
Imports System.Xml
Imports System.Text
Imports System.Security.Cryptography
 
 
Public Class EncryptDecrypt
    Private key() As Byte = {}
    Private IV() As Byte = {&H12, &H34, &H56, &H78, &H90, &HAB, &HCD, &HEF}
 
    Public Function Decrypt(ByVal stringToDecrypt As String, _
        ByVal sEncryptionKey As String) As String
        Dim inputByteArray(stringToDecrypt.Length) As Byte
        Try
            key = System.Text.Encoding.UTF8.GetBytes(Left(sEncryptionKey, 8))
            Dim des As New DESCryptoServiceProvider()
            inputByteArray = Convert.FromBase64String(stringToDecrypt)
            Dim ms As New MemoryStream()
            Dim cs As New CryptoStream(ms, des.CreateDecryptor(key, IV), _
                CryptoStreamMode.Write)
            cs.Write(inputByteArray, 0, inputByteArray.Length)
            cs.FlushFinalBlock()
            Dim encoding As System.Text.Encoding = System.Text.Encoding.UTF8
            Return encoding.GetString(ms.ToArray())
        Catch e As Exception
            Return e.Message
        End Try
    End Function
 
    Public Function Encrypt(ByVal stringToEncrypt As String, _
        ByVal SEncryptionKey As String) As String
        Try
            key = System.Text.Encoding.UTF8.GetBytes(Left(SEncryptionKey, 8))
            Dim des As New DESCryptoServiceProvider()
            Dim inputByteArray() As Byte = Encoding.UTF8.GetBytes( _
                stringToEncrypt)
            Dim ms As New MemoryStream()
            Dim cs As New CryptoStream(ms, des.CreateEncryptor(key, IV), _
                CryptoStreamMode.Write)
            cs.Write(inputByteArray, 0, inputByteArray.Length)
            cs.FlushFinalBlock()
            Return Convert.ToBase64String(ms.ToArray())
        Catch e As Exception
            Return e.Message
        End Try
    End Function
 
    Public Shared Function encryptQueryString(ByVal strQueryString As String) As String
        Dim oES As New ExtractAndSerialize.EncryptDecrypt()
        Return (oES.Encrypt(strQueryString, "!#$a54?3"))
    End Function
 
 
    Public Function decryptQueryString(ByVal strQueryString As String) As String
        Dim oES As New ExtractAndSerialize.EncryptDecrypt()
        Return (oES.Decrypt(strQueryString, "!#$a54?3"))
    End Function
 
 
End Class
                                              

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