I'm an encryption novice trying to pass some values back and forth between systems. I can encrypt the value, but can't seem to figure out how to decrypt on the other end. I've created a simple Windows Forms application using VB.NET. Trying to input a value and a key, encrypt and then decrypt to get the original value. Here's my code so far. Any help greatly appreciated. Thanks.

Imports System Imports System.IO Imports System.Security.Cryptography Imports System.Text

Public Class Form1

Private Sub btnEncode_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEncode.Click
    Dim hmacsha1 As New HMACSHA1(Encoding.ASCII.GetBytes(txtKey.Text))
    Dim hashValue As Byte() = hmacsha1.ComputeHash(Encoding.ASCII.GetBytes(txtValue.Text))
    txtResult.Text = BytesToHexString(hashValue)
    hmacsha1.Clear()
End Sub

Private Sub btnDecode_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDecode.Click
    '???
End Sub

Private Function BytesToHexString(ByVal bytes As Byte()) As String
    Dim output As String = String.Empty
    Dim i As Integer = 0
    Do While i < bytes.Length
        output += bytes(i).ToString("X2")
        i += 1
    Loop
    Return output
End Function

End Class