Question

I need to create a keyed hash for a string of XML to send to a 3rd party. This is the code I am using but it is producing a different hash than the example that the 3rd party has sent me. I have been through all the tutorials I can find and re-read MSDN again and again. What am I doing wrong? Or should I suspect a problem at the other end?

Public Shared Function HashString(ByVal StringToHash As String) As String
    Dim myEncoder As New System.Text.UTF32Encoding
    Dim Key() As Byte = myEncoder.GetBytes(My.Settings.PortalHASH)
    Dim XML() As Byte = myEncoder.GetBytes(StringToHash)
    Dim myHMACSHA256 As New System.Security.Cryptography.HMACSHA256(Key)
    Dim HashCode As Byte() = myHMACSHA256.ComputeHash(XML)
    Return Convert.ToBase64String(HashCode)
End Function

It needs to be base-64 encoded, which is why I have the last line.

Thanks

Answer 1

(Read my comments)
If My.Settings.PortalHASH is the Base64 encoded key you need to do this:

Dim Key() As Byte = Convert.FromBase64String(My.Settings.PortalHASH)