(VB.NET) Google Authenticator Algorithm

Example code implementing the Google Authenticator algorithm.

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' This example assumes the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

' Generating TOTP Base32 Secret: 
' When you enable 2FA with a TOTP-based authenticator app, Google will provide you with a QR code
' that you can scan using the app. This QR code contains a TOTP base32 secret.
' You can also choose to view and copy the secret manually.

Dim secretBase32 As String = "JBSWY3DPEHPK3PXP"

' Do the following to calculate the 6-digit decimal Google authenticator token for a base32 secret,
' given the current system date/time.
Dim crypt As New Chilkat.Crypt2
Dim otp As String = crypt.Totp(secretBase32,"base32","0","",30,6,-1,"sha1")

Debug.WriteLine("6-digit decimal token = " & otp)