B4X

Google Authenticator Algorithm

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Example code implementing the Google Authenticator algorithm. B4X

'  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 ChilkatCrypt2
crypt.Initialize("crypt")
Dim otp As String = crypt.Totp(secretBase32, "base32", "0", "", 30, 6, -1, "sha1")

Log("6-digit decimal token = " & otp)