C#

Google Authenticator Algorithm

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Example code implementing the Google Authenticator algorithm. C#

//  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.

string secretBase32 = "JBSWY3DPEHPK3PXP";

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

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