Implements an interface to access Google Authenticator functionality
Supports both counter-based (HOTP) and time-based (TOTP) authentication mechanisms
Is loosely based on other publicly available implementations: 1) https://github.com/PHPGangsta/GoogleAuthenticator by Michael Kliewe 2) http://dendory.net/twofactors by Patrick Lambert
This class uses base32 encoding and decoding by Bryan Ruiz
Usage:
1) When user is registered or enrolled into 2 factor authentication, generate a unique key for them with getNewKey()
That key should be stored as it will be used every time user attempts to authenticate
2) Call getQrCodeUrl() to show them a QR code to set up their authenticator app
If the QR code cannot be used or is not desired, ask user to enter the generated key into their app manually
It is possible to set up two kind of accounts in the app - counter- and time-based
3) Once user's app is initialised, ask for that value when user needs to be authenticated and call
verifyCode() supplying the value provided.
The client must be set into a proper mode - counter or time-based (depending on what QR code user has been given)
Could be freely used and distributed as long as attributed to Yuriy Akopov (akopov@hotmail.co.uk)
