HMAC-Based and Time-Based One-Time Passwords.

one-time-password

A One-Time Password (OTP) is a dynamic password used once in conjunction with an account's usual password, a for the purpose of two-factor authentication.

It can be based on a counter (HOTP) or a timestamp (TOTP). This module provides both methods.

Mobile authenticator applications will typically require a TOTP secret. They are most commonly provided as QR codes to scan. This library can generate a URI that can be used by a QR Code generator.