Overview#
Google Authenticator is an
Authenticator that provides a
soft token that implements two-step verification services using the
Time-based One-time Password Algorithm (
TOTP) and
HMAC-based One-Time Password Algorithm (
HOTP), for
authenticating users of
mobile Device applications by
Google.
The service implements algorithms specified in RFC 6238 and RFC 4226.
Authenticator provides a six- to eight-digit one-time password which users MUST provide in addition to their username and password to log into Google services or other websites.
Previous versions of the Google Authenticator were open-sourced but subsequent releases are proprietary.
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