Cyber Security

TOTP (Time-Based One-Time Password)

The Time-based One-Time Password algorithm (TOTP) is an extension of the HMAC-based One-time Password algorithm (HOTP) generating a one-time password by instead taking uniqueness from the current time. It has been adopted as Internet Engineering Task Force standard RFC 6238, is the cornerstone of Initiative For Open Authentication (OATH), and is used in a number of two-factor authentication systems.

Because of latency, both network and human, and unsynchronised clocks, the one-time password must validate over a range of times between the authenticator and the authenticated. Here, time is downsampled into larger durations (e.g., 30 seconds) to allow for validity between the parties. However, as with HOTP the decreased uniqueness requires additional countermeasures, such as rate limiting.

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