What IETF RFC 6238 TOTP Time-Based One-Time Password Algorithm - Time Step T Equals Floor of Unix Time Minus T0 Over X HMAC-SHA-1 Dynamic Truncation 30 Second Default Step Clock Drift Tolerance and Multi-Factor Authentication requires
IETF RFC 6238 specifies TOTP the Time-Based One-Time Password Algorithm extending HOTP RFC 4226 by replacing the event counter with a time-derived value computed as T equals the floor of current Unix time minus T0 divided by X where T0 defaults to zero the Unix epoch and X represents the time step in seconds with a default of thirty seconds, with security resting on HMAC-SHA-1 from RFC 2104 with permitted alternatives of HMAC-SHA-256 or HMAC-SHA-512 and the dynamic truncation process converting HMAC output into user-friendly numeric values, recommending a default time-step size of thirty seconds balancing security and usability, addressing clock drift by accepting OTPs from multiple time steps backward and forward, requiring rejection of duplicate submissions within a given time-step window, and providing the basis for authenticator apps and hardware tokens used in multi-factor authentication workflows.
Pillar: Workflow Automation · Authority: Internet Engineering Task Force (datatracker.ietf.org) · Version: 1.0.0 · Last updated:
Primary source: https://datatracker.ietf.org/doc/html/rfc6238
SHA-256 integrity: a580aeb377e53cd1c77cfd910d45909755897c6e09253a82e244a69704eb0981
Primary Citations — 8 traced to source
- RFC 6238 TOTP Time-Based One-Time Password Algorithm https://datatracker.ietf.org/doc/html/rfc6238
- Section 4 algorithm https://datatracker.ietf.org/doc/html/rfc6238#section-4
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