TOTP 2FA Authenticator Generator

How Time-Based One-Time Passwords (TOTP) Work

TOTP is an open IETF computer security standard (RFC 6238) that computes a one-time passcode from a shared secret key and the current Unix time. It is an extension of the HMAC-based One-Time Password algorithm (HOTP, RFC 4226).

The Mathematical Formula:

1. Time Counter: $T = \lfloor (\text{Current Unix Time} - T_0) / X \rfloor$, where $X$ is the standard step interval (typically 30 seconds).
2. HMAC Computation: Compute an HMAC-SHA1 signature using the shared Base32 secret key on the 8-byte big-endian time counter.
3. Dynamic Truncation: Extract a 4-byte dynamic binary code from the HMAC output based on the low-order 4 bits of the last byte.
4. Modulo Reduction: Compute $\text{Code} = \text{BinaryCode} \pmod{10^6}$ to yield the familiar 6-digit numeric token.

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How to Use

1. Enter Base32 Secret: Type or paste your 2FA secret key (e.g., JBSWY3DPEHPK3PXP). You can also click 🎲 Generate Random Secret if you are configuring a new user profile.
2. Watch Live Token: The active passcode updates automatically with a visual progress bar indicating time remaining in the current 30-second window.
3. Copy with One Click: Click the large token box to copy the active code directly to your clipboard.
4. Verify Codes: Use the verification section to test codes against clock drift (±1 time step).