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TOTP and HOTP

Open Authentication → OTP → Add QR over USB and copy one otpauth:// QR image onto the temporary FAT12 drive. Read the account and parameters on the device, confirm, then eject the volume from the computer.

  • PNG or baseline JPEG; progressive JPEG and HEIC are unsupported.
  • At most 256 KiB and 1024 × 1024 pixels, with one relevant QR per image.
  • SHA1/SHA256/SHA512, 6/7/8 digits; TOTP periods from 15 to 300 seconds.
  • HOTP increments its persistent counter only after a physical confirmation.

Set the time for TOTP

Choose Settings → TOTP time → Sync over USB. Send the current Unix time through the temporary serial port using any terminal, or run:

uv run python tools/feuristic_time.py

The clock is retained while USB modes change, but is lost on power removal. Unsynchronised devices show a request to set the time instead of inventing a code. See time sync and the OTP URI profile.