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feuristic — custom firmware for Trezor Safe 3

feuristic firmware for Trezor Safe 3: FIDO2, OpenPGP, PIV, OTP and AES-GCM

feuristic replaces the wallet application on a Trezor Safe 3 with a USB security key, smart card and one-time password device. It runs on T2B1 and T3B1 hardware. Configuration and confirmations happen on the two buttons; standard clients handle authentication and cryptography.

Install feuristic Download firmware

Before you install

Installation erases the wallet and permanently removes original manufacturer attestation. feuristic is independent of Trezor Company and SatoshiLabs. Core workflows passed a physical T2B1/macOS campaign; T3B1 hardware and the complete acceptance matrix are still in progress. Keep a second way to sign in to important accounts.

Five feuristic screens: lock screen, passkey approval, saved passkeys, a TOTP code and an encrypted backup QR code

What it supports

Function Interface Get started
Passkeys and security keys FIDO2 / WebAuthn, CTAP 2.1, U2F FIDO2 guide
OpenPGP signing and decryption OpenPGP Card 3.4, GnuPG OpenPGP guide
Certificates and authentication PIV, PC/SC, PKCS#11 clients PIV guide
One-time passwords TOTP / HOTP, QR image import OTP guide
Encryption and random bytes AES-256-GCM / ISO 7816 APDUs AES and RNG guide
Encrypted identity backup QR sequences, PNG/JPEG restore Backup guide

Install in three steps

  1. Check your model and download. Select the exact T2B1 or T3B1 .bin from Downloads, then verify its SHA-256 checksum.
  2. Open the bootloader and install. On a backed-up, disposable device, unlock once and select the downloaded file in Trezor Suite, or upload it with trezorctl. Confirm every request on the device. A firmware file is not copied onto the OTP import drive.
  3. Create a device PIN. Accept the third-party boot warning, choose English or French, set the PIN and follow the user guide.

Read the complete installation procedure before step 2. It explains the irreversible effects, exact button sequence and recovery path.

Interfaces and controls

feuristic USB modes: FIDO and smart card, serial time sync, and QR import

Normal operation exposes FIDO HID and a CCID smart-card reader. Time sync uses a temporary serial port; QR import uses a temporary FAT12 drive. These modes are exclusive and return to normal after completion.

  • Left: previous. Right: next. Both: confirm.
  • Hold left: back or refuse. Destructive actions require a held confirmation.
  • The device PIN protects storage. FIDO, OpenPGP and PIV credentials are separate.

Tested behavior and remaining work

The physical T2B1 report records verified signatures, AES-GCM, OTP imports, clock sync and persistence across updates. The acceptance register distinguishes these results from emulator tests and lists the remaining hardware work.

For implementation details, read the architecture, threat model and protocol references.