An open and fully auditable hardware security key. Copper for the board, Rust for the firmware.
PatinaKey is a USB security key I'm designing from scratch, fully open : from the schematic all the way down to the silicon.
The name comes from two kinds of oxidation. Just as rust is the oxidation of iron, a patina is the oxidation of copper. A metaphor for the deep link between our physical medium (the copper board) and our memory-safe software (the Rust firmware).
The goal: a transparent root of trust, with no black boxes : reproducible and verifiable by anyone.
| Block | Choice | Why |
|---|---|---|
| Secure element | TROPIC01 (Tropic Square) | The first truly open-source, auditable secure element. Anti-brute-force PIN (MAC-and-Destroy), TRNG, PUF. |
| Microcontroller | STM32U545 | Secure Cortex-M33, full-speed USB, very power-efficient. |
| Firmware | Rust 🦀 | Memory safety by design. The right tool for security code. |
| Interface | USB-A gold fingers | The board is the plug. ENIG finish + 30° bevel. |
| Interaction | Touch + LED | Confirm an action with a single touch, no moving parts. |
| PCB | 4 layers, 49.3 × 18.6 mm | Clean ground plane, capped vias under the chips. |
| Repo | Contents |
|---|---|
hardware |
Altium sources, Gerbers, BOM, renders, manufacturing notes. |
firmware |
The Rust firmware (work in progress). |
- ✅ Schematic & 4-layer PCB routing
- ✅ Clean DRC + manufacturing files
- 🔶 First prototypes on order (JLCPCB)
- ⬜ Rust firmware
- 💡 v2: on-device screen + PIN entry
Personal open-source project · crafted with copper and rust, 2026 · patinakey.fr
