Roost — keyless HSM hardware
Roost is a 2U rack signing appliance. Three voting chips from three different manufacturers sign as a 2-of-3 quorum, a separate monitor watches every request, and each key comes from the silicon itself at power-up. Nothing is stored.
Built to the requirements of FIPS 140-3 and KCMVP, it is protected in layers: an outer steel shell with tamper seals, security screws and a lid switch; an inner enclosure sealed with a detection mesh on all six faces; and instant erasure on detection, together with temperature and voltage defenses.
- 2U 19-inch rack · 436 × 400 × 88 mm
- 3 voters from 3 manufacturers + 1 monitor · 2-of-3 quorum
- PUF keyless: keys are regenerated at power-up and never stored
- Sealed tamper-sensing enclosure · closed network, on-premises
Two of three must agree. The fourth only watches.
A signature leaves Roost only when at least two of the three voting chips produce it for the same request. A fourth device stands beside them and signs nothing.
One fails, signing continues
If a voter stops, the other two still make a quorum, and signing goes on until the unit is replaced.
One is compromised, nothing is signed
A single voter can never reach the quorum alone. Whoever takes over one chip still holds only one of the two signatures required.
The monitor does not sign
The monitor is a separate device with no signing key. It records every request, detects anomalies and blocks a request before it reaches the voters.
Flaws come by manufacturer, so the voters come from three.
Chips from the same company share a boot ROM, a bitstream format and a toolchain. A flaw in any of them reaches every chip in that line at once, as it did in 2020 when the bitstream encryption of an entire FPGA family was broken. So each voter in Roost is a chip from a different manufacturer.
- AMD Zynq UltraScale+
- Lattice MachXO3D
- Microchip PolarFire
If one chip, or a whole manufacturer's line, is broken, that is one vote. Roost needs two.
The key is not stored. It is regenerated.
Every voter carries a PUF, a circuit that reads the microscopic manufacturing variation of its own silicon. At power-up it regenerates the same key from that variation, and when power goes the key goes with it. There is no key file, no fuse and no backup to copy, so a powered-off Roost holds nothing to extract.
Tamper protection
Roost is built as two enclosures. The inner one is sealed and sensed on all six sides, and the power supply sits outside it.
Sealed sensing enclosure
A detection mesh lines all six faces of the inner enclosure, which is sealed shut. Heat leaves the inner enclosure by conduction through its walls, so it has no vent to reach through.
Opened means erased
Cutting, drilling or opening the enclosure erases the values needed to regenerate each PUF key, so that key can never be produced again. Erasure happens even with the power off, and signing stops.
Temperature and voltage guarded
Every chip has its own temperature sensor, every power rail is watched, and voltage glitches and clock anomalies are detected. Anything outside the safe range is treated as an attack: Roost stops signing and erases.
Watched even when off
A separate monitor board inside the mesh watches the lid and base switches, the cable entries and light, all the time. On battery it senses, records and erases even while the unit is off, and if the battery runs out the unit ends up erased, never open. Every detection and erasure is kept as a tamper-evident chain record.
Closed network, on-premises
Roost runs inside your network with no outbound connection, in your rack, your server room or your air-gapped site.
Roost complies with the requirements of FIPS 140-3, KCMVP and the CRA. How each standard applies