COLDIRON OS

Offline by design. Sovereign by default.

STATUS: v0.3.0 released — first product release

The weak point of Bitcoin self-custody is the moment your keys touch a machine that was ever online. COLDIRON OS turns any computer into the cold wallet: a hardened Linux distribution that boots from a USB stick, runs entirely from RAM, and ships a kernel with no network drivers at all. There is nothing to connect, nothing to compromise, nothing to trust — every line of it is in the open and builds reproducibly.

🔌 Networkless kernel

No network device drivers, no loadable modules. The kernel cannot reach a network even in theory.

🎲 Dice-seed wallet

Generate BIP39 seeds from physical dice rolls — the computer never creates your randomness. BIP84 self-check included.

🔐 Encrypted vault USB

LUKS2 + age double encryption for PSBTs, descriptors and optional seed backups.

🧾 Verified & signed

Every binary GPG-verified against keys you import out-of-band. Signed, reproducible releases.

🧠 Runs from RAM

toram boot: power off and every trace is gone. No persistence, no logs, no history.

🕵️ Auditable

Built from source with live-build. Two machines produce a byte-identical ISO. No black boxes.

Download

Get the ISO and verify it before writing it to USB — verifying is part of using it:

sha256sum -c SHA256SUMS
gpg --keyserver keyserver.ubuntu.com --recv-keys 63EA0A22C16AD05182378B9B7F5397DF4477C2BD
gpg --verify SHA256SUMS.asc SHA256SUMS
sudo dd if=coldiron-os-0.3.0-amd64.iso of=/dev/sdX bs=4M status=progress

Release artifacts are GPG-signed with a one-shot project key (fingerprint 63EA 0A22 C16A D051 8237 8B9B 7F53 97DF 4477 C2BD) that was revoked immediately after signing — the signatures verify as "Good", the key shows as revoked by design, and the fingerprint is the trust anchor (see SIGNING.md). For the strongest guarantee, build the ISO yourself and compare hashes.

Releases on GitHub Source code

How it works

Two USB sticks. One boots COLDIRON (read-only, RAM-only). The other is an encrypted vault for your PSBTs and optional backups. You generate your seed with physical dice, write it on paper, and sign transactions in Sparrow Wallet — inside an operating system that provably has no network.

Read the honest security model in THREAT-MODEL.md before trusting it with anything valuable.