COLDCARD MAKES THE DICE ROLLS CHECKABLE — ‘TREAT EVERY RELEASE AS CRITICAL’ — AND THE OLD SEEDS STILL HAVE TO GO
Trust turned into arithmetic: the device now shows its half of the seed, and a public script lets you recompute the rest yourself.
After this summer’s seed-generation failure, Coldcard is rebuilding trust the only way that counts in this business: by making the math checkable. The new firmware shows the full 256-bit device-generated input as 24 words BEFORE your dice rolls or coin flips get mixed in, and ships a public-domain script that recomputes the final seed offline — your rolls, their words, one answer, no trust required. The rest of the release reads like a security audit emptying its findings: a dozen boundary fixes across USB, transaction checking, and firmware handling, with a dozen outside researchers credited by name. The vendor’s own guidance for the road ahead is blunt — treat every firmware release as a critical update. And the sharp edge stays sharp: if your seed was generated on affected firmware between 2021 and July 2026, this update does not rescue it. New seed on fixed firmware, move the funds. Their words: upgrading alone is not sufficient. Same week Trezor’s customer database leak hit 80,000 people, the other hardware lesson lands too — the failures keep coming from everywhere except the one place users can now check themselves.
KEY RECEIPTS
Firmware 5.6.2 (Mk4/Mk5) and 1.5.2Q (Q), released Sept 4 (Coinkite blog, the primary).
View TRNG Words: displays the full 256-bit device-generated input as 24 BIP-39 words before user entropy is mixed in — visibility that was inadvertently missing from 5.6.1.
verify_seed_mix.py: public-domain, dependency-free, recomputes the final seed offline from the displayed words plus your full dice-roll or coin-flip sequence. Run it only on a trusted offline machine; prove the math on a throwaway seed, then generate a fresh unrecorded one for real funds.
Every new seed still requires user entropy: 65+ keypresses, 50+ dice rolls, or 128+ coin flips.
Vendor guidance, verbatim intent: treat every applicable firmware release as a critical update and upgrade promptly.
Hardening highlights: authenticated-encryption USB protocol, an out-of-bounds memory fix reachable from a compromised USB host, rejected malformed PSBTs and Virtual Disk files, duress-wallet and PIN-boundary fixes.
THE STANDING WARNING: seeds generated on affected firmware from 2021 through July 2026 must be REPLACED — new seed on fixed firmware, migrate the funds. Upgrading alone is not sufficient (Coldcard seed-generation advisory).
Related: Trezor’s leak grows to ~80,000 buyers.
View TRNG Words: displays the full 256-bit device-generated input as 24 BIP-39 words before user entropy is mixed in — visibility that was inadvertently missing from 5.6.1.
verify_seed_mix.py: public-domain, dependency-free, recomputes the final seed offline from the displayed words plus your full dice-roll or coin-flip sequence. Run it only on a trusted offline machine; prove the math on a throwaway seed, then generate a fresh unrecorded one for real funds.
Every new seed still requires user entropy: 65+ keypresses, 50+ dice rolls, or 128+ coin flips.
Vendor guidance, verbatim intent: treat every applicable firmware release as a critical update and upgrade promptly.
Hardening highlights: authenticated-encryption USB protocol, an out-of-bounds memory fix reachable from a compromised USB host, rejected malformed PSBTs and Virtual Disk files, duress-wallet and PIN-boundary fixes.
THE STANDING WARNING: seeds generated on affected firmware from 2021 through July 2026 must be REPLACED — new seed on fixed firmware, migrate the funds. Upgrading alone is not sufficient (Coldcard seed-generation advisory).
Related: Trezor’s leak grows to ~80,000 buyers.
The math is checkable now. The old seeds still are not safe.
Tick tock. Next block.
Tick tock. Next block.
Coinkite blog (primary) · Fri Sep 4 2026