Recommended versions require device entropy and a user contribution
COLDCARD has published a flow map linked to the code for Mk4 and Mk5 from version 5.6.1, and for Q from version 1.5.1Q. The change log states that the visualisation was added on 3 September 2026.
To create a new seed, these versions combine fresh device entropy with a user-required method: at least 65 key presses with unpredictable timing, 50 rolls of a physical six-sided die, or 128 physical coin flips. The advanced Dice Rolls Only path remains separate. For a wallet whose loss would cause material harm to its owner, Coldcard recommends a strong, unique BIP-39 passphrase, stored separately from the seed and tested during recovery before funds are deposited.
The firmware update corrects future generation but does not alter or repair an existing seed. A seed created on affected firmware requires migration, except where at least 50 fair, independent, private dice rolls were used and were never recorded or exposed. According to the notice, those rolls add at least 128 bits of entropy; 99 or more rolls provide about 256 bits. Version 4.2.0 is the last for Mk2 and Mk3 and can generate a corrected replacement seed.
The page reports limited independent checks: Shiny observed eight readings from the hardware random-number generator on Mk4 5.6.0; other reviewers examined the removal of the software fallback and build checks. PortlandHODL rebuilt the Mk4/Mk5 5.6.0 firmware and traced the dice path. Coldcard states that these checks do not constitute a complete audit of every binary and that the formal technical postmortem remains under way.
