Coldcard Firmware Update Mandates Physical Randomness for Seed Generation

CoinKite, the maker of the Coldcard Bitcoin hardware wallet, has released new standard firmware to address a security flaw in seed generation. The updated firmware, version 5.6.1 for Mk4 and Mk5 devices and 1.5.1Q for Q devices, requires users to add physical randomness whenever they generate a seed.

This means that owners who generate a seed after installing the fixed release can use the hardened process, which combines fresh device entropy with one required human input source: at least 65 key presses made at unpredictable intervals, or 50 rolls of a physical six-sided die, or 128 physical coin flips.

For owners still relying on a seed produced by affected firmware, Coinkite advises generating another seed and transferring the funds unless that wallet meets the dice-roll exception. The company has also provided migration guidance for affected users to generate a new seed, verify its backup and wallet fingerprint, confirm a receiving address on the device, send a small test transaction, and then transfer every balance tied to the old seed.