Coldcard Firmware 5.6.1 Forces User Entropy Into Every New Seed After $100M Exploit

Coinkite has released new Coldcard firmware that forces users to provide their own randomness when generating new wallet seeds. Coinkite, the company behind Coldcard, has shipped a firmware update that will not generate a new wallet seed until the owner supplies randomness by hand. That means at least 50 dice rolls, 128 coin flips, or 65 timed key presses, three weeks after a defect in its random number generator opened customer funds to attackers. Coldcard’s two device lines run separate firmware tracks, so the release carries two numbers, 5.6.1 for the Mk4 and Mk5, and 1.5.1Q for the Q, the larger model with a keyboard and QR scanning. Boot Check Targets the Defect Coinkite stated that the input is added on top of device randomness from the STM32 TRNG and both secure elements. Coldcard was built to draw seed entropy only from its hardware generator, but Coinkite traced the failure to a build and link error that left the setting meant to disable the software path without effect, sending the random-number call to MicroPython’s Yasmarang PRNG, which entered the seed path in March 2021. Affected seeds carry about 72 bits of entropy instead of the expected 128 bits after 594.5 BTC was...