Coinkite the firm behind Coldcard just rolled out firmware that skips fresh wallet seeds until owners add their own randomness by hand.
Boot Check Aims at the Flaw 🦇
That requires at least 50 dice rolls 128 coin flips or 65 timed key presses three weeks after a random number generator flaw risked customer funds to attackers. Coldcard devices run distinct firmware paths so the update brings numbers 5.6.1 for the Mk4 and Mk5 plus 1.5.1Q for the larger Q model with its keyboard and QR scan. Coinkite stated the user input layers atop device randomness from the STM32 TRNG and both secure elements. Coldcard once pulled seed entropy solely from hardware but a build error disabled the software path setting and funneled calls to MicroPython’s Yasmarang PRNG since March 2021. Affected seeds hold roughly 72 bits of entropy instead of 128 after 594.5 BTC vanished from 500 addresses on July 30. Firmware 5.6.1 now checks at boot that random calls hit the hardware path and halts if not. Coinkite swapped Yasmarang for a SHA-256 Hash_DRBG seeded at startup with a full 256-bit digest from secure elements. Key mashing follows Peter Todd’s design hashing timing at CPU resolution.
Prior Seeds Demand Migration 💀
Installing the update leaves existing vulnerable seeds exposed so anyone with seeds from affected firmware between 2021 and July 2026 must create new ones and shift their Bitcoin. Mk2 and Mk3 stay on minimum version 4.2.0. A compromised USB host could alter transactions after approval but the device now rechecks bytes before signing and warns on changes. Coinkite added a Security Status page with four reviews including hardware RNG tests. The checks skip a full audit of every binary as confirmed losses exceed 100 million with 1596 BTC taken from about 7300 addresses and another wave grabbing nearly 449 BTC on August 3. 🖤 🌑 🕸️ 🔮 🐈⬛ 🩸 🦇
Just another echo from the void by iconofsin.eth 💖
