777: Coldcard Is Compromised with James O'Beirne

— Coldcard RNG vulnerability: Devices produced after 2021 (MK2, MK3, MK4, Q models) contain an insufficient random number generator that limits entropy to ~70 bits instead of the required 256 bits, making private keys vulnerable to brute-force attacks.

— Migration urgency by device and setup: Single-signature users without dice rolls or strong passphrases on post-2021 devices must move funds immediately; multisig scenarios are more complex and depend on whether public keys have been revealed on-chain.

— Safe mitigations: Users who performed 99+ dice rolls during key generation or use a sufficiently complex passphrase (substantially longer than six BIP39 words) are protected and do not need to migrate.

— AI acceleration of vulnerability discovery: Language models like Claude 3 independently reproduced and identified the vulnerability within hours, demonstrating how advanced AI tools lower the barrier to finding security flaws in open-source projects.

— Multisig complexity: In multisig setups, vulnerability depends on whether all signing keys are from Coinkey products and whether their public keys have been exposed on-chain; if any non-Coinkey device is required to spend, the setup remains secure.

— Broader hardware wallet trust collapse: This event underscores systemic risks in single-vendor solutions and reinforces the need for multi-manufacturer, multi-signature custody with user-supplied entropy sources.

— Immediate action for affected users: If you own a Coldcard MK2, MK3, MK4, or Q produced after 2021 and did not use 99+ dice rolls or a cryptographically strong passphrase, migrate your funds to a trusted exchange or new secure setup within days. Perform test transactions with small amounts first to avoid panic-driven errors.

— Evaluate your current hardware setup: Multi-vendor multisig is now the practical standard for self-custody. Audit whether any single hardware manufacturer can move your coins unilaterally; if so, restructure. Bitcoin's bearer-asset nature and honeypot effect will continue surfacing vulnerabilities—assume security is an ongoing process, not a solved problem.

— Use external entropy: Going forward, incorporate physically verifiable entropy (dice rolls, hardware RNG you can audit) into key generation rather than trusting device-generated entropy alone. Plan for covenants and vault mechanisms to provide recovery windows if future hardware exploits occur.