Ledger CTO Warns Hardware Wallet Security Must Evolve Against AI Threats

The recent Coldcard exploit, which exposed a flaw allowing attackers to guess private keys and steal approximately $130 million in Bitcoin, has prompted Ledger CTO Charles Guillemet to sound the alarm about hardware wallet security standards.

The vulnerability stemmed from a firmware bug dating to March 2021. The device relied on a software fallback to generate recovery seed phrases instead of using its dedicated hardware random number generator, making some private keys predictable. Coldcard maker Coinkite disclosed the issue last week and released patched firmware, urging affected users to transfer funds to newly generated wallets.

Guillemet told Decrypt that the incident underscores how cryptographic randomness is fundamental to hardware wallet security. He noted that Ledger's own devices use a certified hardware random number generator built into a Secure Element with no software fallback, generating the full entropy required for seed phrases.

Beyond the immediate vulnerability, Guillemet raised broader concerns about how hardware wallet security is evaluated. He observed that the Coldcard flaw remained visible in public code for over five years before an adversary reportedly used artificial intelligence to discover it. This points to a critical shift in the threat landscape: AI now allows attackers to scan code and identify vulnerabilities at machine speed. Guillemet argued that defense must adapt accordingly, relying on security by design, hardware architecture, and mathematical foundations rather than obscurity.