Trezor Evaluates Post-Quantum Signature Trade-Offs for Bitcoin Hardware Wallets

Hardware wallet manufacturer Trezor is preparing for user-experience and security challenges tied to a future quantum-resistant $BTC network, according to an interview with Chief Technology Officer Tomáš Sušánka ¹. The discussion centers on SHRINCS, a candidate post-quantum signature scheme proposed by Blockstream Research Director Jonas Nick and cryptographer Mikhail Kudinov ¹. At the time of writing, Bitcoin traded at $71,361, down 4.2% over 24 hours.

SHRINCS employs a composite hash-based framework that gives users a choice between stateful and stateless signatures ¹. Stateful signatures are roughly ten times smaller than stateless alternatives, offering substantial fee and speed advantages, but require strict tracking of remaining signing budgets ¹. Reusing one-time keys beyond this limit leaks cryptographic data, allowing attackers to forge signatures and steal funds ¹. Conversely, stateless signatures avoid state-tracking failure modes but carry significantly larger transaction sizes, creating higher network fee burdens ¹.

Hardware Bottlenecks and Migration Realities

To shield everyday users from catastrophic state-tracking mistakes, Trezor is evaluating an interface model that defaults to larger stateless signatures while relegating stateful options to advanced settings ¹. Sušánka highlighted the operational friction of stateful keys, particularly in common multi-device setups where two hardware wallets share the same recovery seed without a shared state synchronization channel ¹. Broader migration debates have also surfaced in related network initiatives, such as Bitcoin Developers Propose BIP 360 to Mitigate Long-Exposure Quantum Vulnerabilities.

Beyond transaction-level cryptography, Sušánka noted that hardware signing devices themselves rely on traditional cryptography vulnerable to quantum attacks for internal firmware validation and device authentication ¹. Trezor has begun addressing this vulnerability at the physical layer by deploying models like the Trezor Safe 7, which incorporates post-quantum cryptographic primitives for internal authentication ¹. However, on-chain transactions generated through such hardware will only gain quantum resistance once the broader Bitcoin protocol activates a compatible post-quantum signature upgrade ¹.