Trezor is preparing to address the unique security and user experience challenges that could emerge with a post-quantum Bitcoin, as highlighted by CTO Tomáš Sušánka. As the Bitcoin community considers SHRINCS—a leading candidate for quantum-resistant signatures—wallet manufacturers face critical decisions around how to implement these changing cryptographic standards.
SHRINCS: The Path Toward Quantum-Resistant Bitcoin
SHRINCS, proposed by Blockstream Research Director Jonas Nick and cryptographer Mikhail Kudinov, introduces a composite hash-based signature system. It allows users to choose between large, reusable “stateless” signatures and smaller, highly efficient “stateful” signatures. The latter are appealing for efficiency but bring significant security risks if reused beyond their prescribed signature budget.
With stateful signatures, users must monitor a strict signing limit. Accidental overuse of these keys can leak cryptographic details that enable malicious actors to forge signatures and potentially steal funds. As Sušánka emphasized, this adds a complex layer of responsibility for both users and developers. “You’re giving them an option to mess up,” he said in an interview on MARA Foundation TV, referencing the risks inherent in state tracking.
Sušánka explained that safeguarding users should be the developer’s responsibility, not something left solely to users navigating technical pitfalls.
If SHRINCS is adopted for Bitcoin, wallet providers will need to implement rigorous state management to protect users from security edge cases. Sušánka noted the burden this creates, especially when users operate multiple devices with the same recovery seed but cannot synchronize the signature state between them.
Trezor’s Security Approach and User Experience
To limit security risks, Trezor is considering making stateless signatures—while heavier and slower—the default option, with stateful signatures accessible only through advanced settings. This approach aims to shield ordinary users from unnecessary risk, balancing safety against efficiency.
Sušánka observed that “stateful signatures are 10 times smaller” than their stateless counterparts, but the trade-off involves a significant security burden.
While SHRINCS leverages cryptography similar to Bitcoin’s SHA-256, Sušánka acknowledged the difficulty of relying on users to handle state management. He underscored that critical trade-offs must be weighed carefully, as developers strive to maintain both usability and robust security.
Ongoing work on solutions reflects the complexity of post-quantum upgrades for Bitcoin custody. Trezor recently introduced the Safe 7 hardware wallet, which supports post-quantum cryptography for device authentication. However, Sušánka cautioned that transactions from such devices will only be “quantum-secure” after Bitcoin itself embraces post-quantum security.
Preparing for a Post-Quantum Bitcoin Future
Sušánka also highlighted that most current hardware wallets rely on cryptographic standards vulnerable to quantum threats, especially for firmware and device authentication. He argued that genuine quantum protection will require device manufacturers to transition to post-quantum cryptography across all layers, not solely for wallets but also for their supporting infrastructure.
Users seeking post-quantum resilience need to consider not only the cryptographic signatures used for transactions but also whether their device firmware and authentication systems meet emerging security standards.
During the MARA Foundation TV conversation, Sušánka urged the developer community to act proactively, warning that facilitating the migration of millions of users to post-quantum security will be time-consuming. He remarked, “People should be ready to make compromises,” cautioning against an overly rigid approach to such fundamental changes.
As the Bitcoin ecosystem prepares for post-quantum upgrades, monitoring the progress of signature schemes like SHRINCS and their impact on user experience remains essential. For investors and developers tracking these rapid developments, CryptoAppsy’s real-time news monitoring and coin-specific alerts offer a practical way to stay informed about protocol changes and hardware wallet updates as soon as they are announced.
