SHRINCS: 324-byte stateful post-quantum signatures with static backups

The conversation highlights an innovative approach towards ensuring the security of state information in applications, particularly focusing on safeguarding this data from users themselves. The suggested method revolves around the utilization of a Trusted Platform Module (TPM) to store a decryption key, while keeping the actual state data encrypted and stored on-disk. This strategy ensures that even if the encrypted state is backed up, without the unique TPM’s key, decrypting the state would be unfeasible. Consequently, this setup allows the application layer to manage read/write locking mechanisms for these encrypted state files effectively.

An alternative proposition involves storing the seed of an XMSS key within the TPM. This method has the advantage of rendering backed-up state files harmless. In scenarios where these files are restored, they cannot be used mistakenly for signing purposes absent the necessary user input of their seed phrase. This requirement introduces an additional layer of security by necessitating explicit user action to fully restore wallet functionality. The discussion reflects on the paradoxical nature of designing systems that intentionally complicate file recovery processes. This consideration is rooted in enhancing overall security measures, suggesting a deliberate shift towards prioritizing data protection over ease of recovery.