delvingbitcoin

## Lamport signatures and other CAT tricks

### Posted on: December 3, 2023 14:55 UTC

In the context of cryptocurrency transactions, a particular concern is addressed regarding the safety and verification mechanisms for keyspend operations.

The sender of the message discusses a method to ensure the legitimacy of such operations by revealing a preimage 't' of a tweak, which clients could then verify through cryptographic calculations. Specifically, they suggest that clients could check if 'Q', presumably a public key or some other point on an elliptic curve, equals the sum of the generator point 'G' and the product of 'G' and 't'. This process would act as a safeguard against unauthorized transactions.

However, the sender acknowledges a potential flaw in this approach. An adversary might circumvent the check by calculating a different point '(a+b)G' that equals '(t+1)G', where 'a' and 'b' are variables in the elliptic curve equation, thus posing a question about the robustness of this verification method.

The sender also raises a question about the possibility of enforcing script-only transactions while maintaining compatibility with the current address format. This suggests a desire to strengthen security measures without having to alter the existing infrastructure significantly. The underlying challenge is finding a balance between enhancing security protocols for keyspend activities and ensuring smooth functionality within the established system.