1 December 2025 - Pedro Moreno-Sánchez

Speaker: 

Pedro Moreno-Sánchez

Title: 

Adaptor Signatures and their Applications

Abstract: 

To enable a modular design and enhance reusability across different
cryptocurrencies, many blockchain protocols are built upon adaptor
signatures (AS). Adaptor signatures are a well-studied cryptographic
building block natively supported by most digital signature schemes used
for authorizing cryptocurrency transactions. In the context of
cryptocurrencies, AS enables users to cryptographically enforce a
trustless exchange between a financial transaction and a cryptographic
secret. Specifically, two users can lock coins into a shared account
that requires authorization from both parties to spend. Using AS, they
can create presignatures for transactions spending these coins, with
respect to a cryptographic secret w. These presignatures serve a dual
purpose: (1) Anyone who learns the secret w is guaranteed they can
locally adapt the presignature into a valid signature. (2) Anyone who
learns the adapted signature can locally extract w from the pair of
presignature and signature.

This talk provides an overview of existing research on adaptor
signatures. It presents an inherent limitation of AS-based blockchain
protocols, such as the known impossibility of realizing AS for unique
signature schemes, such as BLS signatures. Finally, this talk covers our
ongoing research on AS, including how to overcome this impossibility
result.