Hi Ava, Is it safe to allow multiple participants to have the same public key? If deterministic nonce generation is used (deriving each participant's nonce from the message, the set of public keys, and the participant's private key), duplicate public keys would lead to identical nonces.
While this may not be catastrophic (since they are signing the same message and the private key likely can't be extracted) it still seems risky. Identical nonces can have unexpected consequences, and I'm not sure if all security assumptions would still hold. Curious what you think. Best, Boris On Tue, Jun 3, 2025 at 6:08 PM 'Ava Chow' via Bitcoin Development Mailing List <[email protected]> wrote: > > Hi All, > > In implementing musig() descriptor expressions, I realized that the > restriction "Repeated participant public keys are not allowed" is a bit > complicated to implement. While I don't see why anyone would want to > duplicate keys, MuSig2 does allow duplicate participant keys and > allowing them would make the implementation of musig() expressions much > easier. Thus I'd like to propose changing the BIP to remove this > restriction. > > Has anyone implemented musig() expressions yet with this restriction, > and would removing it be a significant breaking change to anyone? If > not, I'll make the change to the BIP in a few days. > > Thanks, > > Ava > > > -- > You received this message because you are subscribed to the Google Groups > "Bitcoin Development Mailing List" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/d/msgid/bitcoindev/08dbeffd-64ec-4ade-b297-6d2cbeb5401c%40achow101.com. -- Best regards, Boris Nagaev -- You received this message because you are subscribed to the Google Groups "Bitcoin Development Mailing List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/bitcoindev/CAFC_Vt5z%2BB%2BF%3DQOytZ96ptRFweX1aGBV-CXHqwv54UAyo_iiAw%40mail.gmail.com.
