7 votes
Accepted

What block space savings would we get for coinjoins (and payjoins) if we had cross input signature aggregation?

Cross-input signature aggregation (CISA) refers to an idea to produce one shared signature that covers multiple inputs in one transaction. The aggregation is made possible by the linearity of the ...
  • 65.2k
6 votes
Accepted

Will cross-input signature aggregation need a new output type?

Cross-Input Signature Aggregation (CISA) is an idea for allowing multiple inputs to be covered by a single signature. One of the main motivations is that it would allow multiple users to combine ...
  • 65.2k
4 votes
Accepted

What makes cross input signature aggregation complicated to implement?

Pieter Wuille answered this on Twitter. The most important complication of cross input aggregation is explained in this Bitcoin dev mailing list post by AJ Towns. TL;DR: if softforks change which ...
3 votes

What is cross-input signature aggregation and how would it work?

The idea behind CISA is to only provide a single signature per Bitcoin transaction even when there are multiple inputs. A key advantage of the Schnorr signature algorithm over ECDSA is its linearity. ...
  • 65.2k
3 votes
Accepted

What is the difference between key aggregation and signature aggregation?

As Pieter Wuille states here key aggregation is completed at address creation time not at signing time or post signing time. Of course, key aggregation has an impact on the signing algorithm, and ...
2 votes

What block space savings would we get for coinjoins (and payjoins) if we had cross input signature aggregation?

Murch answered this on Twitter. The signatures for P2TR are part of the witness data already, and Schnorr sigs are only 64 bytes. Each aggregated signature but the last would need a one byte ...
1 vote

What is cross-input signature aggregation and how would it work?

Schnorr Signatures and public keys can be aggregated (added together) such that S1 + S2 = S3 and P1 + P2 = P3 where (S3, P3) is a valid signature-pubkey pair IFF (S1, P1) and (S2,P2) were valid ...

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