Talk Proposal Submission
Thank you for submitting a talk for Bitcoin 2026!
Please fill out the sections below as completely as possible.
Title of Talk
Cross-Input Signature Aggregation Proposal
Speaker Name
Fabian Jahr
Talk Description
What is this talk about?
The idea of CISA (Cross-Input Signature Aggregation) has existed since Schnorr signatures were introduced to Bitcoin along with the Taproot upgrade. Work on this concept was abandoned for some time with research focus being placed on simpler soft-forks and non-softfork improvements. However, over the last three years continuous progress has been made so that CISA now has it's first fully specified proposal and a PoC implementation. The presentation will summarize the journey and the findings that let here and show what the proposal includes.
What will attendees learn?
Which research progress was made along the way to make the proposal feasible, how the proposal is specified and what trade-offs were being made, where they can find all the materials produced, what the exact benefits are from a potential deployment of this proposal as well as potential downsides, status on a collaboration with the PayJoin foundation
Why is this talk valuable?
At the 2024 conference there was a panel on CISA that stayed pretty high level which I was a part of. This talk would allow me to follow up and show the progress that has been made and show what is possible if this in deployed to Bitcoin. It should renew interest in the concept and spark discussions among those working or interested in improving Bitcoin with future soft-forks.
Technical Level
Duration
Speaker Bio
Fabian is an open source Bitcoin developer with focus on Bitcoin Core and related projects. He supported by Brink and his CISA work has also received support by HRF. His focus is innovations enabled by Schnorr signatures, dedicated in-depth code review of important Bitcoin Core initiatives, ASMap development, and more.
Relevant Links
https://github.com/fjahr/
https://cisaresearch.org/
https://www.youtube.com/watch?v=HvI7NPI_Pk0
https://www.youtube.com/watch?v=RGdeleSqpIU
https://www.youtube.com/watch?v=96n34yZAO1U&t=15199s
https://github.com/fjahr/cisa-playground
bitcoin-core/secp256k1#1754
bitcoin-core/secp256k1#1566
Preferred Day/Time (Optional)
I would really like to speak in the morning on the first day because my energy level is higher, I can enjoy the rest of the conference more and get more out of the conversations with the other participants which have seen my talk and can give me feedback on what I presented.
Talk Proposal Submission
Thank you for submitting a talk for Bitcoin 2026!
Please fill out the sections below as completely as possible.
Title of Talk
Cross-Input Signature Aggregation Proposal
Speaker Name
Fabian Jahr
Talk Description
What is this talk about?
The idea of CISA (Cross-Input Signature Aggregation) has existed since Schnorr signatures were introduced to Bitcoin along with the Taproot upgrade. Work on this concept was abandoned for some time with research focus being placed on simpler soft-forks and non-softfork improvements. However, over the last three years continuous progress has been made so that CISA now has it's first fully specified proposal and a PoC implementation. The presentation will summarize the journey and the findings that let here and show what the proposal includes.
What will attendees learn?
Which research progress was made along the way to make the proposal feasible, how the proposal is specified and what trade-offs were being made, where they can find all the materials produced, what the exact benefits are from a potential deployment of this proposal as well as potential downsides, status on a collaboration with the PayJoin foundation
Why is this talk valuable?
At the 2024 conference there was a panel on CISA that stayed pretty high level which I was a part of. This talk would allow me to follow up and show the progress that has been made and show what is possible if this in deployed to Bitcoin. It should renew interest in the concept and spark discussions among those working or interested in improving Bitcoin with future soft-forks.
Technical Level
Duration
Speaker Bio
Fabian is an open source Bitcoin developer with focus on Bitcoin Core and related projects. He supported by Brink and his CISA work has also received support by HRF. His focus is innovations enabled by Schnorr signatures, dedicated in-depth code review of important Bitcoin Core initiatives, ASMap development, and more.
Relevant Links
https://github.com/fjahr/
https://cisaresearch.org/
https://www.youtube.com/watch?v=HvI7NPI_Pk0
https://www.youtube.com/watch?v=RGdeleSqpIU
https://www.youtube.com/watch?v=96n34yZAO1U&t=15199s
https://github.com/fjahr/cisa-playground
bitcoin-core/secp256k1#1754
bitcoin-core/secp256k1#1566
Preferred Day/Time (Optional)
I would really like to speak in the morning on the first day because my energy level is higher, I can enjoy the rest of the conference more and get more out of the conversations with the other participants which have seen my talk and can give me feedback on what I presented.