Unstoppable Wallets: Chain-assisted Threshold ECDSA and its Applications
- Implementation: Github
Setting
- In the threshold setting for \(t
Problem
- Solves [BROKEN LINK: 028e9e89-c0cd-461f-af52-55236b8cd2b9]
Notes
- This work assumes the existence of confidential smart contracts, i.e., blockchains that can keep a secret.
- As a result, they treat blockchain as a semi-honest non-colluding party \(P_c\).
- Since writes on a blockchain are expensive, they optimize for this in their threshold ECDSA construction. They reduce it to one write per party.
- Idea: For helper party, we can use any honest-majority protocol to implement dishonest majority protocol by assigning \(n\) shares to the parties and an additional \(t\) shares to the helper party. If \(t=n-1\), then helper and 1 honest party can work together to reconstruct.
- Idea: To generate a random share: \(P_{1}\) and \(P_{c}\) together generate shares.
- \(P_{1}\) sends \((n,t+1)\) shares of a random number to all nodes and additional \(t\) shares to \(P_{c}\)
- \(P_{c}\) sends \((n,t+1)\) shares of a random number to all nodes.
- All nodes compute their random share as the sum of these two shares.
- Repeat with \(t+1\) nodes if we want guaranteed output.
References
Guy Zyskind, Avishay Yanai, and Alex "Sandy" Pentland. 2023. “Unstoppable Wallets: Chain-assisted Threshold ECDSA and its Applications.” https://eprint.iacr.org/2023/832.