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2PC-MPC

Overview​

2PC-MPC, as described in the "2PC-MPC: Emulating Two Party ECDSA in Large-Scale MPC" paper (2PC-MPC V1) and the "Practical Zero-Trust Threshold Signatures in Large-Scale Dynamic Asynchronous Networks" paper (2PC-MPC V2) by the dWallet Labs research team, is a novel MPC protocol designed specifically for dWallets, and Ika.

Advantage​

These are some of the key features setting 2PC-MPC apart from the preceding TSS protocols used in Web3:

  • Non-collusive: both a user and a threshold of the network are required to participate in signing.
  • Scalable & Massively Decentralized: can support hundreds or thousands of nodes on the network side.
  • Locality: communication and computation complexities of the user remain independent of the size of the network (This is not fully implemented yet due to a restriction in Bulletproofs, and coming soon).
  • Identifiable Abort: malicious behavior of one of the nodes aborts the protocol identifiably, which is an important requirement in a permissionless and trustless setting.

Structure and Performance​

The 2PC-MPC protocol can be thought of as a "nested" MPC, where a user and a network are always required to generate a signature (2PC — 2 party computation), and the network participation is managed by an MPC process between the nodes, requiring a threshold on par with the consensus threshold. This structure creates non-collusivity, as the user is always required to generate a signature, but also allows the network to be completely autonomous and flexible, as it is transparent to the users of the network.

2PC-MPC exhibits superior performance as well, with its linear-scaling in communication - O(n) - and due to novel aggregation & amortization techniques, an amortized cost per-party that remains constant up to thousands of parties — practically O(1) in computation for the network, whilst being asymptotically O(1) for the user: meaning the size of the network doesn't have any impact on the user as its computation and communication is constant.

With the release of 2PC-MPC V2, the protocol has been significantly enhanced to address real-world blockchain conditions. It now supports not only threshold ECDSA but also Schnorr and EdDSA signatures, and operates efficiently in asynchronous broadcast networks. V2 introduces dynamic participant quorums so that signers can change between rounds, aligning with permissionless validator sets. Client interaction has been streamlined: presign generation is now non-interactive and fully O(1) for the user, reducing overhead and enabling reuse across signers. Security has been strengthened with improved unforgeability assumptions and proactive abort handling, while efficiency has been boosted with reduced round complexity for DKG and presign. Additional upgrades include reconfiguration support for participants joining or leaving without resharing, weighted threshold structures optimized for PoS systems, and compatibility with HD wallets (BIP32) and secure wallet transfer. Collectively, these advances make 2PC-MPC V2 more scalable, flexible, and secure—positioning it as a practical backbone for Ika and dWallets.

The goal of Ika is to support millions of users, and tens of thousands of signatures per second, with thousands of validators. 2PC-MPC, and its future improvements and optimizations planned, are how that ambitious goal will be achieved.

Implementation​

The 2PC-MPC protocol's pure-rust implementation can be found here.