Decentralized Threshold Signature Service Implementation

• Team Name: Rui Morais
• Payment Address:
  • FIAT (Sent by email to grants@web3.foundation on 09/08/2024, 16:07 UTC+1)
  • Polkadot: 14bBGQFAgKqdbGVDSWkm6dA8ZQzt9GxGSTALrD8SeafWW9gL
• Level: 2

Project Description 📄

General Overview

This project is a continuation of this one and aims to build a decentralized threshold signing service leveraging the Olaf protocol. The service will operate off-chain, providing a secure and cost-effective alternative to on-chain threshold signature mechanisms within the Substrate/Kusama/Polkadot ecosystem.

Technical Details

Each participant in the threshold signing group will run a browser-based application that performs decentralized key generation and signing operations through the Olaf threshold signature protocol, compiled to WebAssembly (WASM). The networking layer is built using JavaScript and libp2p for peer discovery and communication.

🌐 Networking Layer (JavaScript)

Transport

• Peers connect to a relay server using WebSockets.

Discovery

• When a peer connects, it sends its Substrate/Polkadot/Kusama address to the relay server.

• The relay server assigns the peer a random libp2p Peer ID and stores the mapping:
  Address → Peer ID

• Peers can query the relay server with a known blockchain address to obtain the corresponding Peer ID.

Direct Peer Communication

• Once a Peer ID is obtained, the peer establishes a WebRTC connection using libp2p.
• All protocol messages are exchanged via this secure, direct P2P channel.

🔐 Cryptographic Protocol (Rust → WASM)

The cryptographic logic is written in Rust and compiled to WebAssembly (WASM) for browser use.

Core Functionality

• Distributed Key Generation (DKG) to derive a shared threshold public key.
• Threshold Signing for signing Substrate/Kusama/Polkadot extrinsics.

State Management

• Key shares and protocol state are stored in browser-local storage (e.g., IndexedDB).

Ecosystem Fit

This project is useful for any Substrate/Kusama/Polkadot based project that wants to use a secure off-chain decentralized threshold signature service that is cheaper than using the theshold signing funcionality of the network directly.

Related Projects

The most similar project we found is this, but it is out of date and unmantained.

Team members

• Rui Morais

Contact

• Contact Name: Rui Morais
• Contact Email: ruipedromorais11@gmail.com
• Github: https://github.com/fiono11
• Linkedin: https://www.linkedin.com/rui-morais

Team's experience

• Obtained a PhD in Computer Science with the thesis "Contributions to Permissionless Decentralized Networks for Digital Currencies Based on Delegated Proof of Stake" (awaiting for the defense).
• Published the following papers:
  • Echidna: A New Consensus Algorithm for Efficient State Machine Replication (IEEE BCCA 2023)
  • Nero: A Deterministic Leaderless Consensus Algorithm for DAG-Based Cryptocurrencies (Algorithms 2022)
  • A tool for implementing privacy in Nano (IEEE DAPPS 2020)
  • Adamastor: a New Low Latency and Scalable Decentralized Anonymous Payment System (Arxiv)
• Has graduated the PBA Hong Kong cohort.

Development Roadmap 🔩

Overview

• Total Estimated Duration: 3 months
• Full-Time Equivalent (FTE): 1 FTE
• Total Costs: 30,000 USD
• DOT %: 50%

Milestone 1 - Peer Discovery via Blockchain Address

• Estimated duration: 1 month
• FTE: 1
• Costs: 10,000 USD

Number	Deliverable	Specification
0a.	License	GPLv3
0b.	Documentation	We will provide inline documentation of the code.
0c.	Testing and Testing Guide	Core functions will be fully covered by comprehensive unit tests to ensure functionality and robustness. In the guide, we will describe how to run these tests.
0d.	Docker	We will provide a Dockerfile(s) that can be used to test all the functionality delivered with this milestone.
1.a	Peer Discovery via Blockchain Address	Two browsers connect to a relay server, register with a Substrate/Kusama/Polkadot address, discover each other, and exchange messages directly over WebRTC using libp2p.

Milestone 2 - Distributed Key Generation

• Estimated duration: 1 month
• FTE: 1
• Costs: 10,000 USD

Number	Deliverable	Specification
0a.	License	GPLv3
0b.	Documentation	We will provide inline documentation of the code.
0c.	Testing and Testing Guide	Core functions will be fully covered by comprehensive unit tests to ensure functionality and robustness. In the guide, we will describe how to run these tests.
0d.	Docker	We will provide a Dockerfile(s) that can be used to test all the functionality delivered with this milestone.
1.a	Distributed Key Generation	Two browsers exchange messages and successfully produce a shared threshold public key using the Olaf DKG protocol compiled to WASM.

Milestone 3 - Threshold Signature

• Estimated duration: 1 month
• FTE: 1
• Costs: 10,000 USD

Number	Deliverable	Specification
0a.	License	GPLv3
0b.	Documentation	We will provide both inline documentation of the code and a basic tutorial that explains how the service can be used.
0c.	Testing and Testing Guide	Core functions will be fully covered by comprehensive unit tests to ensure functionality and robustness. In the guide, we will describe how to run these tests.
0d.	Docker	We will provide a Dockerfile(s) that can be used to test all the functionality delivered with this milestone.
0e.	Article	We will publish an article/workshop that explains how the service works under the hood and how it can be used from a user perspective.
1.a	Threshold Signature	Two browsers exchange messages and produce a valid threshold signature over a given Substrate/Kusama/Polkadot extrinsic using the Olaf protocol compiled to WASM.

Future Plans

Build a production-ready, secure Progressive Web App (PWA) that includes:

• Robust asynchronous peer-to-peer communication.
• Support for configurable t-out-of-n threshold schemes.
• Add proof of ownership to prevent address spoofing.
• Implement a network of relay servers to achieve full decentralization.