2-of-2 MPC Signer – DLKs23

This repo showcases a 2-of-2 MPC signer.

Prepares, signs, and broadcasts Ethereum transactions using threshold signatures (MPC).

1. Architecture

1.1 Component scope

The Orchestrator holds no shares; each cosigner holds exactly one.

External actors (calls to the public API, and the Sepolia RPC node) are not components.

1.2 DKG workflow

A one-time ceremony. The Orchestrator triggers DKG on both cosigners. Then the cosigners run the DKLs23 DKG rounds directly P2P and each persists its own share.

The derived address is reported back and independently verified by the operator.

1.3 Signing and broadcast workflow

The runtime path. The client calls the Orchestrator (sovra-api) to prepare and sign. Then the Orchestrator triggers signing on both cosigners.

The cosigners run the DKLs23 rounds directly P2P and return the final signature.

The Orchestrator assembles and verifies the signature, then broadcasts to Sepolia.

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2. Public HTTP API

Three transaction-lifecycle endpoints (prepare, sign, broadcast), plus operator endpoints for DKG.

POST /v1/prepare

Build an unsigned EIP-1559 transaction from intent.

POST /v1/sign

Execute signing across both cosigners over the supplied unsigned transaction.

POST /v1/broadcast

Submit the signed transaction to Sepolia and wait up to 30 seconds for a receipt.

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Goal of this repository:

• DKG (Distributed Key Generation) sets up 2 shards - DKLs23 DKG
• Take a tx hash to sign a Sepolia transaction - DKLs23 rounds
• Broadcast it – using a public RPC
• Be verifiable on Etherscan
• Two shards on different machines: one in a raspberry pi & one hosted on cloud (for demo purposes)

Out of scope, for now

These are deliberate deferrals, not gaps:

• API authentication, authorization, rate limiting
• Share encryption at rest (filesystem permissions only for PoC)
• TLS certificate lifecycle (rotation, revocation)
• Concurrent signing sessions (global lock for PoC)
• Observability backend (local JSON logs only)
• Multi-chain support (Sepolia only)
• Automated backup and restore (manual archive only)
• Recovery beyond 2-of-2 threshold

/!\ This repo is for demo purposes only.

It uses the silence-laboratories DKLs23 as MPC TSS crypto implementation that has been audited but that is under commercial license.