Canton MPC PoC

MPC-based ERC-20 custody on Canton. Daml smart contracts manage vault state (deposits, withdrawals, holdings) while a TypeScript MPC service signs EVM transactions using threshold-derived keys via signet.js.

Prerequisites

Tool	Version	Install
Java	21+	Temurin
Daml SDK (DPM)	3.4.11	curl -sSL https://get.digitalasset.com/install/install.sh | sh
Node.js	24+	nodejs.org
pnpm	10+	corepack enable && corepack prepare pnpm@latest --activate

After installing DPM, make sure ~/.dpm/bin is on your PATH.

Configuration

The MPC service reads CANTON_JSON_API_URL from test/.env and passes it to the CantonClient constructor. Defaults to http://localhost:7575 if unset. Tests always use the default.

# In test/.env — point to a remote or non-default sandbox
CANTON_JSON_API_URL=http://my-canton-node:7575

See test/.env.example for all available variables.

Quick Start

1. Build the DAR and generate codegen

dpm build --all
cd test
pnpm run codegen:daml
pnpm install

2. Start the Canton sandbox

In a separate terminal (keep it running):

cd test
pnpm daml:sandbox

Wait until you see the JSON API listening on port 7575. You can verify with:

curl -sf http://localhost:7575/docs/openapi > /dev/null && echo "Ready"

3. Run tests

cd test
pnpm test          # single run (unit + integration)

One-liner rebuild

If you change Daml sources and need a full clean rebuild (requires sandbox running for OpenAPI codegen):

cd test && pnpm generate

This runs clean -> daml:build -> codegen:daml -> codegen:api -> install.

Daml Unit Tests

These don't need the sandbox:

dpm build --all
for pkg in daml-abi daml-uint256 daml-evm-types daml-eip712 daml-vault; do
  (cd daml-packages/$pkg && dpm test)
done

dpm test does not support --all — each package must be tested individually.

Sepolia E2E Tests

End-to-end tests that exercise the full deposit/withdrawal lifecycle against a live Sepolia RPC and the Canton sandbox.

Setup

cd test
cp .env.example .env

Fill in the required values:

Variable	Description
CANTON_JSON_API_URL	(optional) Canton JSON API base URL (default http://localhost:7575)
SEPOLIA_RPC_URL	Sepolia JSON-RPC endpoint (Infura, Alchemy, etc.)
MPC_ROOT_PRIVATE_KEY	0x-prefixed secp256k1 private key (64 hex chars)
MPC_ROOT_PUBLIC_KEY	Uncompressed SEC1 public key (04 + x + y, no 0x prefix)
VAULT_ID	Vault discriminator for MPC key derivation
FAUCET_PRIVATE_KEY	(optional) Defaults to MPC_ROOT_PRIVATE_KEY
ERC20_ADDRESS	(optional) Defaults to test USDC on Sepolia

Fund the faucet

pnpm sepolia:preflight    # prints faucet address + current balances

Send to the faucet address:

• ~0.002 ETH for gas per test run
• ERC-20 tokens for the deposit amount

Run

# Start sandbox in a separate terminal first, then:
pnpm test          # runs all tests including Sepolia e2e when env is set

Design

• Deposit flow — end-to-end deposit lifecycle: auth cards, MPC signing, Sepolia submission, and Canton claim
• Withdrawal flow — end-to-end withdrawal lifecycle: holding burn, MPC signing, Sepolia submission, and refund-on-failure

Available Scripts

From test/:

Script	Description
pnpm test	Run all tests (unit + integration, Sepolia e2e if env is set)
pnpm daml:build	Build the DAR
pnpm daml:test	Run Daml Script tests
pnpm daml:sandbox	Start Canton sandbox with JSON API on :7575
pnpm codegen:daml	Regenerate Daml JS codegen from built DAR
pnpm codegen:api	Regenerate OpenAPI types (requires running sandbox)
pnpm generate	Full clean rebuild: DAR + codegen + install
pnpm sepolia:preflight	Check faucet balances and print deposit addresses

From root:

Script	Description
pnpm check	Typecheck + lint + knip + format check
pnpm fix	Auto-fix lint + format