P256 Signer

This library implements the decoding and verification of a signed Webauthn payload following the EIP 1271 providing an implementation of Standard Signature Validation Method when the account is a smart contract.

Contracts overview

FCL/FCL_elliptic.sol

The FCL_Elliptic_ZZ library implements computation of ECDSA verification using the secp256r1 curve.It uses a XYZZ system coordinates. This contract is from here. The original repository also contains tests.

Webauthn.sol

The Webauthn library implements the decoding and verification of a signed Webauthn payload.

P256Signer.sol

The P256Signer contract represents a Gnosis Safe signer for a given secp256r1 public key.

P256SignerFactory.sol

The P256SignerFactory contract is a factory for P256Signers. It allows us to have deterministic addresses for a given secp256r1 public key.

Signature malleability

Clients need to note there is a potential signature malleability by replacing (r, s) by (r, -s mod n). It is the responsibility of the client to check the message signed is played only once if necessary.

Launch tests

You will need INFURA_ID=<your_infura_id> in your env variables.
You will need forge installed, see foundry book for instructions here.

Install FCL dependency:

forge install

To launch both hardhat and forge tests:

yarn test

Hardhat

npx hardhat test

Forge

forge test

Deploy

HARDHAT_NETWORK=<target_network> npx hardhat deploy