Fresh Crypto Lib (FCL)

The Fresh Crypto Lib is a set of functions for blockchain systems such as Wallet, SmartContracts.

Content

The implemented content is:

• sec256r1 optimizations for EVM chains and Starknet
• an ecdaa implementation using blockchain primitives
• a Starknet dedicated musig2 implementation

Directory solidity:

• FCL_elliptic.sol: an EVM optimized implementation of sec256r1(P256), using language hacks and specificities, as described in paper https://eprint.iacr.org/2023/939.pdf.
• FCL_eddsa.sol : an EVM optimized implementation of ed25519, using same paper tricks.
• FCL_sha512.sol : implementation of the SHA512 primitive (WIP, not working)
• FLC_Webauthn.sol: implementation of the WebAuthn2/FIDO2 authentication over ECDSA with P256

Directory cairo0.9:

• FCL_ec_mulmuladd.cairo: an implementation of the operation aP+bQ (addition of the results of two distincts point multiplication by scalar a and b). It uses the Shamir's trick with the windowing method. signature_opt.cairo : optimisation of ECDSA verification using ec_mulmuladd_W function

Directory sage:

• FCL_ecdsa_precompute.sage : precompute bytecode contract to speed up ecdsa verification for a given key.
• FCL_ecdaa : sage reference for a blockchain implementation of ECDAA
• FCL_pairings : sage implementation of curve and pairing computation over BN254 (aka altbn128) and BLS12381 using INRIA sources.

Acknowledments:

Building Blocks

The following repos are used as building blocks in the FCL:

• Aurore Guillevic's Gitlab at INRIA: https://gitlab.inria.fr/tnfs-alpha/alpha/-/tree/190b87732901750ed1438a8cf340571531d32230/sage/tnfs for its generic sagemath BN and BLS curves and pairing implementation.
• Paul Miller Noble javascript library for its G1 implementation of BN254 and BLS12, and keccak256. https://paulmillr.com/noble/

Benchmark

The following repos have been used in benchmarks:

• Alembic/cometh:https://github.com/alembic-tech/P256-verify-signature/blob/main/contracts/EllipticCurve.sol
• MaxRobot : https://github.com/maxrobot/elliptic-solidity
• Numerology : https://github.com/nucypher/numerology
• Obvious : https://github.com/itsobvioustech/aa-passkeys-wallet

FCL in the wild

• Academic paper: https://eprint.iacr.org/2023/939 for EthCC2023
• Braavos https://github.com/myBraavos/efficient-secp256r1/blob/develop/src/secp256r1/ec_mulmuladd.cairo
• Cartridge cartridge-gg/cairo-secp256r1#3
• EIP665 PR#7515 :ethereum/EIPs#7515
• Presentation made at EthCC 2023 in Paris: https://www.youtube.com/live/Rlq21oA_FA8

License

License: This software is licensed under MIT License (see LICENSE FILE at root directory of project).