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

The implemented content is:

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

FCL_elliptic.sol: an EVM optimized implementation of sec256r1(P256), using language hacks and specificities. FLC_Webauthn.sol: implementation of the WebAuthn2/FIDO2 authentication over ECDSA with P256

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

FCL_cairo_secp : optimization of the ECDSA function over sec256r1, using starkware implementation with ec_mulmuladdW_sec256k1 (original implementation from Starkware commons here:https://github.com/https://github.com/starkware-libs/cairo-lang/tree/master/src/starkware/cairo/common/cairo_secp)

FCL_cairo_secp256k1 : optimization of the ECDSA function over sec256k1 using ec_mulmuladdW_sec256r1 (original implementation from Cartridge here:https://github.com/cartridge-gg/cairo-secp256r1).

FCL_musig2: Original implementation of the Schnorr verification algorithm. Please note that it is a custom implementation (cryptographically equivalent, but not identical to BlockStream implementation). Namely arbitrary domain separator, choice of hash, byte ordering and annoying little choices are not compatible with Musig2 BIP proposal.

FCL_ecdsa_precompute.sage : precompute bytecode contract to speed up ecdsa verification for a given key.

PoC of integration of FCL sources given as examples and benchmark.

External repos.

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