39 stable releases (4 major)
4.4.0 | May 5, 2022 |
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4.3.3 | Jan 23, 2022 |
4.3.2 | Dec 21, 2021 |
4.3.0 | Nov 22, 2021 |
0.2.3 | Mar 26, 2020 |
#2987 in Magic Beans
22 downloads per month
Used in 4 crates
(3 directly)
220KB
6K
SLoC
Fawkes-Crypto - zkSNARKs framework
Abstract
Fawkes-Crypto is a lightweight framework for building circuits in bellman, using groth16 proving system and BN254 curve.
The framework is targeted to use best practices for circuit building from circom and sapling-crypto.
Final fields and circuit math are wrapped and operators are implemented, so, in most cases if you want to type a+b
, you can do it.
Example
Here is an example, how Merkle tree implementation is working. Also you may check the rollup here.
#[derive(Clone, Signal)]
#[Value="MerkleProof<CS::F, L>"]
pub struct CMerkleProof<'a, CS: ConstraintSystem, const L: usize> {
pub sibling: SizedVec<CNum<'a, CS>, L>,
pub path: SizedVec<CBool<'a, CS>, L>
}
pub fn c_poseidon_merkle_proof_root<'a, CS: ConstraintSystem, const L: usize>(
leaf: &CNum<'a, CS>,
proof: &CMerkleProof<'a, CS, L>,
params: &PoseidonParams<CS::F>
) -> CNum<'a, CS> {
let mut root = leaf.clone();
for (p, s) in proof.path.iter().zip(proof.sibling.iter()) {
let first = s.switch(p, &root);
let second = &root + s - &first;
root = c_poseidon( [first, second].as_ref(), params);
}
root
}
Signal
is a sparse linear combination of inputs, based on ordered linked list, so we perform arithmetics with Signal
with U(N)
complexity. With Signal
bellman will allocate additional inputs only when you really need it (for example, in the case when you multiply two nonconstant Signal
). If you perform multiplication with constant or zero Signal
, no additional inputs will be allocated.
Benchmarks
Circuit | Constraints | Per bit |
---|---|---|
poseidon hash (4, 8, 54) | 255 | 0.33 |
jubjub oncurve+subgroup check | 19 | |
ecmul_const 254 bits | 513 | 2.02 |
ecmul 254 bits | 2296 | 9.04 |
poseidon merkle proof 32 | 7328 | |
poseidon eddsa | 3860 | |
rollup 1024 txs, 2^32 set | 35695616 |
At i9-9900K rollup is proved for 628 seconds.
Source code of the rollup is available at https://github.com/snjax/fawkes-rollup.
Circuit improvements
- We are using indeterministic subgroup checks, performing most part of computations as witness-only and perform cofactor multiplication at the circuit.
- ecmul and ecmul_cost operations are working assuming that the base point is in the subgroup. This allows us to use Montgomery (0, 0) point as adder initial state. Then the adder never reaches zero point and subgroup point, because (0, 0) is not in subgroup and we can use cheap montgomery_add circuit safely.
- improved compconstant circuit. The same PR into circomlib available here
See more as ethresear.ch here.
Authors
Igor Gulamov
Disclaimer
Fawkes-Crypto has not been audited and is provided as is, use at your own risk.
License
Fawkes-Crypto is available under Apache License 2.0 license or MIT as your choice.
Dependencies
~13MB
~385K SLoC