revm_precompile/bls12_381/
g1_msm.rs

1//! BLS12-381 G1 msm precompile. More details in [`g1_msm`]
2use crate::{
3    bls12_381::{
4        utils::{pad_g1_point, remove_g1_padding},
5        G1Point,
6    },
7    bls12_381_const::{
8        DISCOUNT_TABLE_G1_MSM, G1_MSM_ADDRESS, G1_MSM_BASE_GAS_FEE, G1_MSM_INPUT_LENGTH,
9        PADDED_G1_LENGTH, SCALAR_LENGTH,
10    },
11    bls12_381_utils::msm_required_gas,
12    crypto, eth_precompile_fn, EthPrecompileOutput, EthPrecompileResult, Precompile,
13    PrecompileHalt, PrecompileId,
14};
15
16eth_precompile_fn!(g1_msm_precompile, g1_msm);
17
18/// [EIP-2537](https://eips.ethereum.org/EIPS/eip-2537#specification) BLS12_G1MSM precompile.
19pub const PRECOMPILE: Precompile =
20    Precompile::new(PrecompileId::Bls12G1Msm, G1_MSM_ADDRESS, g1_msm_precompile);
21
22/// Implements EIP-2537 G1MSM precompile.
23/// G1 multi-scalar-multiplication call expects `160*k` bytes as an input that is interpreted
24/// as byte concatenation of `k` slices each of them being a byte concatenation
25/// of encoding of G1 point (`128` bytes) and encoding of a scalar value (`32`
26/// bytes).
27/// Output is an encoding of multi-scalar-multiplication operation result - single G1
28/// point (`128` bytes).
29/// See also: <https://eips.ethereum.org/EIPS/eip-2537#abi-for-g1-multiexponentiation>
30pub fn g1_msm(input: &[u8], gas_limit: u64) -> EthPrecompileResult {
31    let input_len = input.len();
32    if input_len == 0 || !input_len.is_multiple_of(G1_MSM_INPUT_LENGTH) {
33        return Err(PrecompileHalt::Bls12381G1MsmInputLength);
34    }
35
36    let input_chunks = input.chunks_exact(G1_MSM_INPUT_LENGTH);
37    let k = input_chunks.len();
38    let required_gas = msm_required_gas(k, &DISCOUNT_TABLE_G1_MSM, G1_MSM_BASE_GAS_FEE);
39    if required_gas > gas_limit {
40        return Err(PrecompileHalt::OutOfGas);
41    }
42
43    let mut valid_pairs_iter = input_chunks.map(|pair| {
44        let (padded_g1, scalar_bytes) = pair.split_at(PADDED_G1_LENGTH);
45
46        // Remove padding from G1 point - this validates padding format
47        let [x, y] = remove_g1_padding(padded_g1)?;
48        let scalar_array: [u8; SCALAR_LENGTH] = scalar_bytes.try_into().unwrap();
49
50        let point: G1Point = (*x, *y);
51        Ok((point, scalar_array))
52    });
53
54    let unpadded_result = crypto().bls12_381_g1_msm(&mut valid_pairs_iter)?;
55
56    // Pad the result for EVM compatibility
57    let padded_result = pad_g1_point(&unpadded_result);
58
59    Ok(EthPrecompileOutput::new(required_gas, padded_result.into()))
60}
61
62#[cfg(test)]
63mod test {
64    use super::*;
65    use primitives::{hex, Bytes};
66
67    #[test]
68    fn bls_g1multiexp_g1_not_on_curve_but_in_subgroup() {
69        let input = Bytes::from(hex!("000000000000000000000000000000000a2833e497b38ee3ca5c62828bf4887a9f940c9e426c7890a759c20f248c23a7210d2432f4c98a514e524b5184a0ddac00000000000000000000000000000000150772d56bf9509469f9ebcd6e47570429fd31b0e262b66d512e245c38ec37255529f2271fd70066473e393a8bead0c30000000000000000000000000000000000000000000000000000000000000000"));
70        let fail = g1_msm(&input, G1_MSM_BASE_GAS_FEE);
71        assert_eq!(fail, Err(PrecompileHalt::Bls12381G1NotOnCurve));
72    }
73}
revm_precompile/bls12_381/g1_msm.rs

revm_precompile/bls12_381/
g1_msm.rs
