revm_precompile/bls12_381/
g1_msm.rs

1//! BLS12-381 G1 msm precompile. More details in [`g1_msm`]
2use crate::bls12_381::utils::{pad_g1_point, remove_g1_padding};
3use crate::bls12_381::G1Point;
4use crate::bls12_381_const::{
5    DISCOUNT_TABLE_G1_MSM, G1_MSM_ADDRESS, G1_MSM_BASE_GAS_FEE, G1_MSM_INPUT_LENGTH,
6    PADDED_G1_LENGTH, SCALAR_LENGTH,
7};
8use crate::bls12_381_utils::msm_required_gas;
9use crate::{crypto, PrecompileError, PrecompileOutput, PrecompileResult, PrecompileWithAddress};
10
11/// [EIP-2537](https://eips.ethereum.org/EIPS/eip-2537#specification) BLS12_G1MSM precompile.
12pub const PRECOMPILE: PrecompileWithAddress = PrecompileWithAddress(G1_MSM_ADDRESS, g1_msm);
13
14/// Implements EIP-2537 G1MSM precompile.
15/// G1 multi-scalar-multiplication call expects `160*k` bytes as an input that is interpreted
16/// as byte concatenation of `k` slices each of them being a byte concatenation
17/// of encoding of G1 point (`128` bytes) and encoding of a scalar value (`32`
18/// bytes).
19/// Output is an encoding of multi-scalar-multiplication operation result - single G1
20/// point (`128` bytes).
21/// See also: <https://eips.ethereum.org/EIPS/eip-2537#abi-for-g1-multiexponentiation>
22pub fn g1_msm(input: &[u8], gas_limit: u64) -> PrecompileResult {
23    let input_len = input.len();
24    if input_len == 0 || !input_len.is_multiple_of(G1_MSM_INPUT_LENGTH) {
25        return Err(PrecompileError::Other(format!(
26            "G1MSM input length should be multiple of {G1_MSM_INPUT_LENGTH}, was {input_len}",
27        )));
28    }
29
30    let k = input_len / G1_MSM_INPUT_LENGTH;
31    let required_gas = msm_required_gas(k, &DISCOUNT_TABLE_G1_MSM, G1_MSM_BASE_GAS_FEE);
32    if required_gas > gas_limit {
33        return Err(PrecompileError::OutOfGas);
34    }
35
36    let mut valid_pairs_iter = (0..k).map(|i| {
37        let start = i * G1_MSM_INPUT_LENGTH;
38        let padded_g1 = &input[start..start + PADDED_G1_LENGTH];
39        let scalar_bytes = &input[start + PADDED_G1_LENGTH..start + G1_MSM_INPUT_LENGTH];
40
41        // Remove padding from G1 point - this validates padding format
42        let [x, y] = remove_g1_padding(padded_g1)?;
43        let scalar_array: [u8; SCALAR_LENGTH] = scalar_bytes.try_into().unwrap();
44
45        let point: G1Point = (*x, *y);
46        Ok((point, scalar_array))
47    });
48
49    let unpadded_result = crypto().bls12_381_g1_msm(&mut valid_pairs_iter)?;
50
51    // Pad the result for EVM compatibility
52    let padded_result = pad_g1_point(&unpadded_result);
53
54    Ok(PrecompileOutput::new(required_gas, padded_result.into()))
55}
56
57#[cfg(test)]
58mod test {
59    use super::*;
60    use primitives::{hex, Bytes};
61
62    #[test]
63    fn bls_g1multiexp_g1_not_on_curve_but_in_subgroup() {
64        let input = Bytes::from(hex!("000000000000000000000000000000000a2833e497b38ee3ca5c62828bf4887a9f940c9e426c7890a759c20f248c23a7210d2432f4c98a514e524b5184a0ddac00000000000000000000000000000000150772d56bf9509469f9ebcd6e47570429fd31b0e262b66d512e245c38ec37255529f2271fd70066473e393a8bead0c30000000000000000000000000000000000000000000000000000000000000000"));
65        let fail = g1_msm(&input, G1_MSM_BASE_GAS_FEE);
66        assert_eq!(
67            fail,
68            Err(PrecompileError::Other(
69                "Element not on G1 curve".to_string()
70            ))
71        );
72    }
73}
revm_precompile/bls12_381/g1_msm.rs

revm_precompile/bls12_381/
g1_msm.rs
