revm_precompile/
kzg_point_evaluation.rs

1use crate::{Address, PrecompileError, PrecompileOutput, PrecompileResult, PrecompileWithAddress};
2cfg_if::cfg_if! {
3    if #[cfg(feature = "c-kzg")] {
4        use c_kzg::{Bytes32, Bytes48, KzgProof};
5    } else if #[cfg(feature = "kzg-rs")] {
6        use kzg_rs::{Bytes32, Bytes48, KzgProof};
7    }
8}
9use primitives::{hex_literal::hex, Bytes};
10use sha2::{Digest, Sha256};
11
12pub const POINT_EVALUATION: PrecompileWithAddress = PrecompileWithAddress(ADDRESS, run);
13
14pub const ADDRESS: Address = crate::u64_to_address(0x0A);
15pub const GAS_COST: u64 = 50_000;
16pub const VERSIONED_HASH_VERSION_KZG: u8 = 0x01;
17
18/// `U256(FIELD_ELEMENTS_PER_BLOB).to_be_bytes() ++ BLS_MODULUS.to_bytes32()`
19pub const RETURN_VALUE: &[u8; 64] = &hex!(
20    "0000000000000000000000000000000000000000000000000000000000001000"
21    "73eda753299d7d483339d80809a1d80553bda402fffe5bfeffffffff00000001"
22);
23
24/// Run kzg point evaluation precompile.
25///
26/// The Env has the KZGSettings that is needed for evaluation.
27///
28/// The input is encoded as follows:
29/// | versioned_hash |  z  |  y  | commitment | proof |
30/// |     32         | 32  | 32  |     48     |   48  |
31/// with z and y being padded 32 byte big endian values
32pub fn run(input: &Bytes, gas_limit: u64) -> PrecompileResult {
33    if gas_limit < GAS_COST {
34        return Err(PrecompileError::OutOfGas);
35    }
36
37    // Verify input length.
38    if input.len() != 192 {
39        return Err(PrecompileError::BlobInvalidInputLength);
40    }
41
42    // Verify commitment matches versioned_hash
43    let versioned_hash = &input[..32];
44    let commitment = &input[96..144];
45    if kzg_to_versioned_hash(commitment) != versioned_hash {
46        return Err(PrecompileError::BlobMismatchedVersion);
47    }
48
49    // Verify KZG proof with z and y in big endian format
50    let commitment = as_bytes48(commitment);
51    let z = as_bytes32(&input[32..64]);
52    let y = as_bytes32(&input[64..96]);
53    let proof = as_bytes48(&input[144..192]);
54    if !verify_kzg_proof(commitment, z, y, proof) {
55        return Err(PrecompileError::BlobVerifyKzgProofFailed);
56    }
57
58    // Return FIELD_ELEMENTS_PER_BLOB and BLS_MODULUS as padded 32 byte big endian values
59    Ok(PrecompileOutput::new(GAS_COST, RETURN_VALUE.into()))
60}
61
62/// `VERSIONED_HASH_VERSION_KZG ++ sha256(commitment)[1..]`
63#[inline]
64pub fn kzg_to_versioned_hash(commitment: &[u8]) -> [u8; 32] {
65    let mut hash: [u8; 32] = Sha256::digest(commitment).into();
66    hash[0] = VERSIONED_HASH_VERSION_KZG;
67    hash
68}
69
70#[inline]
71pub fn verify_kzg_proof(commitment: &Bytes48, z: &Bytes32, y: &Bytes32, proof: &Bytes48) -> bool {
72    cfg_if::cfg_if! {
73        if #[cfg(feature = "c-kzg")] {
74            let kzg_settings = c_kzg::ethereum_kzg_settings();
75        } else if #[cfg(feature = "kzg-rs")] {
76            let env = kzg_rs::EnvKzgSettings::default();
77            let kzg_settings = env.get();
78        }
79    }
80    KzgProof::verify_kzg_proof(commitment, z, y, proof, kzg_settings).unwrap_or(false)
81}
82
83#[inline]
84#[track_caller]
85pub fn as_array<const N: usize>(bytes: &[u8]) -> &[u8; N] {
86    bytes.try_into().expect("slice with incorrect length")
87}
88
89#[inline]
90#[track_caller]
91pub fn as_bytes32(bytes: &[u8]) -> &Bytes32 {
92    // SAFETY: `#[repr(C)] Bytes32([u8; 32])`
93    unsafe { &*as_array::<32>(bytes).as_ptr().cast() }
94}
95
96#[inline]
97#[track_caller]
98pub fn as_bytes48(bytes: &[u8]) -> &Bytes48 {
99    // SAFETY: `#[repr(C)] Bytes48([u8; 48])`
100    unsafe { &*as_array::<48>(bytes).as_ptr().cast() }
101}
102
103#[cfg(test)]
104mod tests {
105    use super::*;
106
107    #[test]
108    fn basic_test() {
109        // Test data from: https://github.com/ethereum/c-kzg-4844/blob/main/tests/verify_kzg_proof/kzg-mainnet/verify_kzg_proof_case_correct_proof_31ebd010e6098750/data.yaml
110
111        let commitment = hex!("8f59a8d2a1a625a17f3fea0fe5eb8c896db3764f3185481bc22f91b4aaffcca25f26936857bc3a7c2539ea8ec3a952b7").to_vec();
112        let mut versioned_hash = Sha256::digest(&commitment).to_vec();
113        versioned_hash[0] = VERSIONED_HASH_VERSION_KZG;
114        let z = hex!("73eda753299d7d483339d80809a1d80553bda402fffe5bfeffffffff00000000").to_vec();
115        let y = hex!("1522a4a7f34e1ea350ae07c29c96c7e79655aa926122e95fe69fcbd932ca49e9").to_vec();
116        let proof = hex!("a62ad71d14c5719385c0686f1871430475bf3a00f0aa3f7b8dd99a9abc2160744faf0070725e00b60ad9a026a15b1a8c").to_vec();
117
118        let input = [versioned_hash, z, y, commitment, proof].concat();
119
120        let expected_output = hex!("000000000000000000000000000000000000000000000000000000000000100073eda753299d7d483339d80809a1d80553bda402fffe5bfeffffffff00000001");
121        let gas = 50000;
122        let output = run(&input.into(), gas).unwrap();
123        assert_eq!(output.gas_used, gas);
124        assert_eq!(output.bytes[..], expected_output);
125    }
126}
revm_precompile/kzg_point_evaluation.rs

revm_precompile/
kzg_point_evaluation.rs
