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chore: use EncodedPoint to decode uncompressed public key #2736

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Merged
rakita merged 4 commits into from
Jul 23, 2025
Merged

chore: use EncodedPoint to decode uncompressed public key #2736

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8b8bfcf
use encoded_point
kevaundray Jul 19, 2025
bacdd53
clippy
kevaundray Jul 19, 2025
a849d68
decode using untagged bytes
kevaundray Jul 19, 2025
b2733eb
Merge branch 'main' into kw/secp256r1-sec1-encoding
kevaundray Jul 21, 2025
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22 changes: 11 additions & 11 deletions crates/precompile/src/secp256r1.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,10 @@
use crate::{
u64_to_address, PrecompileError, PrecompileOutput, PrecompileResult, PrecompileWithAddress,
};
use p256::ecdsa::{signature::hazmat::PrehashVerifier, Signature, VerifyingKey};
use p256::{
ecdsa::{signature::hazmat::PrehashVerifier, Signature, VerifyingKey},
EncodedPoint,
};
use primitives::{alloy_primitives::B512, Bytes, B256};

/// Address of secp256r1 precompile.
Expand Down Expand Up @@ -84,21 +87,18 @@ pub fn verify_impl(input: &[u8]) -> Option<()> {
// r, s: signature
let sig = <&B512>::try_from(&input[32..96]).unwrap();
// x, y: public key
let pk = &input[96..160];

// Prepend 0x04 to the public key: uncompressed form
let mut uncompressed_pk = [0u8; 65];
uncompressed_pk[0] = 0x04;
uncompressed_pk[1..].copy_from_slice(pk);
Comment on lines -89 to -92
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@kevaundray kevaundray Jul 19, 2025 •
edited
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The 0x04 was because of from_sec1_bytes -- using untagged_bytes means we don't need to do this and can avoid this allocation plus the validation of 0x04 tag

let pk = <&B512>::try_from(&input[96..160]).unwrap();

verify_signature(msg.0, sig.0, uncompressed_pk)
verify_signature(msg.0, sig.0, pk.0)
}

fn verify_signature(msg: [u8; 32], sig: [u8; 64], uncompressed_pk: [u8; 65]) -> Option<()> {
fn verify_signature(msg: [u8; 32], sig: [u8; 64], pk: [u8; 64]) -> Option<()> {
// Can fail only if the input is not exact length.
let signature = Signature::from_slice(&sig).ok()?;
// Can fail if the input is not valid, so we have to propagate the error.
let public_key = VerifyingKey::from_sec1_bytes(&uncompressed_pk).ok()?;
// Decode the public key bytes (x,y coordinates) using EncodedPoint
let encoded_point = EncodedPoint::from_untagged_bytes(&pk.into());
// Create VerifyingKey from the encoded point
let public_key = VerifyingKey::from_encoded_point(&encoded_point).ok()?;

public_key.verify_prehash(&msg, &signature).ok()
}
Expand Down
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