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fix(fvm): accept malleable secp256k1 signatures (per EVM, etc.) (backport v2) #2158

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Merged
Stebalien merged 1 commit into from
Apr 15, 2025
Merged

fix(fvm): accept malleable secp256k1 signatures (per EVM, etc.) (backport v2) #2158

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1 change: 1 addition & 0 deletions Cargo.lock
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1 change: 1 addition & 0 deletions shared/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,7 @@ rand_chacha = "0.3.1"
serde_json = "1.0.140"
multihash = { workspace = true }
multihash-codetable = { workspace = true, features = ["sha2", "sha3", "ripemd"] }
hex = "0.4.3"

[features]
default = []
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43 changes: 39 additions & 4 deletions shared/src/crypto/signature.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -243,14 +243,22 @@ pub mod ops {
signature: &[u8; SECP_SIG_LEN],
) -> Result<[u8; SECP_PUB_LEN], Error> {
// Extract recovery ID from the last byte
let recovery_id = RecoveryId::try_from(signature[64])
.map_err(|e| Error::InvalidRecovery(format!("Invalid recovery ID: {}", e)))?;
let mut rec_byte = signature[64];

// Create signature from the first 64 bytes
let sig_bytes = signature[..64].into();
let signature = EcdsaSignature::from_bytes(sig_bytes)
let mut signature = EcdsaSignature::from_slice(&signature[..64])
.map_err(|e| Error::SigningError(format!("Invalid signature: {}", e)))?;

// Normalize the signature & recovery byte (required for Ethereum compatibility).
if let Some(normalized) = signature.normalize_s() {
signature = normalized;
rec_byte ^= 1;
}

// Extract recovery ID from the last byte
let recovery_id = RecoveryId::try_from(rec_byte)
.map_err(|e| Error::InvalidRecovery(format!("Invalid recovery ID: {}", e)))?;

// Recover the verifying key
let pk = VerifyingKey::recover_from_prehash(&hash[..], &signature, recovery_id)
.map_err(|e| Error::InvalidRecovery(format!("Failed to recover key: {}", e)))?;
Expand All @@ -274,6 +282,8 @@ pub mod ops {
mod tests {
use bls_signatures::{PrivateKey, Serialize, Signature as BlsSignature};
use k256::ecdsa::SigningKey;
use multihash_codetable::Code;
use multihash_codetable::MultihashDigest;
use rand::{Rng, SeedableRng};
use rand_chacha::ChaCha8Rng;

Expand Down Expand Up @@ -349,6 +359,31 @@ mod tests {
assert_eq!(target_key, &recovered_key[..]);
}

// Tests malleability.
#[test]
fn secp_ecrecover_testvector() {
let hash: [u8; 32] =
hex::decode("18c547e4f7b0f325ad1e56f57e26c745b09a3e503d86e00e5255ff7f715d3d1c")
.unwrap()
.try_into()
.unwrap();
let recbyte = 0x1c - 27;
let r = hex::decode("73b1693892219d736caba55bdb67216e485557ea6b6af75f37096c9aa6a5a75f")
.unwrap();
let s = hex::decode("eeb940b1d03b21e36b0e47e79769f095fe2ab855bd91e3a38756b7d75a9c4549")
.unwrap();
let expected = hex::decode("a94f5374fce5edbc8e2a8697c15331677e6ebf0b").unwrap();

let mut sig = [0u8; SECP_SIG_LEN];
sig[..32].copy_from_slice(&r);
sig[32..64].copy_from_slice(&s);
sig[64] = recbyte;

let recovered = recover_secp_public_key(&hash, &sig).unwrap();
let hashed = Code::Keccak256.digest(&recovered[1..]);
assert_eq!(expected, &hashed.digest()[12..]);
}

#[test]
fn secp_ecrecover() {
let rng = &mut ChaCha8Rng::seed_from_u64(8);
Expand Down
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