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fix: ec_recover when point at infinity #958

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Sep 18, 2024
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29 changes: 21 additions & 8 deletions crates/evm/src/precompiles/ec_recover.cairo
Original file line number Diff line number Diff line change
@@ -1,13 +1,18 @@
use core::starknet::secp256_trait::{recover_public_key, Signature};
use core::starknet::secp256_trait::{
Signature, recover_public_key, Secp256PointTrait, is_valid_signature
};
use core::starknet::secp256_trait::{Secp256Trait};
use core::starknet::{
EthAddress, eth_signature::{public_key_point_to_eth_address}, secp256k1::{Secp256k1Point}
EthAddress, eth_signature::{public_key_point_to_eth_address}, secp256k1::{Secp256k1Point},
SyscallResultTrait
};
use core::traits::Into;
use evm::errors::EVMError;
use evm::precompiles::Precompile;
use utils::helpers::U8SpanExTrait;
use utils::helpers::{ToBytes, FromBytes};
use utils::traits::BoolIntoNumeric;
use utils::traits::EthAddressIntoU256;
use utils::traits::{NumericIntoBool, BoolIntoNumeric};

const EC_RECOVER_PRECOMPILE_GAS_COST: u64 = 3000;

Expand All @@ -20,6 +25,8 @@ pub impl EcRecover of Precompile {
fn exec(input: Span<u8>) -> Result<(u64, Span<u8>), EVMError> {
let gas = EC_RECOVER_PRECOMPILE_GAS_COST;

// Pad the input to 128 bytes to avoid out-of-bounds accesses
let input = input.pad_right_with_zeroes(128);
let message_hash = input.slice(0, 32);
let message_hash = match message_hash.from_be_bytes() {
Option::Some(message_hash) => message_hash,
Expand All @@ -29,12 +36,11 @@ pub impl EcRecover of Precompile {
let v: Option<u256> = input.slice(32, 32).from_be_bytes();
let y_parity = match v {
Option::Some(v) => {
let y_parity = v - 27;
if (y_parity == 0 || y_parity == 1) {
y_parity == 1
} else {
if !(v == 27 || v == 28) {
return Result::Ok((gas, [].span()));
}
let y_parity = v - 27; //won't overflow because v is 27 or 28
y_parity.into()
},
Option::None => { return Result::Ok((gas, [].span())); }
};
Expand All @@ -55,7 +61,14 @@ pub impl EcRecover of Precompile {

let recovered_public_key =
match recover_public_key::<Secp256k1Point>(message_hash, signature) {
Option::Some(public_key_point) => public_key_point,
Option::Some(public_key_point) => {
// EVM spec requires that the public key is not the point at infinity
let (x, y) = public_key_point.get_coordinates().unwrap_syscall();
if (x == 0 && y == 0) {
return Result::Ok((gas, [].span()));
}
public_key_point
},
Option::None => { return Result::Ok((gas, [].span())); }
};

Expand Down
7 changes: 7 additions & 0 deletions crates/utils/src/traits.cairo
Original file line number Diff line number Diff line change
Expand Up @@ -45,6 +45,13 @@ pub impl BoolIntoNumeric<T, +Zero<T>, +One<T>> of Into<bool, T> {
}
}

pub impl NumericIntoBool<T, +Drop<T>, +Zero<T>, +One<T>, +PartialEq<T>> of Into<T, bool> {
#[inline(always)]
fn into(self: T) -> bool {
self != Zero::<T>::zero()
}
}

pub impl EthAddressIntoU256 of Into<EthAddress, u256> {
fn into(self: EthAddress) -> u256 {
let intermediate: felt252 = self.into();
Expand Down
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