def ecrecover(computation: BaseComputation) -> BaseComputation:
computation.consume_gas(constants.GAS_ECRECOVER, reason="ECRecover Precompile")
raw_message_hash = computation.msg.data[:32]
message_hash = pad32r(raw_message_hash)
v_bytes = pad32r(computation.msg.data[32:64])
v = big_endian_to_int(v_bytes)
r_bytes = pad32r(computation.msg.data[64:96])
r = big_endian_to_int(r_bytes)
s_bytes = pad32r(computation.msg.data[96:128])
s = big_endian_to_int(s_bytes)
try:
validate_lt_secpk1n(r, title="ECRecover: R")
validate_lt_secpk1n(s, title="ECRecover: S")
validate_lte(v, 28, title="ECRecover: V")
validate_gte(v, 27, title="ECRecover: V")
except ValidationError:
return computation
canonical_v = v - 27
try:
signature = keys.Signature(vrs=(canonical_v, r, s))
public_key = signature.recover_public_key_from_msg_hash(message_hash)
except BadSignature:
return computation
address = public_key.to_canonical_address()
padded_address = pad32(address)
computation.output = padded_address
return computation
def validate(self) -> None:
validate_uint256(self.nonce, title="Transaction.nonce")
validate_uint256(self.gas_price, title="Transaction.gas_price")
validate_uint256(self.gas, title="Transaction.gas")
if self.to != CREATE_CONTRACT_ADDRESS:
validate_canonical_address(self.to, title="Transaction.to")
validate_uint256(self.value, title="Transaction.value")
validate_is_bytes(self.data, title="Transaction.data")
validate_uint256(self.v, title="Transaction.v")
validate_uint256(self.r, title="Transaction.r")
validate_uint256(self.s, title="Transaction.s")
validate_lt_secpk1n(self.r, title="Transaction.r")
validate_gte(self.r, minimum=1, title="Transaction.r")
validate_lt_secpk1n(self.s, title="Transaction.s")
validate_gte(self.s, minimum=1, title="Transaction.s")
validate_gte(self.v, minimum=self.v_min, title="Transaction.v")
validate_lte(self.v, maximum=self.v_max, title="Transaction.v")
super().validate()
def test_validate_lt_secpk1n(value, is_valid):
if is_valid:
validate_lt_secpk1n(value)
else:
with pytest.raises(ValidationError):
validate_lt_secpk1n(value)
