def _extract_lengths(data):
# extract argument lengths
base_length_bytes = pad32r(data[:32])
base_length = big_endian_to_int(base_length_bytes)
exponent_length_bytes = pad32r(data[32:64])
exponent_length = big_endian_to_int(exponent_length_bytes)
modulus_length_bytes = pad32r(data[64:96])
modulus_length = big_endian_to_int(modulus_length_bytes)
return base_length, exponent_length, modulus_length
def _ecmull(data):
x_bytes = pad32r(data[:32])
y_bytes = pad32r(data[32:64])
m_bytes = pad32r(data[64:96])
x = big_endian_to_int(x_bytes)
y = big_endian_to_int(y_bytes)
m = big_endian_to_int(m_bytes)
p = validate_point(x, y)
result = bn128.normalize(bn128.multiply(p, m))
return result
def _ecadd(data):
x1_bytes = pad32r(data[:32])
y1_bytes = pad32r(data[32:64])
x2_bytes = pad32r(data[64:96])
y2_bytes = pad32r(data[96:128])
x1 = big_endian_to_int(x1_bytes)
y1 = big_endian_to_int(y1_bytes)
x2 = big_endian_to_int(x2_bytes)
y2 = big_endian_to_int(y2_bytes)
p1 = validate_point(x1, y1)
p2 = validate_point(x2, y2)
result = bn128.normalize(bn128.add(p1, p2))
return result
def ecrecover(computation):
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 test_pad_32r(value, expected):
assert pad32r(value) == expected