def _modexp(data):
base_length, exponent_length, modulus_length = _extract_lengths(data)
if base_length == 0:
return 0
elif modulus_length == 0:
return 0
# compute start:end indexes
base_end_idx = 96 + base_length
exponent_end_idx = base_end_idx + exponent_length
modulus_end_dx = exponent_end_idx + modulus_length
# extract arguments
modulus_bytes = zpad_right(
data[exponent_end_idx:modulus_end_dx],
to_size=modulus_length,
)
modulus = big_endian_to_int(modulus_bytes)
if modulus == 0:
return 0
base_bytes = zpad_right(data[96:base_end_idx], to_size=base_length)
base = big_endian_to_int(base_bytes)
exponent_bytes = zpad_right(
data[base_end_idx:exponent_end_idx],
to_size=exponent_length,
)
exponent = big_endian_to_int(exponent_bytes)
print('base', base, 'exponent', exponent, 'modulus', modulus)
result = pow(base, exponent, modulus)
return result
def _compute_adjusted_exponent_length(exponent_length,
first_32_exponent_bytes):
exponent = big_endian_to_int(first_32_exponent_bytes)
if exponent_length <= 32 and exponent == 0:
return 0
elif exponent_length <= 32:
return get_highest_bit_index(exponent)
else:
first_32_bytes_as_int = big_endian_to_int(first_32_exponent_bytes)
return (8 * (exponent_length - 32) +
get_highest_bit_index(first_32_bytes_as_int))
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 check_pow(block_number: int, mining_hash: Hash32, mix_hash: Hash32,
nonce: bytes, difficulty: int) -> None:
validate_length(mix_hash, 32, title="Mix Hash")
validate_length(mining_hash, 32, title="Mining Hash")
validate_length(nonce, 8, title="POW Nonce")
cache = get_cache(block_number)
mining_output = hashimoto_light(block_number, cache, mining_hash,
big_endian_to_int(nonce))
if mining_output[b'mix digest'] != mix_hash:
raise ValidationError("mix hash mismatch; {0} != {1}".format(
encode_hex(mining_output[b'mix digest']), encode_hex(mix_hash)))
result = big_endian_to_int(mining_output[b'result'])
validate_lte(result, 2**256 // difficulty, title="POW Difficulty")
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 mine_pow_nonce(block_number: int, mining_hash: Hash32,
difficulty: int) -> Tuple[bytes, bytes]:
cache = get_cache(block_number)
for nonce in range(MAX_TEST_MINE_ATTEMPTS):
mining_output = hashimoto_light(block_number, cache, mining_hash,
nonce)
result = big_endian_to_int(mining_output[b'result'])
result_cap = 2**256 // difficulty
if result <= result_cap:
return nonce.to_bytes(8, 'big'), mining_output[b'mix digest']
raise Exception("Too many attempts at POW mining, giving up")
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 _extract_point(data_slice):
x1_bytes = data_slice[:32]
y1_bytes = data_slice[32:64]
x2_i_bytes = data_slice[64:96]
x2_r_bytes = data_slice[96:128]
y2_i_bytes = data_slice[128:160]
y2_r_bytes = data_slice[160:192]
x1 = big_endian_to_int(x1_bytes)
y1 = big_endian_to_int(y1_bytes)
x2_i = big_endian_to_int(x2_i_bytes)
x2_r = big_endian_to_int(x2_r_bytes)
y2_i = big_endian_to_int(y2_i_bytes)
y2_r = big_endian_to_int(y2_r_bytes)
return x1, y1, x2_i, x2_r, y2_i, y2_r
def _pop(self, num_items, type_hint):
for _ in range(num_items):
if type_hint == constants.UINT256:
value = self.values.pop()
if isinstance(value, int):
yield value
else:
yield big_endian_to_int(value)
elif type_hint == constants.BYTES:
value = self.values.pop()
if isinstance(value, bytes):
yield value
else:
yield int_to_big_endian(value)
elif type_hint == constants.ANY:
yield self.values.pop()
else:
raise TypeError(
"Unknown type_hint: {0}. Must be one of {1}".format(
type_hint,
", ".join((constants.UINT256, constants.BYTES)),
)
)