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213 | @pytest.mark.repricing
@pytest.mark.parametrize("num_rounds", [1, 6, 12, 24])
def test_blake2f_uncachable(
benchmark_test: BenchmarkTestFiller,
pre: Alloc,
fork: Fork,
gas_benchmark_value: int,
tx_gas_limit: int,
num_rounds: int,
) -> None:
"""
Benchmark BLAKE2F with unique input per call.
Each iteration writes the 64-byte output back to offset 4 in
memory, overwriting the h[] state so every call receives a
distinct input, avoiding precompile result caching in
clients.
"""
precompile_address = Blake2bSpec.BLAKE2_PRECOMPILE_ADDRESS
if precompile_address not in fork.precompiles():
pytest.skip("Precompile not enabled")
intrinsic_gas_calculator = fork.transaction_intrinsic_cost_calculator()
# BLAKE2F costs num_rounds gas.
gsc = fork.gas_costs()
precompile_cost = (
num_rounds * gsc.PRECOMPILE_BLAKE2F_PER_ROUND
) + gsc.PRECOMPILE_BLAKE2F_BASE
attack_block = Op.POP(
Op.STATICCALL(
gas=Op.GAS,
address=precompile_address,
args_size=Op.CALLDATASIZE,
# override the h state
ret_offset=4,
ret_size=64,
# gas accounting
address_warm=True,
inner_call_cost=precompile_cost,
),
)
# rounds: data[0:4] 4 bytes
# h: data[4:68] 64 bytes
# m: data[68:196] 128 bytes
# t: data[196:212] 16 bytes
# f: data[212:213] 1 byte
setup = Op.CALLDATACOPY(
0,
0,
Op.CALLDATASIZE,
# gas accounting
data_size=213,
old_memory_size=0,
new_memory_size=213,
)
setup_cost = setup.gas_cost(fork)
loop = WhileGas(
body=attack_block,
fork=fork,
)
code = setup + loop
attack_contract_address = pre.deploy_contract(code=code)
iteration_cost = loop.gas_cost(fork)
base_calldata = Blake2bInput(
rounds=num_rounds, f=True
).create_blake2b_tx_data()
txs: list[Transaction] = []
remaining_gas = gas_benchmark_value
rng = random.Random(42)
expected_opcode_count = 0
while remaining_gas > 0:
per_tx_gas = min(tx_gas_limit, remaining_gas)
h_state = rng.randbytes(64)
calldata = Bytes(
base_calldata[:4] # rounds
+ h_state # h
+ base_calldata[68:] # m, t, f
)
intrinsic = intrinsic_gas_calculator(
calldata=calldata,
return_cost_deducted_prior_execution=True,
)
gas_for_loop = per_tx_gas - intrinsic - setup_cost
if gas_for_loop < iteration_cost:
break
expected_opcode_count += gas_for_loop // iteration_cost
txs.append(
Transaction(
to=attack_contract_address,
sender=pre.fund_eoa(),
gas_limit=per_tx_gas,
data=calldata,
)
)
remaining_gas -= per_tx_gas
assert len(txs) != 0, "No transactions were added to the test."
benchmark_test(
target_opcode=Op.STATICCALL,
skip_gas_used_validation=True,
expected_receipt_status=1,
blocks=[Block(txs=txs)],
expected_opcode_count=expected_opcode_count,
)
|