def bob_deposit(
zeth_client: MixerClient,
mk_tree: MerkleTree,
bob_eth_address: str,
keystore: mock.KeyStore,
tx_value: Optional[EtherValue] = None) -> contracts.MixResult:
print(
f"=== Bob deposits {BOB_DEPOSIT_ETH} ETH for himself and splits into " +
f"note1: {BOB_SPLIT_1_ETH}ETH, note2: {BOB_SPLIT_2_ETH}ETH ===")
bob_js_keypair = keystore["Bob"]
bob_addr = keystore["Bob"].addr_pk
outputs = [
(bob_addr, EtherValue(BOB_SPLIT_1_ETH)),
(bob_addr, EtherValue(BOB_SPLIT_2_ETH)),
]
tx_hash = zeth_client.deposit(
mk_tree,
bob_js_keypair,
bob_eth_address,
None,
EtherValue(BOB_DEPOSIT_ETH),
outputs,
tx_value)
return wait_for_tx_update_mk_tree(zeth_client, mk_tree, tx_hash)
def bob_to_charlie(
zeth_client: MixerClient,
mk_tree: MerkleTree,
input1: Tuple[int, ZethNote],
bob_eth_address: str,
keystore: mock.KeyStore) -> contracts.MixResult:
print(
f"=== Bob transfers {BOB_TO_CHARLIE_ETH}ETH to Charlie from his funds " +
"on the mixer ===")
bob_ask = keystore["Bob"].addr_sk.a_sk
charlie_addr = keystore["Charlie"].addr_pk
bob_addr = keystore["Bob"].addr_pk
# Coin for Bob (change)
output0 = (bob_addr, EtherValue(BOB_TO_CHARLIE_ETH))
# Coin for Charlie
output1 = (charlie_addr, EtherValue(BOB_TO_CHARLIE_CHANGE_ETH))
# Send the tx
tx_hash = zeth_client.joinsplit(
mk_tree,
OwnershipKeyPair(bob_ask, bob_addr.a_pk),
bob_eth_address,
None,
[input1],
[output0, output1],
EtherValue(0),
EtherValue(0),
EtherValue(1, 'wei'))
return wait_for_tx_update_mk_tree(zeth_client, mk_tree, tx_hash)
def deploy(
ctx: Context,
eth_addr: Optional[str],
eth_private_key: Optional[str],
instance_out: str,
token_address: str,
deploy_gas: Optional[int]) -> None:
"""
Deploy the zeth contracts and record the instantiation details.
"""
eth_address = load_eth_address(eth_addr)
eth_private_key_data = load_eth_private_key(eth_private_key)
client_ctx = ctx.obj
web3 = open_web3_from_ctx(client_ctx)
print(f"deploy: eth_address={eth_address}")
print(f"deploy: instance_out={instance_out}")
print(f"deploy: token_address={token_address}")
token_instance_desc = get_erc20_instance_description(token_address) \
if token_address else None
prover_client = create_prover_client(client_ctx)
_zeth_client, mixer_instance_desc = MixerClient.deploy(
web3,
prover_client,
eth_address,
eth_private_key_data,
token_address,
deploy_gas)
mixer_desc = MixerDescription(mixer_instance_desc, token_instance_desc)
write_mixer_description(instance_out, mixer_desc)
def charlie_withdraw(
zeth_client: MixerClient,
mk_tree: MerkleTree,
input1: Tuple[int, ZethNote],
charlie_eth_address: str,
keystore: mock.KeyStore) -> contracts.MixResult:
print(
f" === Charlie withdraws {CHARLIE_WITHDRAW_ETH}ETH from his funds " +
"on the Mixer ===")
charlie_pk = keystore["Charlie"].addr_pk
charlie_apk = charlie_pk.a_pk
charlie_ask = keystore["Charlie"].addr_sk.a_sk
charlie_ownership_key = \
OwnershipKeyPair(charlie_ask, charlie_apk)
tx_hash = zeth_client.joinsplit(
mk_tree,
charlie_ownership_key,
charlie_eth_address,
None,
[input1],
[(charlie_pk, EtherValue(CHARLIE_WITHDRAW_CHANGE_ETH))],
EtherValue(0),
EtherValue(CHARLIE_WITHDRAW_ETH),
EtherValue(1, 'wei'))
return wait_for_tx_update_mk_tree(zeth_client, mk_tree, tx_hash)
def get_mix_parameters_components(
zeth_client: MixerClient,
prover_client: ProverClient,
mk_tree: MerkleTree,
sender_ownership_keypair: OwnershipKeyPair,
inputs: List[Tuple[int, ZethNote]],
outputs: List[Tuple[ZethAddressPub, EtherValue]],
v_in: EtherValue,
v_out: EtherValue,
compute_h_sig_cb: Optional[ComputeHSigCB] = None
) -> Tuple[ZethNote, ZethNote, ExtendedProof, List[int], JoinsplitSigKeyPair]:
"""
Manually create the components required for MixParameters. The tests below
manipulate these to create custom MixParameters as part of attacks.
"""
mix_call_desc = MixCallDescription(
mk_tree,
sender_ownership_keypair,
inputs,
outputs,
v_in,
v_out,
compute_h_sig_cb)
prover_inputs, signing_keypair = zeth_client.create_prover_inputs(
mix_call_desc)
ext_proof, public_data = prover_client.get_proof(prover_inputs)
return (
prover_inputs.js_outputs[0],
prover_inputs.js_outputs[1],
ext_proof,
public_data,
signing_keypair)
def create_mixer_client(ctx: ClientConfig) -> MixerClient:
"""
Create a MixerClient for an existing deployment.
"""
web3 = open_web3_from_ctx(ctx)
mixer_desc = load_mixer_description_from_ctx(ctx)
mixer_instance = mixer_desc.mixer.instantiate(web3)
return MixerClient.open(web3, ctx.prover_server_endpoint, mixer_instance)
def create_zeth_client_and_mixer_desc(
ctx: ClientConfig) -> Tuple[MixerClient, MixerDescription]:
"""
Create a MixerClient and MixerDescription object, for an existing deployment.
"""
web3 = open_web3_from_ctx(ctx)
mixer_desc = load_mixer_description_from_ctx(ctx)
mixer_instance = mixer_desc.mixer.instantiate(web3)
zeth_client = MixerClient.open(
web3, ctx.prover_server_endpoint, mixer_instance)
return (zeth_client, mixer_desc)
def create_mixer_client_and_mixer_desc(
ctx: ClientConfig,
prover_client: Optional[ProverClient] = None
) -> Tuple[MixerClient, MixerDescription]:
"""
Create a MixerClient and MixerDescription object, for an existing deployment.
"""
web3 = open_web3_from_ctx(ctx)
mixer_desc = load_mixer_description_from_ctx(ctx)
mixer_instance = mixer_desc.mixer.instantiate(web3)
if prover_client is None:
prover_client = create_prover_client(ctx)
prover_config = prover_client.get_configuration()
mixer_client = MixerClient(web3, prover_config, mixer_instance)
return (mixer_client, mixer_desc)
def deploy(ctx: Context, eth_addr: Optional[str],
eth_private_key: Optional[str], instance_out: str,
token_address: Optional[str], permitted_dispatcher: Optional[str],
vk_hash: Optional[str], deploy_gas: Optional[int]) -> None:
"""
Deploy the zeth contracts and record the instantiation details.
"""
eth_address = load_eth_address(eth_addr)
eth_private_key_data = load_eth_private_key(eth_private_key)
client_ctx = ctx.obj
web3 = open_web3_from_ctx(client_ctx)
if bool(permitted_dispatcher) != bool(vk_hash):
raise ClickException(
"Must supply BOTH --permitted-dispatch AND --vk-hash, or NEITHER")
print(f"deploy: eth_address={eth_address}")
print(f"deploy: instance_out={instance_out}")
print(f"deploy: token_address={token_address}")
if permitted_dispatcher:
permitted_dispatcher = load_contract_address(permitted_dispatcher)
print(f"deploy: permitted_dispatcher={permitted_dispatcher}")
print(f"deploy: vk_hash={vk_hash}")
token_instance_desc = get_erc20_instance_description(token_address) \
if token_address else None
prover_client = create_prover_client(client_ctx)
_zeth_client, mixer_instance_desc = MixerClient.deploy(
web3,
prover_client,
eth_address,
eth_private_key_data,
token_address,
permitted_dispatcher=permitted_dispatcher,
vk_hash=vk_hash,
deploy_gas=deploy_gas)
mixer_desc = MixerDescription(mixer=mixer_instance_desc,
token=token_instance_desc,
permitted_dispatcher=permitted_dispatcher,
vk_hash=vk_hash)
write_mixer_description(instance_out, mixer_desc)
def main() -> None:
print("-------------------- Evaluating BaseMixer.sol --------------------")
web3, eth = mock.open_test_web3()
# Ethereum addresses
deployer_eth_address = eth.accounts[0]
zeth_client, _ = MixerClient.deploy(web3, mock.TEST_PROVER_SERVER_ENDPOINT,
deployer_eth_address, None)
mixer_instance = zeth_client.mixer_instance
# We can now call the instance and test its functions.
print("[INFO] 4. Running tests")
result = 0
result += test_assemble_nullifiers(mixer_instance)
result += test_assemble_vpub(mixer_instance)
result += test_assemble_hsig(mixer_instance)
# We do not re-assemble of h_is in the contract
if result == 0:
print("base_mixer tests PASS\n")
def charlie_corrupt_bob_deposit(
zeth_client: MixerClient,
mk_tree: MerkleTree,
bob_eth_address: str,
charlie_eth_address: str,
keystore: mock.KeyStore) -> contracts.MixResult:
"""
Charlie tries to break transaction malleability and corrupt the coins
bob is sending in a transaction
She does so by intercepting bob's transaction and either:
- case 1: replacing the ciphertexts (or sender_eph_pk) by garbage/arbitrary
data
- case 2: replacing the ciphertexts by garbage/arbitrary data and using a
new OT-signature
- case 3: Charlie replays the mix call of Bob, to try to receive the vout
Both attacks should fail,
- case 1: the signature check should fail, else Charlie broke UF-CMA of the
OT signature
- case 2: the h_sig/vk verification should fail, as h_sig is not a function
of vk any longer
- case 3: the signature check should fail, because `msg.sender` will no match
the value used in the mix parameters (Bob's Ethereum Address).
NB. If the adversary were to corrupt the ciphertexts (or the encryption key),
replace the OT-signature by a new one and modify the h_sig accordingly so that
the check on the signature verification (key h_sig/vk) passes, the proof would
not verify, which is why we do not test this case.
"""
print(
f"=== Bob deposits {BOB_DEPOSIT_ETH} ETH for himself and split into " +
f"note1: {BOB_SPLIT_1_ETH}ETH, note2: {BOB_SPLIT_2_ETH}ETH " +
"but Charlie attempts to corrupt the transaction ===")
bob_apk = keystore["Bob"].addr_pk.a_pk
bob_ask = keystore["Bob"].addr_sk.a_sk
tree_depth = mk_tree.depth
mk_root = mk_tree.get_root()
# mk_tree_depth = zeth_client.mk_tree_depth
# mk_root = zeth_client.merkle_root
# Create the JoinSplit dummy inputs for the deposit
input1 = get_dummy_input_and_address(bob_apk)
input2 = get_dummy_input_and_address(bob_apk)
dummy_mk_path = mock.get_dummy_merkle_path(tree_depth)
note1_value = to_zeth_units(EtherValue(BOB_SPLIT_1_ETH))
note2_value = to_zeth_units(EtherValue(BOB_SPLIT_2_ETH))
v_in = to_zeth_units(EtherValue(BOB_DEPOSIT_ETH))
(output_note1, output_note2, proof_json, joinsplit_keypair) = \
zeth_client.get_proof_joinsplit_2_by_2(
mk_root,
input1,
dummy_mk_path,
input2,
dummy_mk_path,
bob_ask, # sender
(bob_apk, note1_value), # recipient1
(bob_apk, note2_value), # recipient2
v_in, # v_in
to_zeth_units(EtherValue(0)) # v_out
)
# Encrypt the coins to bob
pk_bob = keystore["Bob"].addr_pk.k_pk
ciphertexts = encrypt_notes([
(output_note1, pk_bob),
(output_note2, pk_bob)])
# ### ATTACK BLOCK
# Charlie intercepts Bob's deposit, corrupts it and
# sends her transaction before Bob's transaction is accepted
# Case 1: replacing the ciphertexts by garbage/arbitrary data
# Corrupt the ciphertexts
# (another way would have been to overwrite sender_eph_pk)
fake_ciphertext0 = urandom(32)
fake_ciphertext1 = urandom(32)
result_corrupt1 = None
try:
joinsplit_sig_charlie = joinsplit_sign(
joinsplit_keypair,
charlie_eth_address,
ciphertexts,
proof_json)
mix_params = contracts.MixParameters(
proof_json,
joinsplit_keypair.vk,
joinsplit_sig_charlie,
[fake_ciphertext0, fake_ciphertext1])
tx_hash = zeth_client.mix(
mix_params,
charlie_eth_address,
None,
EtherValue(BOB_DEPOSIT_ETH))
result_corrupt1 = \
wait_for_tx_update_mk_tree(zeth_client, mk_tree, tx_hash)
except Exception as e:
print(
"Charlie's first corruption attempt" +
f" successfully rejected! (msg: {e})"
)
assert(result_corrupt1 is None), \
"Charlie managed to corrupt Bob's deposit the first time!"
print("")
# Case 2: replacing the ciphertexts by garbage/arbitrary data and
# using a new OT-signature
# Corrupt the ciphertexts
fake_ciphertext0 = urandom(32)
fake_ciphertext1 = urandom(32)
new_joinsplit_keypair = signing.gen_signing_keypair()
# Sign the primary inputs, sender_eph_pk and the ciphertexts
result_corrupt2 = None
try:
joinsplit_sig_charlie = joinsplit_sign(
new_joinsplit_keypair,
charlie_eth_address,
[fake_ciphertext0, fake_ciphertext1],
proof_json)
mix_params = contracts.MixParameters(
proof_json,
new_joinsplit_keypair.vk,
joinsplit_sig_charlie,
[fake_ciphertext0, fake_ciphertext1])
tx_hash = zeth_client.mix(
mix_params,
charlie_eth_address,
None,
EtherValue(BOB_DEPOSIT_ETH))
result_corrupt2 = \
wait_for_tx_update_mk_tree(zeth_client, mk_tree, tx_hash)
except Exception as e:
print(
"Charlie's second corruption attempt" +
f" successfully rejected! (msg: {e})"
)
assert(result_corrupt2 is None), \
"Charlie managed to corrupt Bob's deposit the second time!"
# Case3: Charlie uses the correct mix data, but attempts to send the mix
# call from his own address (thereby receiving the output).
result_corrupt3 = None
try:
joinsplit_sig_bob = joinsplit_sign(
joinsplit_keypair,
bob_eth_address,
ciphertexts,
proof_json)
mix_params = contracts.MixParameters(
proof_json,
joinsplit_keypair.vk,
joinsplit_sig_bob,
ciphertexts)
tx_hash = zeth_client.mix(
mix_params,
charlie_eth_address,
None,
EtherValue(BOB_DEPOSIT_ETH),
4000000)
result_corrupt3 = \
wait_for_tx_update_mk_tree(zeth_client, mk_tree, tx_hash)
except Exception as e:
print(
"Charlie's third corruption attempt" +
f" successfully rejected! (msg: {e})"
)
assert(result_corrupt3 is None), \
"Charlie managed to corrupt Bob's deposit the third time!"
# ### ATTACK BLOCK
# Bob transaction is finally mined
joinsplit_sig_bob = joinsplit_sign(
joinsplit_keypair,
bob_eth_address,
ciphertexts,
proof_json)
mix_params = contracts.MixParameters(
proof_json,
joinsplit_keypair.vk,
joinsplit_sig_bob,
ciphertexts)
tx_hash = zeth_client.mix(
mix_params,
bob_eth_address,
None,
EtherValue(BOB_DEPOSIT_ETH))
return wait_for_tx_update_mk_tree(zeth_client, mk_tree, tx_hash)
def charlie_double_withdraw(
zeth_client: MixerClient,
mk_tree: MerkleTree,
input1: Tuple[int, ZethNote],
charlie_eth_address: str,
keystore: mock.KeyStore) -> contracts.MixResult:
"""
Charlie tries to carry out a double spending by modifying the value of the
nullifier of the previous payment
"""
print(
f" === Charlie attempts to withdraw {CHARLIE_WITHDRAW_ETH}ETH once " +
"more (double spend) one of his note on the Mixer ===")
charlie_apk = keystore["Charlie"].addr_pk.a_pk
charlie_ask = keystore["Charlie"].addr_sk.a_sk
tree_depth = mk_tree.depth
mk_path1 = compute_merkle_path(input1[0], mk_tree)
mk_root = mk_tree.get_root()
# Create the an additional dummy input for the MixerClient
input2 = get_dummy_input_and_address(charlie_apk)
dummy_mk_path = mock.get_dummy_merkle_path(tree_depth)
note1_value = to_zeth_units(EtherValue(CHARLIE_WITHDRAW_CHANGE_ETH))
v_out = EtherValue(CHARLIE_WITHDRAW_ETH)
# ### ATTACK BLOCK
# Add malicious nullifiers: we reuse old nullifiers to double spend by
# adding $r$ to them so that they have the same value as before in Z_r,
# and so the zksnark verification passes, but have different values in
# {0;1}^256 so that they appear different to the contract.
# See: https://github.com/clearmatics/zeth/issues/38
attack_primary_input3: int = 0
attack_primary_input4: int = 0
def compute_h_sig_attack_nf(
nf0: bytes,
nf1: bytes,
sign_vk: JoinsplitSigVerificationKey) -> bytes:
# We disassemble the nfs to get the formatting of the primary inputs
input_nullifier0 = nf0.hex()
input_nullifier1 = nf1.hex()
nf0_rev = "{0:0256b}".format(int(input_nullifier0, 16))
primary_input3_bits = nf0_rev[:FIELD_CAPACITY]
primary_input3_res_bits = nf0_rev[FIELD_CAPACITY:]
nf1_rev = "{0:0256b}".format(int(input_nullifier1, 16))
primary_input4_bits = nf1_rev[:FIELD_CAPACITY]
primary_input4_res_bits = nf1_rev[FIELD_CAPACITY:]
# We perform the attack, recoding the modified public input values
nonlocal attack_primary_input3
nonlocal attack_primary_input4
attack_primary_input3 = int(primary_input3_bits, 2) + ZETH_PRIME
attack_primary_input4 = int(primary_input4_bits, 2) + ZETH_PRIME
# We reassemble the nfs
attack_primary_input3_bits = "{0:0256b}".format(attack_primary_input3)
attack_nf0_bits = attack_primary_input3_bits[
len(attack_primary_input3_bits) - FIELD_CAPACITY:] +\
primary_input3_res_bits
attack_nf0 = "{0:064x}".format(int(attack_nf0_bits, 2))
attack_primary_input4_bits = "{0:0256b}".format(attack_primary_input4)
attack_nf1_bits = attack_primary_input4_bits[
len(attack_primary_input4_bits) - FIELD_CAPACITY:] +\
primary_input4_res_bits
attack_nf1 = "{0:064x}".format(int(attack_nf1_bits, 2))
return compute_h_sig(
bytes.fromhex(attack_nf0), bytes.fromhex(attack_nf1), sign_vk)
(output_note1, output_note2, proof_json, signing_keypair) = \
zeth_client.get_proof_joinsplit_2_by_2(
mk_root,
input1,
mk_path1,
input2,
dummy_mk_path,
charlie_ask, # sender
(charlie_apk, note1_value), # recipient1
(charlie_apk, 0), # recipient2
to_zeth_units(EtherValue(0)), # v_in
to_zeth_units(v_out), # v_out
compute_h_sig_attack_nf)
# Update the primary inputs to the modified nullifiers, since libsnark
# overwrites them with values in Z_p
assert attack_primary_input3 != 0
assert attack_primary_input4 != 0
print("proof_json => ", proof_json)
print("proof_json[inputs][3] => ", proof_json["inputs"][3])
print("proof_json[inputs][4] => ", proof_json["inputs"][4])
proof_json["inputs"][3] = hex(attack_primary_input3)
proof_json["inputs"][4] = hex(attack_primary_input4)
# ### ATTACK BLOCK
# construct pk object from bytes
pk_charlie = keystore["Charlie"].addr_pk.k_pk
# encrypt the coins
ciphertexts = encrypt_notes([
(output_note1, pk_charlie),
(output_note2, pk_charlie)])
# Compute the joinSplit signature
joinsplit_sig_charlie = joinsplit_sign(
signing_keypair,
charlie_eth_address,
ciphertexts,
proof_json)
mix_params = contracts.MixParameters(
proof_json,
signing_keypair.vk,
joinsplit_sig_charlie,
ciphertexts)
tx_hash = zeth_client.mix(
mix_params,
charlie_eth_address,
# Pay an arbitrary amount (1 wei here) that will be refunded since the
# `mix` function is payable
None,
EtherValue(1, 'wei'))
return wait_for_tx_update_mk_tree(zeth_client, mk_tree, tx_hash)
def main() -> None:
zksnark_name = zeth.core.utils.parse_zksnark_arg()
zksnark = zeth.core.zksnark.get_zksnark_provider(zksnark_name)
web3, eth = mock.open_test_web3()
# Zeth addresses
keystore = mock.init_test_keystore()
# Ethereum addresses
deployer_eth_address = eth.accounts[0]
bob_eth_address = eth.accounts[1]
alice_eth_address = eth.accounts[2]
charlie_eth_address = eth.accounts[3]
# ProverClient
prover_client = ProverClient(mock.TEST_PROVER_SERVER_ENDPOINT)
prover_config = prover_client.get_configuration()
pp = prover_config.pairing_parameters
assert prover_client.get_configuration().zksnark_name == zksnark_name
# Deploy Zeth contracts
tree_depth = zeth.core.constants.ZETH_MERKLE_TREE_DEPTH
zeth_client, _contract_desc = MixerClient.deploy(
web3,
prover_client,
deployer_eth_address,
None,
None,
None)
# Set up Merkle tree and Wallets. Note that each wallet holds an internal
# Merkle Tree, unused in this test. Instead, we keep an in-memory version
# shared by all virtual users. This avoids having to pass all mix results
# to all wallets, and allows some of the methods in the scenario module,
# which must update the tree directly.
tree_hash = get_tree_hash_for_pairing(pp.name)
mk_tree = zeth.core.merkle_tree.MerkleTree.empty_with_depth(
tree_depth, tree_hash)
mixer_instance = zeth_client.mixer_instance
# Keys and wallets
def _mk_wallet(name: str, sk: ZethAddressPriv) -> Wallet:
wallet_dir = join(mock.TEST_NOTE_DIR, name + "-eth")
if exists(wallet_dir):
# Note: symlink-attack resistance
# https://docs.python.org/3/library/shutil.html#shutil.rmtree.avoids_symlink_attacks
shutil.rmtree(wallet_dir)
return Wallet(mixer_instance, name, wallet_dir, sk, tree_hash)
sk_alice = keystore['Alice'].addr_sk
sk_bob = keystore['Bob'].addr_sk
sk_charlie = keystore['Charlie'].addr_sk
alice_wallet = _mk_wallet('alice', sk_alice)
bob_wallet = _mk_wallet('bob', sk_bob)
charlie_wallet = _mk_wallet('charlie', sk_charlie)
block_num = 1
# Universal update function
def _receive_notes(
out_ev: List[MixOutputEvents]) \
-> Dict[str, List[ZethNoteDescription]]:
nonlocal block_num
notes = {
'alice': alice_wallet.receive_notes(out_ev, pp),
'bob': bob_wallet.receive_notes(out_ev, pp),
'charlie': charlie_wallet.receive_notes(out_ev, pp),
}
alice_wallet.update_and_save_state(block_num)
bob_wallet.update_and_save_state(block_num)
charlie_wallet.update_and_save_state(block_num)
block_num = block_num + 1
return notes
print("[INFO] 4. Running tests (asset mixed: Ether)...")
print("- Initial balances: ")
print_balances(
web3,
bob_eth_address,
alice_eth_address,
charlie_eth_address,
zeth_client.mixer_instance.address)
# Bob deposits ETH, split in 2 notes on the mixer
result_deposit_bob_to_bob = scenario.bob_deposit(
zeth_client,
prover_client,
mk_tree,
bob_eth_address,
keystore)
print("- Balances after Bob's deposit: ")
print_balances(
web3,
bob_eth_address,
alice_eth_address,
charlie_eth_address,
zeth_client.mixer_instance.address
)
# Alice sees a deposit and tries to decrypt the ciphertexts to see if she
# was the recipient but she wasn't the recipient (Bob was), so she fails to
# decrypt
recovered_notes = _receive_notes(result_deposit_bob_to_bob.output_events)
assert(len(recovered_notes['alice']) == 0), \
"Alice decrypted a ciphertext that was not encrypted with her key!"
# Bob does a transfer to Charlie on the mixer
# Bob decrypts one of the note he previously received (useless here but
# useful if the payment came from someone else)
assert(len(recovered_notes['bob']) == 2), \
f"Bob recovered {len(recovered_notes['bob'])} notes, expected 2"
# Execution of the transfer
result_transfer_bob_to_charlie = scenario.bob_to_charlie(
zeth_client,
prover_client,
mk_tree,
recovered_notes['bob'][0].as_input(),
bob_eth_address,
keystore)
# Bob tries to spend `input_note_bob_to_charlie` twice
result_double_spending = None
try:
result_double_spending = scenario.bob_to_charlie(
zeth_client,
prover_client,
mk_tree,
recovered_notes['bob'][0].as_input(),
bob_eth_address,
keystore)
except Exception as e:
print(f"Bob's double spending successfully rejected! (msg: {e})")
assert(result_double_spending is None), \
"Bob managed to spend the same note twice!"
print("- Balances after Bob's transfer to Charlie: ")
print_balances(
web3,
bob_eth_address,
alice_eth_address,
charlie_eth_address,
zeth_client.mixer_instance.address
)
# Charlie recovers his notes and attempts to withdraw them.
recovered_notes = _receive_notes(
result_transfer_bob_to_charlie.output_events)
notes_charlie = recovered_notes['charlie']
assert(len(notes_charlie) == 1), \
f"Charlie decrypted {len(notes_charlie)}. Expected 1!"
input_charlie_withdraw = notes_charlie[0]
charlie_balance_before_withdrawal = eth.getBalance(charlie_eth_address)
_ = scenario.charlie_withdraw(
zeth_client,
prover_client,
mk_tree,
input_charlie_withdraw.as_input(),
charlie_eth_address,
keystore)
charlie_balance_after_withdrawal = eth.getBalance(charlie_eth_address)
print("Balances after Charlie's withdrawal: ")
print_balances(
web3,
bob_eth_address,
alice_eth_address,
charlie_eth_address,
zeth_client.mixer_instance.address)
if charlie_balance_after_withdrawal <= charlie_balance_before_withdrawal:
raise Exception("Charlie's balance did not increase after withdrawal")
# Charlie tries to double-spend by withdrawing twice the same note
result_double_spending = None
try:
# New commitments are added in the tree at each withdraw so we
# recompiute the path to have the updated nodes
result_double_spending = scenario.charlie_double_withdraw(
zeth_client,
prover_client,
zksnark,
mk_tree,
input_charlie_withdraw.as_input(),
charlie_eth_address,
keystore)
except Exception as e:
print(f"Charlie's double spending successfully rejected! (msg: {e})")
print("Balances after Charlie's double withdrawal attempt: ")
assert(result_double_spending is None), \
"Charlie managed to withdraw the same note twice!"
print_balances(
web3,
bob_eth_address,
alice_eth_address,
charlie_eth_address,
zeth_client.mixer_instance.address)
# Bob deposits once again ETH, split in 2 notes on the mixer
# But Charlie attempts to corrupt the transaction (malleability attack)
result_deposit_bob_to_bob = scenario.charlie_corrupt_bob_deposit(
zeth_client,
prover_client,
zksnark,
mk_tree,
bob_eth_address,
charlie_eth_address,
keystore)
# Bob decrypts one of the note he previously received (should fail if
# Charlie's attack succeeded)
recovered_notes = _receive_notes(
result_deposit_bob_to_bob.output_events)
assert(len(recovered_notes['bob']) == 2), \
f"Bob recovered {len(recovered_notes['bob'])} notes, expected 2"
print("- Balances after Bob's last deposit: ")
print_balances(
web3,
bob_eth_address,
alice_eth_address,
charlie_eth_address,
zeth_client.mixer_instance.address)
print(
"========================================\n" +
" TESTS PASSED\n" +
"========================================\n")
def charlie_double_withdraw(
zeth_client: MixerClient,
prover_client: ProverClient,
zksnark: IZKSnarkProvider,
mk_tree: MerkleTree,
input1: Tuple[int, ZethNote],
charlie_eth_address: str,
keystore: mock.KeyStore) -> MixResult:
"""
Charlie tries to carry out a double spending by modifying the value of the
nullifier of the previous payment
"""
pp = zeth_client.prover_config.pairing_parameters
scalar_field_mod = pp.scalar_field_mod()
scalar_field_capacity = pp.scalar_field_capacity
print(
f" === Charlie attempts to withdraw {CHARLIE_WITHDRAW_ETH}ETH once " +
"more (double spend) one of his note on the Mixer ===")
charlie_addr = keystore["Charlie"]
charlie_apk = charlie_addr.addr_pk.a_pk
# Create the an additional dummy input for the MixerClient
input2 = get_dummy_input_and_address(charlie_apk)
note1_value = EtherValue(CHARLIE_WITHDRAW_CHANGE_ETH)
v_out = EtherValue(CHARLIE_WITHDRAW_ETH)
# ### ATTACK BLOCK
# Add malicious nullifiers: we reuse old nullifiers to double spend by
# adding $r$ to them so that they have the same value as before in Z_r,
# and so the zksnark verification passes, but have different values in
# {0;1}^256 so that they appear different to the contract.
# See: https://github.com/clearmatics/zeth/issues/38
attack_primary_input3: int = 0
attack_primary_input4: int = 0
def compute_h_sig_attack_nf(
nfs: List[bytes],
sign_vk: JoinsplitSigVerificationKey) -> bytes:
# We disassemble the nfs to get the formatting of the primary inputs
assert len(nfs) == 2
nf0 = nfs[0]
nf1 = nfs[1]
input_nullifier0 = nf0.hex()
input_nullifier1 = nf1.hex()
nf0_rev = "{0:0256b}".format(int(input_nullifier0, 16))
primary_input3_bits = nf0_rev[:scalar_field_capacity]
primary_input3_res_bits = nf0_rev[scalar_field_capacity:]
nf1_rev = "{0:0256b}".format(int(input_nullifier1, 16))
primary_input4_bits = nf1_rev[:scalar_field_capacity]
primary_input4_res_bits = nf1_rev[scalar_field_capacity:]
# We perform the attack, recoding the modified public input values
nonlocal attack_primary_input3
nonlocal attack_primary_input4
attack_primary_input3 = int(primary_input3_bits, 2) + scalar_field_mod
attack_primary_input4 = int(primary_input4_bits, 2) + scalar_field_mod
# We reassemble the nfs
attack_primary_input3_bits = "{0:0256b}".format(attack_primary_input3)
attack_nf0_bits = attack_primary_input3_bits[
len(attack_primary_input3_bits) - scalar_field_capacity:] +\
primary_input3_res_bits
attack_nf0 = "{0:064x}".format(int(attack_nf0_bits, 2))
attack_primary_input4_bits = "{0:0256b}".format(attack_primary_input4)
attack_nf1_bits = attack_primary_input4_bits[
len(attack_primary_input4_bits) - scalar_field_capacity:] +\
primary_input4_res_bits
attack_nf1 = "{0:064x}".format(int(attack_nf1_bits, 2))
return compute_h_sig(
[bytes.fromhex(attack_nf0), bytes.fromhex(attack_nf1)], sign_vk)
output_note1, output_note2, proof, public_data, signing_keypair = \
get_mix_parameters_components(
zeth_client,
prover_client,
mk_tree,
keystore["Charlie"].ownership_keypair(), # sender
[input1, input2],
[(charlie_addr.addr_pk, note1_value),
(charlie_addr.addr_pk, EtherValue(0))],
EtherValue(0),
v_out,
compute_h_sig_attack_nf)
# Update the primary inputs to the modified nullifiers, since libsnark
# overwrites them with values in Z_p
assert attack_primary_input3 != 0
assert attack_primary_input4 != 0
print("proof = ", proof)
print("public_data[3] = ", public_data[3])
print("public_data[4] = ", public_data[4])
public_data[3] = attack_primary_input3
public_data[4] = attack_primary_input4
# ### ATTACK BLOCK
# construct pk object from bytes
pk_charlie = keystore["Charlie"].addr_pk.k_pk
# encrypt the coins
ciphertexts = encrypt_notes([
(output_note1, pk_charlie),
(output_note2, pk_charlie)])
# Compute the joinSplit signature
joinsplit_sig_charlie = joinsplit_sign(
zksnark,
pp,
signing_keypair,
charlie_eth_address,
ciphertexts,
proof,
public_data)
mix_params = MixParameters(
proof,
public_data,
signing_keypair.vk,
joinsplit_sig_charlie,
ciphertexts)
tx_hash = zeth_client.mix(
mix_params,
charlie_eth_address,
# Pay an arbitrary amount (1 wei here) that will be refunded since the
# `mix` function is payable
None,
EtherValue(1, 'wei'))
return wait_for_tx_update_mk_tree(zeth_client, mk_tree, tx_hash)
def main() -> None:
zksnark_name = zeth.core.utils.parse_zksnark_arg()
zksnark = zeth.core.zksnark.get_zksnark_provider(zksnark_name)
web3, eth = mock.open_test_web3()
# Ethereum addresses
deployer_eth_address = eth.accounts[0]
bob_eth_address = eth.accounts[1]
alice_eth_address = eth.accounts[2]
charlie_eth_address = eth.accounts[3]
# Zeth addresses
keystore = mock.init_test_keystore()
# Deploy the token contract
token_instance = deploy_token(web3, deployer_eth_address, None, 4000000)
# ProverClient
prover_client = ProverClient(mock.TEST_PROVER_SERVER_ENDPOINT)
prover_config = prover_client.get_configuration()
pp = prover_config.pairing_parameters
assert prover_client.get_configuration().zksnark_name == zksnark_name
# Deploy Zeth contracts
tree_depth = constants.ZETH_MERKLE_TREE_DEPTH
zeth_client, _contract_desc = MixerClient.deploy(web3, prover_client,
deployer_eth_address,
None,
token_instance.address,
None)
tree_hash = get_tree_hash_for_pairing(pp.name)
mk_tree = zeth.core.merkle_tree.MerkleTree.empty_with_depth(
tree_depth, tree_hash)
mixer_instance = zeth_client.mixer_instance
# Keys and wallets
def _mk_wallet(name: str, sk: ZethAddressPriv) -> Wallet:
wallet_dir = join(mock.TEST_NOTE_DIR, name + "-erc")
if exists(wallet_dir):
# Note: symlink-attack resistance
# https://docs.python.org/3/library/shutil.html#shutil.rmtree.avoids_symlink_attacks
shutil.rmtree(wallet_dir)
return Wallet(mixer_instance, name, wallet_dir, sk, tree_hash)
sk_alice = keystore["Alice"].addr_sk
sk_bob = keystore["Bob"].addr_sk
sk_charlie = keystore["Charlie"].addr_sk
alice_wallet = _mk_wallet('alice', sk_alice)
bob_wallet = _mk_wallet('bob', sk_bob)
charlie_wallet = _mk_wallet('charlie', sk_charlie)
block_num = 1
# Universal update function
def _receive_notes(
out_ev: List[MixOutputEvents]) \
-> Dict[str, List[ZethNoteDescription]]:
nonlocal block_num
notes = {
'alice': alice_wallet.receive_notes(out_ev, pp),
'bob': bob_wallet.receive_notes(out_ev, pp),
'charlie': charlie_wallet.receive_notes(out_ev, pp),
}
alice_wallet.update_and_save_state(block_num)
bob_wallet.update_and_save_state(block_num)
charlie_wallet.update_and_save_state(block_num)
block_num = block_num + 1
return notes
print("[INFO] 4. Running tests (asset mixed: ERC20 token)...")
# We assign ETHToken to Bob
mint_token(web3, token_instance, bob_eth_address, deployer_eth_address,
None, EtherValue(2 * scenario.BOB_DEPOSIT_ETH, 'ether'))
print("- Initial balances: ")
print_token_balances(token_instance, bob_eth_address, alice_eth_address,
charlie_eth_address,
zeth_client.mixer_instance.address)
# Bob tries to deposit ETHToken, split in 2 notes on the mixer (without
# approving)
try:
result_deposit_bob_to_bob = scenario.bob_deposit(
zeth_client, prover_client, mk_tree, bob_eth_address, keystore,
zeth.core.utils.EtherValue(0))
except Exception as e:
allowance_mixer = allowance(token_instance, bob_eth_address,
zeth_client.mixer_instance.address)
print(f"[ERROR] Bob deposit failed! (msg: {e})")
print("The allowance for Mixer from Bob is: ", allowance_mixer)
# Bob approves the transfer
print("- Bob approves the transfer of ETHToken to the Mixer")
tx_hash = approve(token_instance, bob_eth_address,
zeth_client.mixer_instance.address,
scenario.BOB_DEPOSIT_ETH)
eth.waitForTransactionReceipt(tx_hash)
allowance_mixer = allowance(token_instance, bob_eth_address,
zeth_client.mixer_instance.address)
print("- The allowance for the Mixer from Bob is:", allowance_mixer)
# Bob deposits ETHToken, split in 2 notes on the mixer
result_deposit_bob_to_bob = scenario.bob_deposit(zeth_client,
prover_client, mk_tree,
bob_eth_address, keystore)
print("- Balances after Bob's deposit: ")
print_token_balances(token_instance, bob_eth_address, alice_eth_address,
charlie_eth_address,
zeth_client.mixer_instance.address)
# Alice sees a deposit and tries to decrypt the ciphertexts to see if she
# was the recipient, but Bob was the recipient so Alice fails to decrypt
received_notes = _receive_notes(result_deposit_bob_to_bob.output_events)
recovered_notes_alice = received_notes['alice']
assert(len(recovered_notes_alice) == 0), \
"Alice decrypted a ciphertext that was not encrypted with her key!"
# Bob does a transfer of ETHToken to Charlie on the mixer
# Bob decrypts one of the note he previously received (useless here but
# useful if the payment came from someone else)
recovered_notes_bob = received_notes['bob']
assert(len(recovered_notes_bob) == 2), \
f"Bob recovered {len(recovered_notes_bob)} notes from deposit, expected 2"
input_bob_to_charlie = recovered_notes_bob[0].as_input()
# Execution of the transfer
result_transfer_bob_to_charlie = scenario.bob_to_charlie(
zeth_client, prover_client, mk_tree, input_bob_to_charlie,
bob_eth_address, keystore)
# Bob tries to spend `input_note_bob_to_charlie` twice
result_double_spending = None
try:
result_double_spending = scenario.bob_to_charlie(
zeth_client, prover_client, mk_tree, input_bob_to_charlie,
bob_eth_address, keystore)
except Exception as e:
print(f"Bob's double spending successfully rejected! (msg: {e})")
assert (result_double_spending is None), "Bob spent the same note twice!"
print("- Balances after Bob's transfer to Charlie: ")
print_token_balances(token_instance, bob_eth_address, alice_eth_address,
charlie_eth_address,
zeth_client.mixer_instance.address)
# Charlie tries to decrypt the notes from Bob's previous transaction.
received_notes = _receive_notes(
result_transfer_bob_to_charlie.output_events)
note_descs_charlie = received_notes['charlie']
assert(len(note_descs_charlie) == 1), \
f"Charlie decrypted {len(note_descs_charlie)}. Expected 1!"
_ = scenario.charlie_withdraw(zeth_client, prover_client, mk_tree,
note_descs_charlie[0].as_input(),
charlie_eth_address, keystore)
print("- Balances after Charlie's withdrawal: ")
print_token_balances(token_instance, bob_eth_address, alice_eth_address,
charlie_eth_address,
zeth_client.mixer_instance.address)
# Charlie tries to carry out a double spend by withdrawing twice the same
# note
result_double_spending = None
try:
# New commitments are added in the tree at each withdraw so we
# recompute the path to have the updated nodes
result_double_spending = scenario.charlie_double_withdraw(
zeth_client, prover_client, zksnark, mk_tree,
note_descs_charlie[0].as_input(), charlie_eth_address, keystore)
except Exception as e:
print(f"Charlie's double spending successfully rejected! (msg: {e})")
print("Balances after Charlie's double withdrawal attempt: ")
assert(result_double_spending is None), \
"Charlie managed to withdraw the same note twice!"
print_token_balances(token_instance, bob_eth_address, alice_eth_address,
charlie_eth_address,
zeth_client.mixer_instance.address)
# Bob deposits once again ETH, split in 2 notes on the mixer
# But Charlie attempts to corrupt the transaction (malleability attack)
# Bob approves the transfer
print("- Bob approves the transfer of ETHToken to the Mixer")
tx_hash = approve(token_instance, bob_eth_address,
zeth_client.mixer_instance.address,
scenario.BOB_DEPOSIT_ETH)
eth.waitForTransactionReceipt(tx_hash)
allowance_mixer = allowance(token_instance, bob_eth_address,
zeth_client.mixer_instance.address)
print("- The allowance for the Mixer from Bob is:", allowance_mixer)
result_deposit_bob_to_bob = scenario.charlie_corrupt_bob_deposit(
zeth_client, prover_client, zksnark, mk_tree, bob_eth_address,
charlie_eth_address, keystore)
# Bob decrypts one of the note he previously received (should fail if
# Charlie's attack succeeded)
received_notes = _receive_notes(result_deposit_bob_to_bob.output_events)
recovered_notes_bob = received_notes['bob']
assert(len(recovered_notes_bob) == 2), \
f"Bob recovered {len(recovered_notes_bob)} notes from deposit, expected 2"
print("- Balances after Bob's last deposit: ")
print_token_balances(token_instance, bob_eth_address, alice_eth_address,
charlie_eth_address,
zeth_client.mixer_instance.address)
print("========================================\n" +
" TESTS PASSED\n" +
"========================================\n")
