def test_verify_challenge_tx_sequence_not_zero(self):
server_kp = Keypair.random()
client_kp = Keypair.random()
network_passphrase = Network.PUBLIC_NETWORK_PASSPHRASE
anchor_name = "SDF"
now = int(time.time())
nonce = os.urandom(48)
nonce_encoded = base64.b64encode(nonce)
server_account = Account(server_kp.public_key, 10086)
challenge_te = (TransactionBuilder(
server_account, network_passphrase, 100).append_manage_data_op(
data_name="{} auth".format(anchor_name),
data_value=nonce_encoded,
source=client_kp.public_key,
).add_time_bounds(now, now + 900).build())
challenge_te.sign(server_kp)
challenge_te.sign(client_kp)
challenge_tx_signed = challenge_te.to_xdr()
with pytest.raises(
InvalidSep10ChallengeError,
match="The transaction sequence number should be zero.",
):
verify_challenge_transaction(challenge_tx_signed,
server_kp.public_key,
network_passphrase)
def test_verify_challenge_tx_not_within_range_of_the_specified_timebounds(
self):
server_kp = Keypair.random()
client_kp = Keypair.random()
network_passphrase = Network.PUBLIC_NETWORK_PASSPHRASE
anchor_name = "SDF"
now = int(time.time())
nonce = os.urandom(48)
nonce_encoded = base64.b64encode(nonce)
server_account = Account(server_kp.public_key, -1)
challenge_te = (TransactionBuilder(
server_account, network_passphrase, 100).append_manage_data_op(
data_name="{} auth".format(anchor_name),
data_value=nonce_encoded,
source=client_kp.public_key,
).add_time_bounds(now - 100, now - 50).build())
challenge_te.sign(server_kp)
challenge_te.sign(client_kp)
challenge_tx_signed = challenge_te.to_xdr()
with pytest.raises(
InvalidSep10ChallengeError,
match=
"Transaction is not within range of the specified timebounds.",
):
verify_challenge_transaction(challenge_tx_signed,
server_kp.public_key,
network_passphrase)
def test_verify_challenge_tx_transaction_is_not_signed_by_the_server(self):
server_kp = Keypair.random()
client_kp = Keypair.random()
network_passphrase = Network.PUBLIC_NETWORK_PASSPHRASE
anchor_name = "SDF"
timeout = 900
now = int(time.time())
server_keypair = Keypair.from_secret(server_kp.secret)
server_account = Account(account_id=server_keypair.public_key,
sequence=-1)
transaction_builder = TransactionBuilder(server_account,
network_passphrase, 100)
transaction_builder.add_time_bounds(min_time=now,
max_time=now + timeout)
nonce = os.urandom(48)
nonce_encoded = base64.b64encode(nonce)
transaction_builder.append_manage_data_op(
data_name="{} auth".format(anchor_name),
data_value=nonce_encoded,
source=client_kp.public_key,
)
challenge = transaction_builder.build().to_xdr()
transaction = TransactionEnvelope.from_xdr(challenge,
network_passphrase)
transaction.sign(client_kp)
challenge_tx = transaction.to_xdr()
with pytest.raises(
InvalidSep10ChallengeError,
match="Transaction not signed by server: {}".format(
server_kp.public_key),
):
verify_challenge_transaction(challenge_tx, server_kp.public_key,
network_passphrase)
def test_set_timeout(self):
source = Account("GDF5O4OWEMVBY5FLDHWA5RZTYSV2U276XGKZZ6VSHDDR3THSQ6OQS7UM", 1)
timeout = 1000
builder = TransactionBuilder(
source, Network.TESTNET_NETWORK_PASSPHRASE, base_fee=150
).set_timeout(1000)
now = int(time.time())
assert isinstance(builder.time_bounds, TimeBounds)
assert builder.time_bounds.min_time == 0
assert now + timeout - 1 <= builder.time_bounds.max_time <= now + timeout + 1
def test_set_timeout_timebounds_raise(self):
source = Account("GDF5O4OWEMVBY5FLDHWA5RZTYSV2U276XGKZZ6VSHDDR3THSQ6OQS7UM", 1)
timeout = 1000
now = int(time.time())
with pytest.raises(
ValueError,
match="TimeBounds has been already set - setting timeout would overwrite it.",
):
TransactionBuilder(
source, Network.TESTNET_NETWORK_PASSPHRASE, base_fee=150
).add_time_bounds(0, now + timeout).set_timeout(1000)
def test_add_memo(self):
source = Account("GDF5O4OWEMVBY5FLDHWA5RZTYSV2U276XGKZZ6VSHDDR3THSQ6OQS7UM", 1)
builder = TransactionBuilder(
source, Network.TESTNET_NETWORK_PASSPHRASE, base_fee=150
).add_id_memo(100)
assert builder.memo == IdMemo(100)
memo_hash = os.urandom(32)
builder = TransactionBuilder(
source, Network.TESTNET_NETWORK_PASSPHRASE, base_fee=150
).add_hash_memo(memo_hash)
assert builder.memo == HashMemo(memo_hash)
builder = TransactionBuilder(
source, Network.TESTNET_NETWORK_PASSPHRASE, base_fee=150
).add_return_hash_memo(memo_hash)
assert builder.memo == ReturnHashMemo(memo_hash)
def test_verify_transaction_signatures_raise_no_signature(self):
server_kp = Keypair.random()
client_kp = Keypair.random()
network_passphrase = Network.PUBLIC_NETWORK_PASSPHRASE
anchor_name = "SDF"
now = int(time.time())
nonce = os.urandom(48)
nonce_encoded = base64.b64encode(nonce)
server_account = Account(server_kp.public_key, -1)
challenge_te = (TransactionBuilder(
server_account, network_passphrase, 100).append_manage_data_op(
data_name="{} auth".format(anchor_name),
data_value=nonce_encoded,
source=client_kp.public_key,
).add_time_bounds(now, now + 900).build())
signers = []
with pytest.raises(InvalidSep10ChallengeError,
match="Transaction has no signatures."):
_verify_transaction_signatures(challenge_te, signers)
def test_verify_challenge_tx_donot_contain_managedata_operation(self):
server_kp = Keypair.random()
client_kp = Keypair.random()
network_passphrase = Network.PUBLIC_NETWORK_PASSPHRASE
now = int(time.time())
server_account = Account(server_kp.public_key, -1)
challenge_te = (TransactionBuilder(
server_account, network_passphrase,
100).append_set_options_op().add_time_bounds(now,
now + 900).build())
challenge_te.sign(server_kp)
challenge_te.sign(client_kp)
challenge_tx_signed = challenge_te.to_xdr()
with pytest.raises(InvalidSep10ChallengeError,
match="Operation type should be ManageData."):
verify_challenge_transaction(challenge_tx_signed,
server_kp.public_key,
network_passphrase)
def test_verify_challenge_tx_dont_contains_timebound(self):
server_kp = Keypair.random()
client_kp = Keypair.random()
network_passphrase = Network.PUBLIC_NETWORK_PASSPHRASE
anchor_name = "SDF"
nonce = os.urandom(48)
nonce_encoded = base64.b64encode(nonce)
server_account = Account(server_kp.public_key, -1)
challenge_te = (TransactionBuilder(
server_account, network_passphrase, 100).append_manage_data_op(
data_name="{} auth".format(anchor_name),
data_value=nonce_encoded,
source=client_kp.public_key,
).build())
challenge_te.sign(server_kp)
challenge_te.sign(client_kp)
challenge_tx_signed = challenge_te.to_xdr()
with pytest.raises(InvalidSep10ChallengeError,
match="Transaction requires timebounds."):
verify_challenge_transaction(challenge_tx_signed,
server_kp.public_key,
network_passphrase)
def test_to_xdr(self):
sequence = 1
source = Account(
"GDF5O4OWEMVBY5FLDHWA5RZTYSV2U276XGKZZ6VSHDDR3THSQ6OQS7UM", sequence
)
builder = TransactionBuilder(
source, Network.TESTNET_NETWORK_PASSPHRASE, base_fee=150
)
builder.add_text_memo("Paydex Python SDK")
builder.add_time_bounds(1565590000, 1565600000)
te = (
builder.append_create_account_op(
"GDNSSYSCSSJ76FER5WEEXME5G4MTCUBKDRQSKOYP36KUKVDB2VCMERS6",
"5.5",
"GDF5O4OWEMVBY5FLDHWA5RZTYSV2U276XGKZZ6VSHDDR3THSQ6OQS7UM",
)
.append_change_trust_op(
"XCN",
"GDF5O4OWEMVBY5FLDHWA5RZTYSV2U276XGKZZ6VSHDDR3THSQ6OQS7UM",
"100000",
)
.append_payment_op(
"GAXN7HZQTHIPW7N2HGPAXMR42LPJ5VLYXMCCOX4D3JC4CQZGID3UYUPF",
"12.25",
"PAYDEX",
)
.append_path_payment_op(
"GAXN7HZQTHIPW7N2HGPAXMR42LPJ5VLYXMCCOX4D3JC4CQZGID3UYUPF",
"PAYDEX",
None,
"100",
"XCN",
"GDF5O4OWEMVBY5FLDHWA5RZTYSV2U276XGKZZ6VSHDDR3THSQ6OQS7UM",
"1000.5",
[
Asset(
"USD",
"GDNSSYSCSSJ76FER5WEEXME5G4MTCUBKDRQSKOYP36KUKVDB2VCMERS6",
),
Asset(
"BTC",
"GDNSSYSCSSJ76FER5WEEXME5G4MTCUBKDRQSKOYP36KUKVDB2VCMERS6",
),
],
)
.append_path_payment_strict_receive_op(
"GAXN7HZQTHIPW7N2HGPAXMR42LPJ5VLYXMCCOX4D3JC4CQZGID3UYUPF",
"PAYDEX",
None,
"100",
"XCN",
"GDF5O4OWEMVBY5FLDHWA5RZTYSV2U276XGKZZ6VSHDDR3THSQ6OQS7UM",
"1000.5",
[
Asset(
"USD",
"GDNSSYSCSSJ76FER5WEEXME5G4MTCUBKDRQSKOYP36KUKVDB2VCMERS6",
),
Asset(
"BTC",
"GDNSSYSCSSJ76FER5WEEXME5G4MTCUBKDRQSKOYP36KUKVDB2VCMERS6",
),
],
)
.append_path_payment_strict_send_op(
"GAXN7HZQTHIPW7N2HGPAXMR42LPJ5VLYXMCCOX4D3JC4CQZGID3UYUPF",
"PAYDEX",
None,
"100",
"XCN",
"GDF5O4OWEMVBY5FLDHWA5RZTYSV2U276XGKZZ6VSHDDR3THSQ6OQS7UM",
"1000.5",
[
Asset(
"USD",
"GDNSSYSCSSJ76FER5WEEXME5G4MTCUBKDRQSKOYP36KUKVDB2VCMERS6",
),
Asset(
"BTC",
"GDNSSYSCSSJ76FER5WEEXME5G4MTCUBKDRQSKOYP36KUKVDB2VCMERS6",
),
],
)
.append_allow_trust_op(
"GDNSSYSCSSJ76FER5WEEXME5G4MTCUBKDRQSKOYP36KUKVDB2VCMERS6", "XCN", True
)
.append_set_options_op(
"GAXN7HZQTHIPW7N2HGPAXMR42LPJ5VLYXMCCOX4D3JC4CQZGID3UYUPF",
1,
6,
20,
20,
20,
20,
"paydexcn.org",
Signer.ed25519_public_key(
"GAXN7HZQTHIPW7N2HGPAXMR42LPJ5VLYXMCCOX4D3JC4CQZGID3UYUPF", 10
),
"GDF5O4OWEMVBY5FLDHWA5RZTYSV2U276XGKZZ6VSHDDR3THSQ6OQS7UM",
)
.append_ed25519_public_key_signer(
"GCN4HBZGFPOAI5DF4YQIS6OBC6KJKDC7CJSS5B4FWEXMJSWOPEYABLSD", 5
)
.append_hashx_signer(
bytes.fromhex(
"3389e9f0f1a65f19736cacf544c2e825313e8447f569233bb8db39aa607c8000"
),
10,
)
.append_pre_auth_tx_signer(
bytes.fromhex(
"2db4b22ca018119c5027a80578813ffcf582cda4aa9e31cd92b43cfa4fc5a000"
),
10,
)
.append_inflation_op()
.append_manage_data_op("hello", "overcat")
.append_bump_sequence_op(10)
.append_manage_buy_offer_op(
"XCN",
"GCN4HBZGFPOAI5DF4YQIS6OBC6KJKDC7CJSS5B4FWEXMJSWOPEYABLSD",
"PAYDEX",
None,
"10.5",
"11.25",
)
.append_manage_sell_offer_op(
"PAYDEX",
None,
"XCN",
"GCN4HBZGFPOAI5DF4YQIS6OBC6KJKDC7CJSS5B4FWEXMJSWOPEYABLSD",
"10.5",
Price(8, 9),
10086,
)
.append_create_passive_sell_offer_op(
"XCN",
"GCN4HBZGFPOAI5DF4YQIS6OBC6KJKDC7CJSS5B4FWEXMJSWOPEYABLSD",
"PAYDEX",
None,
"10.5",
"11.25",
)
.append_account_merge_op(
"GAXN7HZQTHIPW7N2HGPAXMR42LPJ5VLYXMCCOX4D3JC4CQZGID3UYUPF"
)
.build()
)
xdr = "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"
assert te.to_xdr() == xdr
xdr_signed = "AAAAAMvXcdYjKhx0qxnsDsczxKuqa/65lZz6sjjHHczyh50JAAAKjAAAAAAAAAACAAAAAQAAAABdUQHwAAAAAF1RKQAAAAABAAAAElN0ZWxsYXIgUHl0aG9uIFNESwAAAAAAEgAAAAEAAAAAy9dx1iMqHHSrGewOxzPEq6pr/rmVnPqyOMcdzPKHnQkAAAAAAAAAANspYkKUk/8Uke2IS7CdNxkxUCocYSU7D9+VRVRh1UTCAAAAAANHO8AAAAAAAAAABgAAAAFYQ04AAAAAAMvXcdYjKhx0qxnsDsczxKuqa/65lZz6sjjHHczyh50JAAAA6NSlEAAAAAAAAAAAAQAAAAAu358wmdD7fbo5nguyPNLentV4uwQnX4PaRcFDJkD3TAAAAAAAAAAAB00zoAAAAAAAAAACAAAAAAAAAAA7msoAAAAAAC7fnzCZ0Pt9ujmeC7I80t6e1Xi7BCdfg9pFwUMmQPdMAAAAAVhDTgAAAAAAy9dx1iMqHHSrGewOxzPEq6pr/rmVnPqyOMcdzPKHnQkAAAACVFgvQAAAAAIAAAABVVNEAAAAAADbKWJClJP/FJHtiEuwnTcZMVAqHGElOw/flUVUYdVEwgAAAAFCVEMAAAAAANspYkKUk/8Uke2IS7CdNxkxUCocYSU7D9+VRVRh1UTCAAAAAAAAAAIAAAAAAAAAADuaygAAAAAALt+fMJnQ+326OZ4LsjzS3p7VeLsEJ1+D2kXBQyZA90wAAAABWENOAAAAAADL13HWIyocdKsZ7A7HM8Srqmv+uZWc+rI4xx3M8oedCQAAAAJUWC9AAAAAAgAAAAFVU0QAAAAAANspYkKUk/8Uke2IS7CdNxkxUCocYSU7D9+VRVRh1UTCAAAAAUJUQwAAAAAA2yliQpST/xSR7YhLsJ03GTFQKhxhJTsP35VFVGHVRMIAAAAAAAAADQAAAAAAAAAAO5rKAAAAAAAu358wmdD7fbo5nguyPNLentV4uwQnX4PaRcFDJkD3TAAAAAFYQ04AAAAAAMvXcdYjKhx0qxnsDsczxKuqa/65lZz6sjjHHczyh50JAAAAAlRYL0AAAAACAAAAAVVTRAAAAAAA2yliQpST/xSR7YhLsJ03GTFQKhxhJTsP35VFVGHVRMIAAAABQlRDAAAAAADbKWJClJP/FJHtiEuwnTcZMVAqHGElOw/flUVUYdVEwgAAAAAAAAAHAAAAANspYkKUk/8Uke2IS7CdNxkxUCocYSU7D9+VRVRh1UTCAAAAAVhDTgAAAAABAAAAAQAAAADL13HWIyocdKsZ7A7HM8Srqmv+uZWc+rI4xx3M8oedCQAAAAUAAAABAAAAAC7fnzCZ0Pt9ujmeC7I80t6e1Xi7BCdfg9pFwUMmQPdMAAAAAQAAAAEAAAABAAAABgAAAAEAAAAUAAAAAQAAABQAAAABAAAAFAAAAAEAAAAUAAAAAQAAAA1zdGVsbGFyY24ub3JnAAAAAAAAAQAAAAAu358wmdD7fbo5nguyPNLentV4uwQnX4PaRcFDJkD3TAAAAAoAAAAAAAAABQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAQAAAACbw4cmK9wEdGXmIIl5wReUlQxfEmUuh4WxLsTKznkwAAAAAAUAAAAAAAAABQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAQAAAAIzienw8aZfGXNsrPVEwuglMT6ER/VpIzu42zmqYHyAAAAAAAoAAAAAAAAABQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAQAAAAEttLIsoBgRnFAnqAV4gT/89YLNpKqeMc2StDz6T8WgAAAAAAoAAAAAAAAACQAAAAAAAAAKAAAABWhlbGxvAAAAAAAAAQAAAAdvdmVyY2F0AAAAAAAAAAALAAAAAAAAAAoAAAAAAAAADAAAAAFYQ04AAAAAAJvDhyYr3AR0ZeYgiXnBF5SVDF8SZS6HhbEuxMrOeTAAAAAAAAAAAAAGQixAAAAALQAAAAQAAAAAAAAAAAAAAAAAAAADAAAAAAAAAAFYQ04AAAAAAJvDhyYr3AR0ZeYgiXnBF5SVDF8SZS6HhbEuxMrOeTAAAAAAAAZCLEAAAAAIAAAACQAAAAAAACdmAAAAAAAAAAQAAAABWENOAAAAAACbw4cmK9wEdGXmIIl5wReUlQxfEmUuh4WxLsTKznkwAAAAAAAAAAAABkIsQAAAAC0AAAAEAAAAAAAAAAgAAAAALt+fMJnQ+326OZ4LsjzS3p7VeLsEJ1+D2kXBQyZA90wAAAAAAAAAAfKHnQkAAABAK4QrN2s/qldwTQG+XHZ/KgKmc1t3MoTE7wa34OuIBVCDdC58WChaHVaB40hcGGbR6Q9Y83Qdj+e1dPNLBQ18Bw=="
signer = Keypair.from_secret(
"SCCS5ZBI7WVIJ4SW36WGOQQIWJYCL3VOAULSXX3FB57USIO25EDOYQHH"
)
te.sign(signer)
assert te.to_xdr() == xdr_signed
restore_te = TransactionBuilder.from_xdr(
xdr_signed, Network.TESTNET_NETWORK_PASSPHRASE
).build()
assert restore_te.to_xdr() == xdr
assert source.sequence == sequence + 1