label = policy_data["label"].encode()
treasure_map = EncryptedTreasureMap.from_bytes(
base64.b64decode(policy_data["treasure_map"].encode()))
# The Doctor can retrieve encrypted data which he can decrypt with his private key.
# But first we need some encrypted data!
# Let's read the file produced by the heart monitor and unpack the MessageKits,
# which are the individual ciphertexts.
data = msgpack.load(open("heart_data.msgpack", "rb"), raw=False)
message_kits = (MessageKit.from_bytes(k) for k in data['kits'])
# Now he can ask the NuCypher network to get a re-encrypted version of each MessageKit.
for message_kit in message_kits:
start = timer()
retrieved_plaintexts = doctor.retrieve_and_decrypt(
[message_kit],
alice_verifying_key=alices_sig_pubkey,
encrypted_treasure_map=treasure_map)
end = timer()
plaintext = msgpack.loads(retrieved_plaintexts[0], raw=False)
# Now we can get the heart rate and the associated timestamp,
# generated by the heart rate monitor.
heart_rate = plaintext['heart_rate']
timestamp = maya.MayaDT(plaintext['timestamp'])
# This code block simply pretty prints the heart rate info
terminal_size = shutil.get_terminal_size().columns
max_width = min(terminal_size, 120)
columns = max_width - 12 - 27
scale = columns / 40
for counter, plaintext in enumerate(finnegans_wake):
# Enrico knows the policy's public key from a side-channel.
# In this demo a new enrico is being constructed for each line of text.
# This demonstrates how many individual encryptors may encrypt for a single policy.
# In other words -- Many data sources (Enricos) can encrypt for the policy's public key.
enrico = Enrico(policy_encrypting_key=policy_public_key)
# In this case, the plaintext is a single passage from James Joyce's Finnegan's Wake.
# The matter of whether encryption makes the passage more or less readable
# is left to the reader to determine.
message_kit = enrico.encrypt_message(plaintext)
enrico_public_key = bytes(enrico.stamp)
del enrico
###############
# Back to Bob #
###############
# Now Bob can retrieve the original message by requesting re-encryption from nodes.
cleartexts = bob.retrieve_and_decrypt(
[message_kit],
alice_verifying_key=alice_verifying_key,
encrypted_treasure_map=policy.treasure_map)
# We show that indeed this is the passage originally encrypted by Enrico.
assert plaintext == cleartexts[0]
print(cleartexts)
bob.disenchant()
def test_bob_retrieves(federated_alice, federated_ursulas,
certificates_tempdir):
# Let's partition Ursulas in two parts
a_couple_of_ursulas = list(federated_ursulas)[:2]
rest_of_ursulas = list(federated_ursulas)[2:]
# Bob becomes
bob = Bob(
federated_only=True,
domain=TEMPORARY_DOMAIN,
start_learning_now=True,
network_middleware=MockRestMiddleware(),
abort_on_learning_error=True,
known_nodes=a_couple_of_ursulas,
)
# Bob has only connected to - at most - 2 nodes.
assert sum(node.verified_node for node in bob.known_nodes) <= 2
# Alice creates a policy granting access to Bob
# Just for fun, let's assume she distributes KFrags among Ursulas unknown to Bob
shares = NUMBER_OF_URSULAS_IN_DEVELOPMENT_NETWORK - 2
label = b'label://' + os.urandom(32)
contract_end_datetime = maya.now() + datetime.timedelta(days=5)
policy = federated_alice.grant(
bob=bob,
label=label,
threshold=3,
shares=shares,
expiration=contract_end_datetime,
ursulas=set(rest_of_ursulas),
)
assert label == policy.label
# Enrico becomes
enrico = Enrico(policy_encrypting_key=policy.public_key)
plaintext = b"What's your approach? Mississippis or what?"
message_kit = enrico.encrypt_message(plaintext)
alices_verifying_key = federated_alice.stamp.as_umbral_pubkey()
# Bob takes the message_kit and retrieves the message within
delivered_cleartexts = bob.retrieve_and_decrypt(
[message_kit],
alice_verifying_key=alices_verifying_key,
encrypted_treasure_map=policy.treasure_map)
assert plaintext == delivered_cleartexts[0]
cleartexts_delivered_a_second_time = bob.retrieve_and_decrypt(
[message_kit],
alice_verifying_key=alices_verifying_key,
encrypted_treasure_map=policy.treasure_map)
# Indeed, they're the same cleartexts.
assert delivered_cleartexts == cleartexts_delivered_a_second_time
# Let's try retrieve again, but Alice revoked the policy.
receipt, failed_revocations = federated_alice.revoke(policy)
assert len(failed_revocations) == 0
# One thing to note here is that Bob *can* still retrieve with the cached CFrags,
# even though this Policy has been revoked. #892
_cleartexts = bob.retrieve_and_decrypt(
[message_kit],
alice_verifying_key=alices_verifying_key,
encrypted_treasure_map=policy.treasure_map)
assert _cleartexts == delivered_cleartexts # TODO: 892
bob.disenchant()
