main.py

import datetime
import os
import shutil

import maya
from twisted.logger import globalLogPublisher

from nucypher.characters.lawful import Alice, Bob, Ursula
from nucypher.data_sources import DataSource as Enrico
from nucypher.network.middleware import RestMiddleware
from nucypher.utilities.logging import simpleObserver
from umbral.keys import UmbralPublicKey
from nucypher.crypto.powers import SigningPower

######################
# Boring setup stuff #
######################

# Execute the download script (download_finnegans_wake.sh) to retrieve the book
BOOK_PATH = os.path.join('.', 'finnegans-wake.txt')

# Twisted Logger
globalLogPublisher.addObserver(simpleObserver)

# Temporary file storage
TEMP_FILES_DIR = "{}/examples-runtime-cruft".format(os.path.dirname(os.path.abspath(__file__)))
TEMP_DEMO_DIR = "{}/finnegans-wake-demo".format(TEMP_FILES_DIR)
TEMP_CERTIFICATE_DIR = "{}/certs".format(TEMP_DEMO_DIR)

# Remove previous demo files and create new ones
shutil.rmtree(TEMP_FILES_DIR, ignore_errors=True)
os.mkdir(TEMP_FILES_DIR)
os.mkdir(TEMP_DEMO_DIR)
os.mkdir(TEMP_CERTIFICATE_DIR)

#######################################
# Finnegan's Wake on NuCypher Testnet #
# (will fail with bad connection) #####
#######################################

TESTNET_LOAD_BALANCER = "eu-federated-balancer-40be4480ec380cd7.elb.eu-central-1.amazonaws.com"

##############################################
# Ursula, the Untrusted Re-Encryption Proxy  #
##############################################
ursula = Ursula.from_seed_and_stake_info(host=TESTNET_LOAD_BALANCER,
                                         certificates_directory=TEMP_CERTIFICATE_DIR,
                                         federated_only=True,
                                         minimum_stake=0)

# Here are our Policy details.
policy_end_datetime = maya.now() + datetime.timedelta(days=5)
m, n = 2, 3
label = b"secret/files/and/stuff"

######################################
# Alice, the Authority of the Policy #
######################################

ALICE = Alice(network_middleware=RestMiddleware(),
              known_nodes=[ursula],
              learn_on_same_thread=True,
              federated_only=True,
              known_certificates_dir=TEMP_CERTIFICATE_DIR)

BOB = Bob(
    known_nodes=[ursula],
    network_middleware=RestMiddleware(),
    federated_only=True,
    start_learning_now=True,
    learn_on_same_thread=True,
    known_certificates_dir=TEMP_CERTIFICATE_DIR)

ALICE.start_learning_loop(now=True)

policy = ALICE.grant(BOB,
                     label,
                     m=m, n=n,
                     expiration=policy_end_datetime)

# Alice puts her public key somewhere for Bob to find later...
alices_pubkey_bytes_saved_for_posterity = bytes(ALICE.stamp)

# ...and then disappears from the internet.
# del ALICE

#####################
# some time passes. #
# ...               #
#                   #
# ...               #
# And now for Bob.  #
#####################

#####################
# Bob the BUIDLer  ##
#####################

BOB.join_policy(label, alices_pubkey_bytes_saved_for_posterity)

# Now that Bob has joined the Policy, let's show how Enrico the Encryptor
# can share data with the members of this Policy and then how Bob retrieves it.
with open(BOOK_PATH, 'rb') as file:
    finnegans_wake = file.readlines()

print()
print("**************James Joyce's Finnegan's Wake**************")
print()
print("---------------------------------------------------------")

for counter, plaintext in enumerate(finnegans_wake):
    #########################
    # Enrico, the Encryptor #
    #########################
    enciro = Enrico(policy_pubkey_enc=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.
    single_passage_ciphertext, _signature = enciro.encapsulate_single_message(plaintext)
    data_source_public_key = bytes(enciro.stamp)
    del enciro

    ###############
    # Back to Bob #
    ###############

    enrico_as_understood_by_bob = Enrico.from_public_keys(
        policy_public_key=policy.public_key,
        datasource_public_key=data_source_public_key,
        label=label
    )

    # Now Bob can retrieve the original message.
    alice_pubkey_restored_from_ancient_scroll = UmbralPublicKey.from_bytes(alices_pubkey_bytes_saved_for_posterity)
    delivered_cleartexts = BOB.retrieve(message_kit=single_passage_ciphertext,
                                        data_source=enrico_as_understood_by_bob,
                                        alice_verifying_key=alice_pubkey_restored_from_ancient_scroll)
    # We show that indeed this is the passage originally encrypted by Enrico.
    assert plaintext == delivered_cleartexts[0]
    print("Retrieved: {}".format(delivered_cleartexts[0]))
    
    alices_verifying_key1 = ALICE.public_keys(SigningPower)
    alice_msg = ALICE.decrypt(message_kit=single_passage_ciphertext,
                              verifying_key=alices_verifying_key1)

    print('fuck ' + alice_msg)

Traceback.txt

Retrieved: b'Digitized by the Internet Archive \n'
Traceback (most recent call last):
  File "/home/salamantos/projects/dropbox_november/test.py", line 145, in <module>
    verifying_key=alices_verifying_key1)
  File "/home/salamantos/projects/dropbox_november/nucypher/characters/base.py", line 350, in decrypt
    return self._crypto_power.power_ups(EncryptingPower).decrypt(message_kit, verifying_key)
  File "/home/salamantos/projects/dropbox_november/nucypher/keystore/keypairs.py", line 104, in decrypt
    decrypting_key=self._privkey,
  File "/home/salamantos/.local/share/virtualenvs/dropbox_november-LD2SWqYs/lib/python3.7/site-packages/umbral/pre.py", line 487, in decrypt
    encapsulated_key = _open_capsule(capsule, decrypting_key, check_proof=check_proof)
  File "/home/salamantos/.local/share/virtualenvs/dropbox_november-LD2SWqYs/lib/python3.7/site-packages/umbral/pre.py", line 464, in _open_capsule
    key = _decapsulate_reencrypted(receiving_privkey, capsule)
  File "/home/salamantos/.local/share/virtualenvs/dropbox_november-LD2SWqYs/lib/python3.7/site-packages/umbral/pre.py", line 421, in _decapsulate_reencrypted
    raise GenericUmbralError()
umbral.pre.GenericUmbralError

Process finished with exit code 1