mirror of https://github.com/nucypher/nucypher.git
119 lines
4.8 KiB
Python
119 lines
4.8 KiB
Python
"""
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This file is part of nucypher.
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nucypher is free software: you can redistribute it and/or modify
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it under the terms of the GNU Affero General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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nucypher is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Affero General Public License for more details.
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You should have received a copy of the GNU Affero General Public License
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along with nucypher. If not, see <https://www.gnu.org/licenses/>.
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"""
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import pytest
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from constant_sorrow import constants
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from cryptography.exceptions import InvalidSignature
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from nucypher.characters.lawful import Enrico
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"""
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What follows are various combinations of signing and encrypting, to match
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real-world scenarios.
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"""
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def test_sign_cleartext_and_encrypt(federated_alice, federated_bob):
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"""
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Exhibit One: federated_alice signs the cleartext and encrypts her signature inside
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the ciphertext.
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"""
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message = b"Have you accepted my answer on StackOverflow yet?"
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message_kit, _signature = federated_alice.encrypt_for(federated_bob, message,
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sign_plaintext=True)
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# Notice that our function still returns the signature here, in case federated_alice
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# wants to do something else with it, such as post it publicly for later
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# public verifiability.
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# However, we can expressly refrain from passing the Signature, and the
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# verification still works:
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cleartext = federated_bob.verify_from(federated_alice, message_kit, signature=None,
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decrypt=True)
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assert cleartext == message
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def test_encrypt_and_sign_the_ciphertext(federated_alice, federated_bob):
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"""
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Now, federated_alice encrypts first and then signs the ciphertext, providing a
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Signature that is completely separate from the message.
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This is useful in a scenario in which federated_bob needs to prove authenticity
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publicly without disclosing contents.
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"""
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message = b"We have a reaaall problem."
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message_kit, signature = federated_alice.encrypt_for(federated_bob, message,
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sign_plaintext=False)
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cleartext = federated_bob.verify_from(federated_alice, message_kit, signature, decrypt=True)
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assert cleartext == message
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def test_encrypt_and_sign_including_signature_in_both_places(federated_alice, federated_bob):
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"""
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Same as above, but showing that we can include the signature in both
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the plaintext (to be found upon decryption) and also passed into
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verify_from() (eg, gleaned over a side-channel).
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"""
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message = b"We have a reaaall problem."
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message_kit, signature = federated_alice.encrypt_for(federated_bob, message,
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sign_plaintext=True)
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cleartext = federated_bob.verify_from(federated_alice, message_kit, signature,
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decrypt=True)
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assert cleartext == message
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def test_encrypt_but_do_not_sign(federated_alice, federated_bob):
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"""
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Finally, federated_alice encrypts but declines to sign.
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This is useful in a scenario in which federated_alice wishes to plausibly disavow
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having created this content.
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"""
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# TODO: How do we accurately demonstrate this test safely, if at all?
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message = b"If Bonnie comes home and finds an unencrypted private key in her keystore, I'm gonna get divorced."
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# Alice might also want to encrypt a message but *not* sign it, in order
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# to refrain from creating evidence that can prove she was the
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# original sender.
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message_kit, not_signature = federated_alice.encrypt_for(federated_bob, message, sign=False)
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# The message is not signed...
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assert not_signature == constants.NOT_SIGNED
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# ...and thus, the message is not verified.
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with pytest.raises(InvalidSignature):
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federated_bob.verify_from(federated_alice, message_kit, decrypt=True)
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def test_alice_can_decrypt(federated_alice):
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label = b"boring test label"
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policy_pubkey = federated_alice.get_policy_encrypting_key_from_label(label)
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enrico = Enrico(policy_encrypting_key=policy_pubkey)
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message = b"boring test message"
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message_kit, signature = enrico.encrypt_message(plaintext=message)
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# Interesting thing: if Alice wants to decrypt, she needs to provide the label directly.
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cleartext = federated_alice.verify_from(stranger=enrico,
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message_kit=message_kit,
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signature=signature,
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decrypt=True,
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label=label)
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assert cleartext == message
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