Source code for nucypher.crypto.kits

"""
This file is part of nucypher.

nucypher is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

nucypher is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with nucypher.  If not, see <https://www.gnu.org/licenses/>.
"""
from constant_sorrow.constants import UNKNOWN_SENDER, NOT_SIGNED
from bytestring_splitter import BytestringKwargifier, VariableLengthBytestring
from nucypher.crypto.splitters import key_splitter, capsule_splitter


[docs]class CryptoKit: """ A package of discrete items, meant to be sent over the wire or saved to disk (in either case, as bytes), capable of performing a distinct cryptological function. """ splitter = None @classmethod def split_bytes(cls, some_bytes): if not cls.splitter: raise TypeError("This kit doesn't have a splitter defined.") splitter = cls.splitter() return splitter(some_bytes) @classmethod def from_bytes(cls, some_bytes): return cls.split_bytes(some_bytes)
[docs]class MessageKit(CryptoKit): """ All the components needed to transmit and verify an encrypted message. """ def __init__(self, capsule, sender_verifying_key=None, ciphertext=None, signature=NOT_SIGNED) -> None: self.ciphertext = ciphertext self.capsule = capsule self.sender_verifying_key = sender_verifying_key self._signature = signature def to_bytes(self, include_alice_pubkey=True): # We include the capsule first. as_bytes = bytes(self.capsule) # Then, before the ciphertext, we see if we're including alice's public key. # We want to put that first because it's typically of known length. if include_alice_pubkey and self.sender_verifying_key: as_bytes += bytes(self.sender_verifying_key) as_bytes += VariableLengthBytestring(self.ciphertext) return as_bytes @classmethod def splitter(cls, *args, **kwargs): return BytestringKwargifier(cls, capsule=capsule_splitter, sender_verifying_key=key_splitter, ciphertext=VariableLengthBytestring) @property def signature(self): return self._signature def __bytes__(self): return bytes(self.capsule) + VariableLengthBytestring(self.ciphertext)
[docs]class PolicyMessageKit(MessageKit): """ A MessageKit which includes sufficient additional information to be retrieved on the NuCypher Network. """ def __init__(self, *args, **kwargs): super().__init__(*args, **kwargs) self._sender = UNKNOWN_SENDER.bool_value(False) @property def sender(self): return self._sender @sender.setter def sender(self, enrico): # Here we set the delegating correctness key to the policy public key (which happens to be composed on enrico, but for which of course he doesn't have the corresponding private key). self.capsule.set_correctness_keys(delegating=enrico.policy_pubkey) self._sender = enrico def __bytes__(self): return super().to_bytes(include_alice_pubkey=True)
UmbralMessageKit = PolicyMessageKit # Temporarily, until serialization w/ Enrico's class RevocationKit: def __init__(self, policy: 'Policy', signer: 'SignatureStamp'): from nucypher.policy.collections import Revocation self.revocations = dict() for node_id, arrangement_id in policy.treasure_map: self.revocations[node_id] = Revocation(arrangement_id, signer=signer) def __iter__(self): return iter(self.revocations.values()) def __getitem__(self, node_id): return self.revocations[node_id] def __len__(self): return len(self.revocations) def __eq__(self, other): return self.revocations == other.revocations @property def revokable_addresses(self): """ Returns a Set of revokable addresses in the checksum address formatting """ return set(self.revocations.keys()) def add_confirmation(self, node_id, signed_receipt): """ Adds a signed confirmation of Ursula's ability to revoke the arrangement. """ # TODO: Verify Ursula's signature # TODO: Implement receipts raise NotImplementedError