# -*- coding: utf-8 -*- # libolm python bindings # Copyright © 2015-2017 OpenMarket Ltd # Copyright © 2018 Damir Jelić # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. """libolm Account module. This module contains the account part of the Olm library. It contains a single Account class which handles the creation of new accounts as well as the storing and restoring of them. Examples: >>> acc = Account() >>> account.identity_keys() >>> account.generate_one_time_keys(1) """ import json # pylint: disable=redefined-builtin,unused-import from builtins import bytes, super from typing import AnyStr, Dict, Optional, Type from future.utils import bytes_to_native_str # pylint: disable=no-name-in-module from _libolm import ffi, lib # type: ignore from ._compat import URANDOM, to_bytearray from ._finalize import track_for_finalization # This is imported only for type checking purposes if False: from .session import Session # pragma: no cover def _clear_account(account): # type: (ffi.cdata) -> None lib.olm_clear_account(account) class OlmAccountError(Exception): """libolm Account error exception.""" class Account(object): """libolm Account class.""" def __new__(cls): # type: (Type[Account]) -> Account obj = super().__new__(cls) obj._buf = ffi.new("char[]", lib.olm_account_size()) obj._account = lib.olm_account(obj._buf) track_for_finalization(obj, obj._account, _clear_account) return obj def __init__(self): # type: () -> None """Create a new Olm account. Creates a new account and its matching identity key pair. Raises OlmAccountError on failure. If there weren't enough random bytes for the account creation the error message for the exception will be NOT_ENOUGH_RANDOM. """ # This is needed to silence mypy not knowing the type of _account. # There has to be a better way for this. if False: # pragma: no cover self._account = self._account # type: ffi.cdata random_length = lib.olm_create_account_random_length(self._account) random = URANDOM(random_length) self._check_error( lib.olm_create_account(self._account, ffi.from_buffer(random), random_length)) def _check_error(self, ret): # type: (int) -> None if ret != lib.olm_error(): return last_error = bytes_to_native_str( ffi.string((lib.olm_account_last_error(self._account)))) raise OlmAccountError(last_error) def pickle(self, passphrase=""): # type: (Optional[str]) -> bytes """Store an Olm account. Stores an account as a base64 string. Encrypts the account using the supplied passphrase. Returns a byte object containing the base64 encoded string of the pickled account. Raises OlmAccountError on failure. Args: passphrase(str, optional): The passphrase to be used to encrypt the account. """ byte_key = bytearray(passphrase, "utf-8") if passphrase else b"" pickle_length = lib.olm_pickle_account_length(self._account) pickle_buffer = ffi.new("char[]", pickle_length) try: self._check_error( lib.olm_pickle_account(self._account, ffi.from_buffer(byte_key), len(byte_key), pickle_buffer, pickle_length)) finally: # zero out copies of the passphrase for i in range(0, len(byte_key)): byte_key[i] = 0 return ffi.unpack(pickle_buffer, pickle_length) @classmethod def from_pickle(cls, pickle, passphrase=""): # type: (bytes, Optional[str]) -> Account """Load a previously stored olm account. Loads an account from a pickled base64-encoded string and returns an Account object. Decrypts the account using the supplied passphrase. Raises OlmAccountError on failure. If the passphrase doesn't match the one used to encrypt the account then the error message for the exception will be "BAD_ACCOUNT_KEY". If the base64 couldn't be decoded then the error message will be "INVALID_BASE64". Args: pickle(bytes): Base64 encoded byte string containing the pickled account passphrase(str, optional): The passphrase used to encrypt the account. """ if not pickle: raise ValueError("Pickle can't be empty") byte_key = bytearray(passphrase, "utf-8") if passphrase else b"" # copy because unpickle will destroy the buffer pickle_buffer = ffi.new("char[]", pickle) obj = cls.__new__(cls) try: ret = lib.olm_unpickle_account(obj._account, ffi.from_buffer(byte_key), len(byte_key), pickle_buffer, len(pickle)) obj._check_error(ret) finally: for i in range(0, len(byte_key)): byte_key[i] = 0 return obj @property def identity_keys(self): # type: () -> Dict[str, str] """dict: Public part of the identity keys of the account.""" out_length = lib.olm_account_identity_keys_length(self._account) out_buffer = ffi.new("char[]", out_length) self._check_error( lib.olm_account_identity_keys(self._account, out_buffer, out_length)) return json.loads(ffi.unpack(out_buffer, out_length).decode("utf-8")) def sign(self, message): # type: (AnyStr) -> str """Signs a message with this account. Signs a message with the private ed25519 identity key of this account. Returns the signature. Raises OlmAccountError on failure. Args: message(str): The message to sign. """ bytes_message = to_bytearray(message) out_length = lib.olm_account_signature_length(self._account) out_buffer = ffi.new("char[]", out_length) try: self._check_error( lib.olm_account_sign(self._account, ffi.from_buffer(bytes_message), len(bytes_message), out_buffer, out_length)) finally: # clear out copies of the message, which may be plaintext if bytes_message is not message: for i in range(0, len(bytes_message)): bytes_message[i] = 0 return bytes_to_native_str(ffi.unpack(out_buffer, out_length)) @property def max_one_time_keys(self): # type: () -> int """int: The maximum number of one-time keys the account can store.""" return lib.olm_account_max_number_of_one_time_keys(self._account) def mark_keys_as_published(self): # type: () -> None """Mark the current set of one-time keys as being published.""" lib.olm_account_mark_keys_as_published(self._account) def generate_one_time_keys(self, count): # type: (int) -> None """Generate a number of new one-time keys. If the total number of keys stored by this account exceeds max_one_time_keys() then the old keys are discarded. Raises OlmAccountError on error. Args: count(int): The number of keys to generate. """ random_length = lib.olm_account_generate_one_time_keys_random_length( self._account, count) random = URANDOM(random_length) self._check_error( lib.olm_account_generate_one_time_keys( self._account, count, ffi.from_buffer(random), random_length)) @property def one_time_keys(self): # type: () -> Dict[str, Dict[str, str]] """dict: The public part of the one-time keys for this account.""" out_length = lib.olm_account_one_time_keys_length(self._account) out_buffer = ffi.new("char[]", out_length) self._check_error( lib.olm_account_one_time_keys(self._account, out_buffer, out_length)) return json.loads(ffi.unpack(out_buffer, out_length).decode("utf-8")) def remove_one_time_keys(self, session): # type: (Session) -> None """Remove used one-time keys. Removes the one-time keys that the session used from the account. Raises OlmAccountError on failure. If the account doesn't have any matching one-time keys then the error message of the exception will be "BAD_MESSAGE_KEY_ID". Args: session(Session): An Olm Session object that was created with this account. """ self._check_error(lib.olm_remove_one_time_keys(self._account, session._session))