Method encrypt

pgpy/pgp.py:2499–2564

encrypt(message[, sessionkey=None], **prefs) Encrypt a PGPMessage using this key. :param message: The message to encrypt. :type message: :py:obj:`PGPMessage` :param sessionkey: Provide a session key to use when encrypting something. Default is ``None``.

(self, message, sessionkey=None, **prefs)

    @KeyAction(KeyFlags.EncryptCommunications, KeyFlags.EncryptStorage, is_public=True)
    def encrypt(self, message, sessionkey=None, **prefs):
        """encrypt(message[, sessionkey=None], **prefs)

        Encrypt a PGPMessage using this key.

        :param message: The message to encrypt.
        :type message: :py:obj:`PGPMessage`
        :param sessionkey: Provide a session key to use when encrypting something. Default is ``None``.
                                    If ``None``, a session key of the appropriate length will be generated randomly.

                                    .. warning::

                                        Care should be taken when making use of this option! Session keys *absolutely need*
                                        to be unpredictable! Use the ``gen_key()`` method on the desired
                                        :py:obj:`~constants.SymmetricKeyAlgorithm` to generate the session key!
        :type sessionkey: ``bytes``, ``str``

        :raises: :py:exc:`~errors.PGPEncryptionError` if encryption failed for any reason.
        :returns: A new :py:obj:`PGPMessage` with the encrypted contents of ``message``

        The following optional keyword arguments can be used with :py:meth:`PGPKey.encrypt`:

        :keyword cipher: Specifies the symmetric block cipher to use when encrypting the message.
        :type cipher: :py:obj:`~constants.SymmetricKeyAlgorithm`
        :keyword user: Specifies the User ID to use as the recipient for this encryption operation, for the purposes of
                       preference defaults and selection validation.
        :type user: ``str``, ``unicode``
        """
        user = prefs.pop('user', None)
        uid = None
        if user is not None:
            uid = self.get_uid(user)
        else:
            uid = next(iter(self.userids), None)
            if uid is None and self.parent is not None:
                uid = next(iter(self.parent.userids), None)
        pref_cipher = next((c for c in uid.selfsig.cipherprefs if c.is_supported), SymmetricKeyAlgorithm.TripleDES)
        cipher_algo = prefs.pop('cipher', pref_cipher)

        if cipher_algo not in uid.selfsig.cipherprefs:
            warnings.warn("Selected symmetric algorithm not in key preferences", stacklevel=3)

        if message.is_compressed and message._compression not in uid.selfsig.compprefs:
            warnings.warn("Selected compression algorithm not in key preferences", stacklevel=3)

        if sessionkey is None:
            sessionkey = cipher_algo.gen_key()

        # set up a new PKESessionKeyV3
        pkesk = PKESessionKeyV3()
        pkesk.encrypter = bytearray(binascii.unhexlify(self.fingerprint.keyid.encode('latin-1')))
        pkesk.pkalg = self.key_algorithm
        pkesk.encrypt_sk(self._key, cipher_algo, sessionkey)

        if message.is_encrypted:  # pragma: no cover
            _m = message

        else: