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# Copyright 2013 Donald Stufft and individual contributors
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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# http://www.apache.org/licenses/LICENSE-2.0
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from __future__ import absolute_import, division, print_function
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from nacl import encoding
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from nacl.utils import EncryptedMessage, StringFixer, random
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class PublicKey(encoding.Encodable, StringFixer, object):
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The public key counterpart to an Curve25519 :class:`nacl.public.PrivateKey`
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for encrypting messages.
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:param public_key: [:class:`bytes`] Encoded Curve25519 public key
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:param encoder: A class that is able to decode the `public_key`
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:cvar SIZE: The size that the public key is required to be
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SIZE = nacl.bindings.crypto_box_PUBLICKEYBYTES
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def __init__(self, public_key, encoder=encoding.RawEncoder):
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self._public_key = encoder.decode(public_key)
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if not isinstance(self._public_key, bytes):
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raise TypeError("PublicKey must be created from 32 bytes")
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if len(self._public_key) != self.SIZE:
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raise ValueError("The public key must be exactly %s bytes long" %
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return self._public_key
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class PrivateKey(encoding.Encodable, StringFixer, object):
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Private key for decrypting messages using the Curve25519 algorithm.
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.. warning:: This **must** be protected and remain secret. Anyone who
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knows the value of your :class:`~nacl.public.PrivateKey` can decrypt
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any message encrypted by the corresponding
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:class:`~nacl.public.PublicKey`
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:param private_key: The private key used to decrypt messages
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:param encoder: The encoder class used to decode the given keys
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:cvar SIZE: The size that the private key is required to be
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SIZE = nacl.bindings.crypto_box_SECRETKEYBYTES
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def __init__(self, private_key, encoder=encoding.RawEncoder):
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# Decode the secret_key
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private_key = encoder.decode(private_key)
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if not isinstance(private_key, bytes):
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raise TypeError("PrivateKey must be created from a 32 byte seed")
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# Verify that our seed is the proper size
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if len(private_key) != self.SIZE:
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"The secret key must be exactly %d bytes long" % self.SIZE)
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raw_public_key = nacl.bindings.crypto_scalarmult_base(private_key)
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self._private_key = private_key
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self.public_key = PublicKey(raw_public_key)
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return self._private_key
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Generates a random :class:`~nacl.public.PrivateKey` object
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:rtype: :class:`~nacl.public.PrivateKey`
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return cls(random(PrivateKey.SIZE), encoder=encoding.RawEncoder)
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class Box(encoding.Encodable, StringFixer, object):
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The Box class boxes and unboxes messages between a pair of keys
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The ciphertexts generated by :class:`~nacl.public.Box` include a 16
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byte authenticator which is checked as part of the decryption. An invalid
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authenticator will cause the decrypt function to raise an exception. The
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authenticator is not a signature. Once you've decrypted the message you've
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demonstrated the ability to create arbitrary valid message, so messages you
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send are repudiable. For non-repudiable messages, sign them after
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:param private_key: :class:`~nacl.public.PrivateKey` used to encrypt and
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:param public_key: :class:`~nacl.public.PublicKey` used to encrypt and
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:cvar NONCE_SIZE: The size that the nonce is required to be.
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NONCE_SIZE = nacl.bindings.crypto_box_NONCEBYTES
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def __init__(self, private_key, public_key):
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if private_key and public_key:
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if ((not isinstance(private_key, PrivateKey) or
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not isinstance(public_key, PublicKey))):
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raise TypeError("Box must be created from "
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"a PrivateKey and a PublicKey")
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self._shared_key = nacl.bindings.crypto_box_beforenm(
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public_key.encode(encoder=encoding.RawEncoder),
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private_key.encode(encoder=encoding.RawEncoder),
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self._shared_key = None
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return self._shared_key
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def decode(cls, encoded, encoder=encoding.RawEncoder):
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# Create an empty box
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box = cls(None, None)
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# Assign our decoded value to the shared key of the box
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box._shared_key = encoder.decode(encoded)
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def encrypt(self, plaintext, nonce, encoder=encoding.RawEncoder):
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Encrypts the plaintext message using the given `nonce` and returns
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the ciphertext encoded with the encoder.
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.. warning:: It is **VITALLY** important that the nonce is a nonce,
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i.e. it is a number used only once for any given key. If you fail
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to do this, you compromise the privacy of the messages encrypted.
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:param plaintext: [:class:`bytes`] The plaintext message to encrypt
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:param nonce: [:class:`bytes`] The nonce to use in the encryption
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:param encoder: The encoder to use to encode the ciphertext
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:rtype: [:class:`nacl.utils.EncryptedMessage`]
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if len(nonce) != self.NONCE_SIZE:
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raise ValueError("The nonce must be exactly %s bytes long" %
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ciphertext = nacl.bindings.crypto_box_afternm(
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encoded_nonce = encoder.encode(nonce)
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encoded_ciphertext = encoder.encode(ciphertext)
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return EncryptedMessage._from_parts(
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encoder.encode(nonce + ciphertext),
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def decrypt(self, ciphertext, nonce=None, encoder=encoding.RawEncoder):
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Decrypts the ciphertext using the given nonce and returns the
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:param ciphertext: [:class:`bytes`] The encrypted message to decrypt
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:param nonce: [:class:`bytes`] The nonce used when encrypting the
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:param encoder: The encoder used to decode the ciphertext.
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:rtype: [:class:`bytes`]
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# Decode our ciphertext
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ciphertext = encoder.decode(ciphertext)
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# If we were given the nonce and ciphertext combined, split them.
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nonce = ciphertext[:self.NONCE_SIZE]
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ciphertext = ciphertext[self.NONCE_SIZE:]
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if len(nonce) != self.NONCE_SIZE:
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raise ValueError("The nonce must be exactly %s bytes long" %
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plaintext = nacl.bindings.crypto_box_open_afternm(
added
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nacl/public.py
