/usr/lib/python3/dist-packages/nacl/secret.py is in python3-nacl 1.1.2-1build1.
This file is owned by root:root, with mode 0o644.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 | # Copyright 2013 Donald Stufft and individual contributors
#
# 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.
from __future__ import absolute_import, division, print_function
import nacl.bindings
from nacl import encoding
from nacl import exceptions as exc
from nacl.utils import EncryptedMessage, StringFixer, random
class SecretBox(encoding.Encodable, StringFixer, object):
"""
The SecretBox class encrypts and decrypts messages using the given secret
key.
The ciphertexts generated by :class:`~nacl.secret.Secretbox` include a 16
byte authenticator which is checked as part of the decryption. An invalid
authenticator will cause the decrypt function to raise an exception. The
authenticator is not a signature. Once you've decrypted the message you've
demonstrated the ability to create arbitrary valid message, so messages you
send are repudiable. For non-repudiable messages, sign them after
encryption.
:param key: The secret key used to encrypt and decrypt messages
:param encoder: The encoder class used to decode the given key
:cvar KEY_SIZE: The size that the key is required to be.
:cvar NONCE_SIZE: The size that the nonce is required to be.
"""
KEY_SIZE = nacl.bindings.crypto_secretbox_KEYBYTES
NONCE_SIZE = nacl.bindings.crypto_secretbox_NONCEBYTES
def __init__(self, key, encoder=encoding.RawEncoder):
key = encoder.decode(key)
if not isinstance(key, bytes):
raise exc.TypeError("SecretBox must be created from 32 bytes")
if len(key) != self.KEY_SIZE:
raise exc.ValueError(
"The key must be exactly %s bytes long" %
self.KEY_SIZE,
)
self._key = key
def __bytes__(self):
return self._key
def encrypt(self, plaintext, nonce=None, encoder=encoding.RawEncoder):
"""
Encrypts the plaintext message using the given `nonce` (or generates
one randomly if omitted) and returns the ciphertext encoded with the
encoder.
.. warning:: It is **VITALLY** important that the nonce is a nonce,
i.e. it is a number used only once for any given key. If you fail
to do this, you compromise the privacy of the messages encrypted.
Give your nonces a different prefix, or have one side use an odd
counter and one an even counter. Just make sure they are different.
:param plaintext: [:class:`bytes`] The plaintext message to encrypt
:param nonce: [:class:`bytes`] The nonce to use in the encryption
:param encoder: The encoder to use to encode the ciphertext
:rtype: [:class:`nacl.utils.EncryptedMessage`]
"""
if nonce is None:
nonce = random(self.NONCE_SIZE)
if len(nonce) != self.NONCE_SIZE:
raise exc.ValueError(
"The nonce must be exactly %s bytes long" % self.NONCE_SIZE,
)
ciphertext = nacl.bindings.crypto_secretbox(plaintext,
nonce, self._key)
encoded_nonce = encoder.encode(nonce)
encoded_ciphertext = encoder.encode(ciphertext)
return EncryptedMessage._from_parts(
encoded_nonce,
encoded_ciphertext,
encoder.encode(nonce + ciphertext),
)
def decrypt(self, ciphertext, nonce=None, encoder=encoding.RawEncoder):
"""
Decrypts the ciphertext using the `nonce` (explicitly, when passed as a
parameter or implicitly, when omitted, as part of the ciphertext) and
returns the plaintext message.
:param ciphertext: [:class:`bytes`] The encrypted message to decrypt
:param nonce: [:class:`bytes`] The nonce used when encrypting the
ciphertext
:param encoder: The encoder used to decode the ciphertext.
:rtype: [:class:`bytes`]
"""
# Decode our ciphertext
ciphertext = encoder.decode(ciphertext)
if nonce is None:
# If we were given the nonce and ciphertext combined, split them.
nonce = ciphertext[:self.NONCE_SIZE]
ciphertext = ciphertext[self.NONCE_SIZE:]
if len(nonce) != self.NONCE_SIZE:
raise exc.ValueError(
"The nonce must be exactly %s bytes long" % self.NONCE_SIZE,
)
plaintext = nacl.bindings.crypto_secretbox_open(ciphertext,
nonce, self._key)
return plaintext
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