mirror of
https://github.com/thegeeklab/ansible-later.git
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134 lines
5.3 KiB
Python
134 lines
5.3 KiB
Python
# Copyright 2013 Donald Stufft and individual contributors
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#
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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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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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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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import nacl.bindings
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from nacl import encoding
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from nacl import exceptions as exc
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from nacl.utils import EncryptedMessage, StringFixer, random
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class SecretBox(encoding.Encodable, StringFixer, object):
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"""
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The SecretBox class encrypts and decrypts messages using the given secret
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key.
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The ciphertexts generated by :class:`~nacl.secret.Secretbox` 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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encryption.
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:param key: The secret key used to encrypt and decrypt messages
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:param encoder: The encoder class used to decode the given key
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:cvar KEY_SIZE: The size that the key is required to be.
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:cvar NONCE_SIZE: The size that the nonce is required to be.
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:cvar MACBYTES: The size of the authentication MAC tag in bytes.
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:cvar MESSAGEBYTES_MAX: The maximum size of a message which can be
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safely encrypted with a single key/nonce
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pair.
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"""
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KEY_SIZE = nacl.bindings.crypto_secretbox_KEYBYTES
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NONCE_SIZE = nacl.bindings.crypto_secretbox_NONCEBYTES
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MACBYTES = nacl.bindings.crypto_secretbox_MACBYTES
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MESSAGEBYTES_MAX = nacl.bindings.crypto_secretbox_MESSAGEBYTES_MAX
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def __init__(self, key, encoder=encoding.RawEncoder):
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key = encoder.decode(key)
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if not isinstance(key, bytes):
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raise exc.TypeError("SecretBox must be created from 32 bytes")
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if len(key) != self.KEY_SIZE:
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raise exc.ValueError(
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"The key must be exactly %s bytes long" %
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self.KEY_SIZE,
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)
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self._key = key
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def __bytes__(self):
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return self._key
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def encrypt(self, plaintext, nonce=None, encoder=encoding.RawEncoder):
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"""
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Encrypts the plaintext message using the given `nonce` (or generates
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one randomly if omitted) and returns the ciphertext encoded with the
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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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Give your nonces a different prefix, or have one side use an odd
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counter and one an even counter. Just make sure they are different.
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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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"""
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if nonce is None:
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nonce = random(self.NONCE_SIZE)
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if len(nonce) != self.NONCE_SIZE:
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raise exc.ValueError(
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"The nonce must be exactly %s bytes long" % self.NONCE_SIZE,
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)
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ciphertext = nacl.bindings.crypto_secretbox(plaintext,
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nonce, self._key)
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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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encoded_nonce,
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encoded_ciphertext,
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encoder.encode(nonce + ciphertext),
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)
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def decrypt(self, ciphertext, nonce=None, encoder=encoding.RawEncoder):
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"""
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Decrypts the ciphertext using the `nonce` (explicitly, when passed as a
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parameter or implicitly, when omitted, as part of the ciphertext) and
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returns the plaintext message.
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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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ciphertext
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:param encoder: The encoder used to decode the ciphertext.
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:rtype: [:class:`bytes`]
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"""
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# Decode our ciphertext
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ciphertext = encoder.decode(ciphertext)
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if nonce is None:
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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 exc.ValueError(
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"The nonce must be exactly %s bytes long" % self.NONCE_SIZE,
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)
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plaintext = nacl.bindings.crypto_secretbox_open(ciphertext,
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nonce, self._key)
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return plaintext
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