217 lines
7.1 KiB
Python
217 lines
7.1 KiB
Python
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# 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.public import (PrivateKey as _Curve25519_PrivateKey,
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PublicKey as _Curve25519_PublicKey)
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from nacl.utils import StringFixer, random
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class SignedMessage(bytes):
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"""
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A bytes subclass that holds a messaged that has been signed by a
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:class:`SigningKey`.
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"""
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@classmethod
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def _from_parts(cls, signature, message, combined):
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obj = cls(combined)
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obj._signature = signature
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obj._message = message
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return obj
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@property
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def signature(self):
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"""
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The signature contained within the :class:`SignedMessage`.
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"""
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return self._signature
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@property
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def message(self):
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"""
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The message contained within the :class:`SignedMessage`.
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"""
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return self._message
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class VerifyKey(encoding.Encodable, StringFixer, object):
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"""
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The public key counterpart to an Ed25519 SigningKey for producing digital
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signatures.
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:param key: [:class:`bytes`] Serialized Ed25519 public key
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:param encoder: A class that is able to decode the `key`
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"""
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def __init__(self, key, encoder=encoding.RawEncoder):
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# Decode the key
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key = encoder.decode(key)
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if not isinstance(key, bytes):
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raise exc.TypeError("VerifyKey must be created from 32 bytes")
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if len(key) != nacl.bindings.crypto_sign_PUBLICKEYBYTES:
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raise exc.ValueError(
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"The key must be exactly %s bytes long" %
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nacl.bindings.crypto_sign_PUBLICKEYBYTES,
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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 __hash__(self):
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return hash(bytes(self))
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def __eq__(self, other):
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if not isinstance(other, self.__class__):
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return False
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return nacl.bindings.sodium_memcmp(bytes(self), bytes(other))
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def __ne__(self, other):
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return not (self == other)
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def verify(self, smessage, signature=None, encoder=encoding.RawEncoder):
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"""
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Verifies the signature of a signed message, returning the message
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if it has not been tampered with else raising
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:class:`~nacl.signing.BadSignatureError`.
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:param smessage: [:class:`bytes`] Either the original messaged or a
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signature and message concated together.
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:param signature: [:class:`bytes`] If an unsigned message is given for
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smessage then the detached signature must be provided.
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:param encoder: A class that is able to decode the secret message and
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signature.
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:rtype: :class:`bytes`
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"""
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if signature is not None:
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# If we were given the message and signature separately, combine
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# them.
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smessage = signature + smessage
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# Decode the signed message
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smessage = encoder.decode(smessage)
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return nacl.bindings.crypto_sign_open(smessage, self._key)
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def to_curve25519_public_key(self):
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"""
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Converts a :class:`~nacl.signing.VerifyKey` to a
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:class:`~nacl.public.PublicKey`
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:rtype: :class:`~nacl.public.PublicKey`
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"""
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raw_pk = nacl.bindings.crypto_sign_ed25519_pk_to_curve25519(self._key)
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return _Curve25519_PublicKey(raw_pk)
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class SigningKey(encoding.Encodable, StringFixer, object):
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"""
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Private key for producing digital signatures using the Ed25519 algorithm.
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Signing keys are produced from a 32-byte (256-bit) random seed value. This
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value can be passed into the :class:`~nacl.signing.SigningKey` as a
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:func:`bytes` whose length is 32.
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.. warning:: This **must** be protected and remain secret. Anyone who knows
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the value of your :class:`~nacl.signing.SigningKey` or it's seed can
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masquerade as you.
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:param seed: [:class:`bytes`] Random 32-byte value (i.e. private key)
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:param encoder: A class that is able to decode the seed
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:ivar: verify_key: [:class:`~nacl.signing.VerifyKey`] The verify
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(i.e. public) key that corresponds with this signing key.
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"""
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def __init__(self, seed, encoder=encoding.RawEncoder):
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# Decode the seed
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seed = encoder.decode(seed)
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if not isinstance(seed, bytes):
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raise exc.TypeError(
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"SigningKey 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(seed) != nacl.bindings.crypto_sign_SEEDBYTES:
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raise exc.ValueError(
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"The seed must be exactly %d bytes long" %
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nacl.bindings.crypto_sign_SEEDBYTES
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)
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public_key, secret_key = nacl.bindings.crypto_sign_seed_keypair(seed)
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self._seed = seed
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self._signing_key = secret_key
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self.verify_key = VerifyKey(public_key)
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def __bytes__(self):
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return self._seed
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def __hash__(self):
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return hash(bytes(self))
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def __eq__(self, other):
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if not isinstance(other, self.__class__):
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return False
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return nacl.bindings.sodium_memcmp(bytes(self), bytes(other))
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def __ne__(self, other):
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return not (self == other)
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@classmethod
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def generate(cls):
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"""
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Generates a random :class:`~nacl.signing.SigningKey` object.
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:rtype: :class:`~nacl.signing.SigningKey`
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"""
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return cls(
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random(nacl.bindings.crypto_sign_SEEDBYTES),
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encoder=encoding.RawEncoder,
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)
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def sign(self, message, encoder=encoding.RawEncoder):
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"""
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Sign a message using this key.
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:param message: [:class:`bytes`] The data to be signed.
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:param encoder: A class that is used to encode the signed message.
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:rtype: :class:`~nacl.signing.SignedMessage`
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"""
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raw_signed = nacl.bindings.crypto_sign(message, self._signing_key)
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crypto_sign_BYTES = nacl.bindings.crypto_sign_BYTES
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signature = encoder.encode(raw_signed[:crypto_sign_BYTES])
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message = encoder.encode(raw_signed[crypto_sign_BYTES:])
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signed = encoder.encode(raw_signed)
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return SignedMessage._from_parts(signature, message, signed)
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def to_curve25519_private_key(self):
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"""
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Converts a :class:`~nacl.signing.SigningKey` to a
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:class:`~nacl.public.PrivateKey`
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:rtype: :class:`~nacl.public.PrivateKey`
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"""
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sk = self._signing_key
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raw_private = nacl.bindings.crypto_sign_ed25519_sk_to_curve25519(sk)
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return _Curve25519_PrivateKey(raw_private)
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