56 lines
1.6 KiB
Python
56 lines
1.6 KiB
Python
# This file is dual licensed under the terms of the Apache License, Version
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# 2.0, and the BSD License. See the LICENSE file in the root of this repository
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# for complete details.
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from __future__ import absolute_import, division, print_function
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from cryptography import utils
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from cryptography.exceptions import (
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AlreadyFinalized, UnsupportedAlgorithm, _Reasons
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)
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class Poly1305(object):
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def __init__(self, key):
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from cryptography.hazmat.backends.openssl.backend import backend
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if not backend.poly1305_supported():
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raise UnsupportedAlgorithm(
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"poly1305 is not supported by this version of OpenSSL.",
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_Reasons.UNSUPPORTED_MAC
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)
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self._ctx = backend.create_poly1305_ctx(key)
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def update(self, data):
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if self._ctx is None:
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raise AlreadyFinalized("Context was already finalized.")
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utils._check_byteslike("data", data)
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self._ctx.update(data)
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def finalize(self):
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if self._ctx is None:
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raise AlreadyFinalized("Context was already finalized.")
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mac = self._ctx.finalize()
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self._ctx = None
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return mac
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def verify(self, tag):
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utils._check_bytes("tag", tag)
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if self._ctx is None:
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raise AlreadyFinalized("Context was already finalized.")
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ctx, self._ctx = self._ctx, None
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ctx.verify(tag)
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@classmethod
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def generate_tag(cls, key, data):
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p = Poly1305(key)
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p.update(data)
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return p.finalize()
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@classmethod
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def verify_tag(cls, key, data, tag):
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p = Poly1305(key)
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p.update(data)
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p.verify(tag)
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