71 lines
2.1 KiB
Python
71 lines
2.1 KiB
Python
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# 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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import typing
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from cryptography import utils
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from cryptography.exceptions import AlreadyFinalized
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from cryptography.hazmat.backends.openssl.hmac import _HMACContext
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from cryptography.hazmat.primitives import hashes
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class HMAC(hashes.HashContext):
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_ctx: typing.Optional[_HMACContext]
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def __init__(
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self,
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key: bytes,
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algorithm: hashes.HashAlgorithm,
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backend: typing.Any = None,
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ctx=None,
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):
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if not isinstance(algorithm, hashes.HashAlgorithm):
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raise TypeError("Expected instance of hashes.HashAlgorithm.")
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self._algorithm = algorithm
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self._key = key
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if ctx is None:
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from cryptography.hazmat.backends.openssl.backend import (
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backend as ossl,
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)
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self._ctx = ossl.create_hmac_ctx(key, self.algorithm)
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else:
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self._ctx = ctx
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@property
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def algorithm(self) -> hashes.HashAlgorithm:
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return self._algorithm
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def update(self, data: bytes) -> None:
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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 copy(self) -> "HMAC":
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if self._ctx is None:
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raise AlreadyFinalized("Context was already finalized.")
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return HMAC(
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self._key,
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self.algorithm,
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ctx=self._ctx.copy(),
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)
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def finalize(self) -> bytes:
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if self._ctx is None:
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raise AlreadyFinalized("Context was already finalized.")
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digest = self._ctx.finalize()
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self._ctx = None
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return digest
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def verify(self, signature: bytes) -> None:
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utils._check_bytes("signature", signature)
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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(signature)
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