JezK
Edit File: poly1305.py
# This file is dual licensed under the terms of the Apache License, Version # 2.0, and the BSD License. See the LICENSE file in the root of this repository # for complete details. import typing from cryptography import utils from cryptography.exceptions import ( AlreadyFinalized, UnsupportedAlgorithm, _Reasons, ) from cryptography.hazmat.backends.openssl.poly1305 import _Poly1305Context class Poly1305: _ctx: typing.Optional[_Poly1305Context] def __init__(self, key: bytes): from cryptography.hazmat.backends.openssl.backend import backend if not backend.poly1305_supported(): raise UnsupportedAlgorithm( "poly1305 is not supported by this version of OpenSSL.", _Reasons.UNSUPPORTED_MAC, ) self._ctx = backend.create_poly1305_ctx(key) def update(self, data: bytes) -> None: if self._ctx is None: raise AlreadyFinalized("Context was already finalized.") utils._check_byteslike("data", data) self._ctx.update(data) def finalize(self) -> bytes: if self._ctx is None: raise AlreadyFinalized("Context was already finalized.") mac = self._ctx.finalize() self._ctx = None return mac def verify(self, tag: bytes) -> None: utils._check_bytes("tag", tag) if self._ctx is None: raise AlreadyFinalized("Context was already finalized.") ctx, self._ctx = self._ctx, None ctx.verify(tag) @classmethod def generate_tag(cls, key: bytes, data: bytes) -> bytes: p = Poly1305(key) p.update(data) return p.finalize() @classmethod def verify_tag(cls, key: bytes, data: bytes, tag: bytes) -> None: p = Poly1305(key) p.update(data) p.verify(tag)