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Diffstat (limited to '.venv/lib/python3.12/site-packages/cryptography/hazmat/primitives/kdf/kbkdf.py')
| -rw-r--r-- | .venv/lib/python3.12/site-packages/cryptography/hazmat/primitives/kdf/kbkdf.py | 302 |
1 files changed, 302 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/cryptography/hazmat/primitives/kdf/kbkdf.py b/.venv/lib/python3.12/site-packages/cryptography/hazmat/primitives/kdf/kbkdf.py new file mode 100644 index 00000000..802b484c --- /dev/null +++ b/.venv/lib/python3.12/site-packages/cryptography/hazmat/primitives/kdf/kbkdf.py @@ -0,0 +1,302 @@ +# 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. + +from __future__ import annotations + +import typing + +from cryptography import utils +from cryptography.exceptions import ( + AlreadyFinalized, + InvalidKey, + UnsupportedAlgorithm, + _Reasons, +) +from cryptography.hazmat.primitives import ( + ciphers, + cmac, + constant_time, + hashes, + hmac, +) +from cryptography.hazmat.primitives.kdf import KeyDerivationFunction + + +class Mode(utils.Enum): + CounterMode = "ctr" + + +class CounterLocation(utils.Enum): + BeforeFixed = "before_fixed" + AfterFixed = "after_fixed" + MiddleFixed = "middle_fixed" + + +class _KBKDFDeriver: + def __init__( + self, + prf: typing.Callable, + mode: Mode, + length: int, + rlen: int, + llen: int | None, + location: CounterLocation, + break_location: int | None, + label: bytes | None, + context: bytes | None, + fixed: bytes | None, + ): + assert callable(prf) + + if not isinstance(mode, Mode): + raise TypeError("mode must be of type Mode") + + if not isinstance(location, CounterLocation): + raise TypeError("location must be of type CounterLocation") + + if break_location is None and location is CounterLocation.MiddleFixed: + raise ValueError("Please specify a break_location") + + if ( + break_location is not None + and location != CounterLocation.MiddleFixed + ): + raise ValueError( + "break_location is ignored when location is not" + " CounterLocation.MiddleFixed" + ) + + if break_location is not None and not isinstance(break_location, int): + raise TypeError("break_location must be an integer") + + if break_location is not None and break_location < 0: + raise ValueError("break_location must be a positive integer") + + if (label or context) and fixed: + raise ValueError( + "When supplying fixed data, label and context are ignored." + ) + + if rlen is None or not self._valid_byte_length(rlen): + raise ValueError("rlen must be between 1 and 4") + + if llen is None and fixed is None: + raise ValueError("Please specify an llen") + + if llen is not None and not isinstance(llen, int): + raise TypeError("llen must be an integer") + + if llen == 0: + raise ValueError("llen must be non-zero") + + if label is None: + label = b"" + + if context is None: + context = b"" + + utils._check_bytes("label", label) + utils._check_bytes("context", context) + self._prf = prf + self._mode = mode + self._length = length + self._rlen = rlen + self._llen = llen + self._location = location + self._break_location = break_location + self._label = label + self._context = context + self._used = False + self._fixed_data = fixed + + @staticmethod + def _valid_byte_length(value: int) -> bool: + if not isinstance(value, int): + raise TypeError("value must be of type int") + + value_bin = utils.int_to_bytes(1, value) + if not 1 <= len(value_bin) <= 4: + return False + return True + + def derive(self, key_material: bytes, prf_output_size: int) -> bytes: + if self._used: + raise AlreadyFinalized + + utils._check_byteslike("key_material", key_material) + self._used = True + + # inverse floor division (equivalent to ceiling) + rounds = -(-self._length // prf_output_size) + + output = [b""] + + # For counter mode, the number of iterations shall not be + # larger than 2^r-1, where r <= 32 is the binary length of the counter + # This ensures that the counter values used as an input to the + # PRF will not repeat during a particular call to the KDF function. + r_bin = utils.int_to_bytes(1, self._rlen) + if rounds > pow(2, len(r_bin) * 8) - 1: + raise ValueError("There are too many iterations.") + + fixed = self._generate_fixed_input() + + if self._location == CounterLocation.BeforeFixed: + data_before_ctr = b"" + data_after_ctr = fixed + elif self._location == CounterLocation.AfterFixed: + data_before_ctr = fixed + data_after_ctr = b"" + else: + if isinstance( + self._break_location, int + ) and self._break_location > len(fixed): + raise ValueError("break_location offset > len(fixed)") + data_before_ctr = fixed[: self._break_location] + data_after_ctr = fixed[self._break_location :] + + for i in range(1, rounds + 1): + h = self._prf(key_material) + + counter = utils.int_to_bytes(i, self._rlen) + input_data = data_before_ctr + counter + data_after_ctr + + h.update(input_data) + + output.append(h.finalize()) + + return b"".join(output)[: self._length] + + def _generate_fixed_input(self) -> bytes: + if self._fixed_data and isinstance(self._fixed_data, bytes): + return self._fixed_data + + l_val = utils.int_to_bytes(self._length * 8, self._llen) + + return b"".join([self._label, b"\x00", self._context, l_val]) + + +class KBKDFHMAC(KeyDerivationFunction): + def __init__( + self, + algorithm: hashes.HashAlgorithm, + mode: Mode, + length: int, + rlen: int, + llen: int | None, + location: CounterLocation, + label: bytes | None, + context: bytes | None, + fixed: bytes | None, + backend: typing.Any = None, + *, + break_location: int | None = None, + ): + if not isinstance(algorithm, hashes.HashAlgorithm): + raise UnsupportedAlgorithm( + "Algorithm supplied is not a supported hash algorithm.", + _Reasons.UNSUPPORTED_HASH, + ) + + from cryptography.hazmat.backends.openssl.backend import ( + backend as ossl, + ) + + if not ossl.hmac_supported(algorithm): + raise UnsupportedAlgorithm( + "Algorithm supplied is not a supported hmac algorithm.", + _Reasons.UNSUPPORTED_HASH, + ) + + self._algorithm = algorithm + + self._deriver = _KBKDFDeriver( + self._prf, + mode, + length, + rlen, + llen, + location, + break_location, + label, + context, + fixed, + ) + + def _prf(self, key_material: bytes) -> hmac.HMAC: + return hmac.HMAC(key_material, self._algorithm) + + def derive(self, key_material: bytes) -> bytes: + return self._deriver.derive(key_material, self._algorithm.digest_size) + + def verify(self, key_material: bytes, expected_key: bytes) -> None: + if not constant_time.bytes_eq(self.derive(key_material), expected_key): + raise InvalidKey + + +class KBKDFCMAC(KeyDerivationFunction): + def __init__( + self, + algorithm, + mode: Mode, + length: int, + rlen: int, + llen: int | None, + location: CounterLocation, + label: bytes | None, + context: bytes | None, + fixed: bytes | None, + backend: typing.Any = None, + *, + break_location: int | None = None, + ): + if not issubclass( + algorithm, ciphers.BlockCipherAlgorithm + ) or not issubclass(algorithm, ciphers.CipherAlgorithm): + raise UnsupportedAlgorithm( + "Algorithm supplied is not a supported cipher algorithm.", + _Reasons.UNSUPPORTED_CIPHER, + ) + + self._algorithm = algorithm + self._cipher: ciphers.BlockCipherAlgorithm | None = None + + self._deriver = _KBKDFDeriver( + self._prf, + mode, + length, + rlen, + llen, + location, + break_location, + label, + context, + fixed, + ) + + def _prf(self, _: bytes) -> cmac.CMAC: + assert self._cipher is not None + + return cmac.CMAC(self._cipher) + + def derive(self, key_material: bytes) -> bytes: + self._cipher = self._algorithm(key_material) + + assert self._cipher is not None + + from cryptography.hazmat.backends.openssl.backend import ( + backend as ossl, + ) + + if not ossl.cmac_algorithm_supported(self._cipher): + raise UnsupportedAlgorithm( + "Algorithm supplied is not a supported cipher algorithm.", + _Reasons.UNSUPPORTED_CIPHER, + ) + + return self._deriver.derive(key_material, self._cipher.block_size // 8) + + def verify(self, key_material: bytes, expected_key: bytes) -> None: + if not constant_time.bytes_eq(self.derive(key_material), expected_key): + raise InvalidKey |