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Diffstat (limited to '.venv/lib/python3.12/site-packages/cryptography/hazmat/primitives/keywrap.py')
| -rw-r--r-- | .venv/lib/python3.12/site-packages/cryptography/hazmat/primitives/keywrap.py | 177 |
1 files changed, 177 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/cryptography/hazmat/primitives/keywrap.py b/.venv/lib/python3.12/site-packages/cryptography/hazmat/primitives/keywrap.py new file mode 100644 index 00000000..b93d87d3 --- /dev/null +++ b/.venv/lib/python3.12/site-packages/cryptography/hazmat/primitives/keywrap.py @@ -0,0 +1,177 @@ +# 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.hazmat.primitives.ciphers import Cipher +from cryptography.hazmat.primitives.ciphers.algorithms import AES +from cryptography.hazmat.primitives.ciphers.modes import ECB +from cryptography.hazmat.primitives.constant_time import bytes_eq + + +def _wrap_core( + wrapping_key: bytes, + a: bytes, + r: list[bytes], +) -> bytes: + # RFC 3394 Key Wrap - 2.2.1 (index method) + encryptor = Cipher(AES(wrapping_key), ECB()).encryptor() + n = len(r) + for j in range(6): + for i in range(n): + # every encryption operation is a discrete 16 byte chunk (because + # AES has a 128-bit block size) and since we're using ECB it is + # safe to reuse the encryptor for the entire operation + b = encryptor.update(a + r[i]) + a = ( + int.from_bytes(b[:8], byteorder="big") ^ ((n * j) + i + 1) + ).to_bytes(length=8, byteorder="big") + r[i] = b[-8:] + + assert encryptor.finalize() == b"" + + return a + b"".join(r) + + +def aes_key_wrap( + wrapping_key: bytes, + key_to_wrap: bytes, + backend: typing.Any = None, +) -> bytes: + if len(wrapping_key) not in [16, 24, 32]: + raise ValueError("The wrapping key must be a valid AES key length") + + if len(key_to_wrap) < 16: + raise ValueError("The key to wrap must be at least 16 bytes") + + if len(key_to_wrap) % 8 != 0: + raise ValueError("The key to wrap must be a multiple of 8 bytes") + + a = b"\xa6\xa6\xa6\xa6\xa6\xa6\xa6\xa6" + r = [key_to_wrap[i : i + 8] for i in range(0, len(key_to_wrap), 8)] + return _wrap_core(wrapping_key, a, r) + + +def _unwrap_core( + wrapping_key: bytes, + a: bytes, + r: list[bytes], +) -> tuple[bytes, list[bytes]]: + # Implement RFC 3394 Key Unwrap - 2.2.2 (index method) + decryptor = Cipher(AES(wrapping_key), ECB()).decryptor() + n = len(r) + for j in reversed(range(6)): + for i in reversed(range(n)): + atr = ( + int.from_bytes(a, byteorder="big") ^ ((n * j) + i + 1) + ).to_bytes(length=8, byteorder="big") + r[i] + # every decryption operation is a discrete 16 byte chunk so + # it is safe to reuse the decryptor for the entire operation + b = decryptor.update(atr) + a = b[:8] + r[i] = b[-8:] + + assert decryptor.finalize() == b"" + return a, r + + +def aes_key_wrap_with_padding( + wrapping_key: bytes, + key_to_wrap: bytes, + backend: typing.Any = None, +) -> bytes: + if len(wrapping_key) not in [16, 24, 32]: + raise ValueError("The wrapping key must be a valid AES key length") + + aiv = b"\xa6\x59\x59\xa6" + len(key_to_wrap).to_bytes( + length=4, byteorder="big" + ) + # pad the key to wrap if necessary + pad = (8 - (len(key_to_wrap) % 8)) % 8 + key_to_wrap = key_to_wrap + b"\x00" * pad + if len(key_to_wrap) == 8: + # RFC 5649 - 4.1 - exactly 8 octets after padding + encryptor = Cipher(AES(wrapping_key), ECB()).encryptor() + b = encryptor.update(aiv + key_to_wrap) + assert encryptor.finalize() == b"" + return b + else: + r = [key_to_wrap[i : i + 8] for i in range(0, len(key_to_wrap), 8)] + return _wrap_core(wrapping_key, aiv, r) + + +def aes_key_unwrap_with_padding( + wrapping_key: bytes, + wrapped_key: bytes, + backend: typing.Any = None, +) -> bytes: + if len(wrapped_key) < 16: + raise InvalidUnwrap("Must be at least 16 bytes") + + if len(wrapping_key) not in [16, 24, 32]: + raise ValueError("The wrapping key must be a valid AES key length") + + if len(wrapped_key) == 16: + # RFC 5649 - 4.2 - exactly two 64-bit blocks + decryptor = Cipher(AES(wrapping_key), ECB()).decryptor() + out = decryptor.update(wrapped_key) + assert decryptor.finalize() == b"" + a = out[:8] + data = out[8:] + n = 1 + else: + r = [wrapped_key[i : i + 8] for i in range(0, len(wrapped_key), 8)] + encrypted_aiv = r.pop(0) + n = len(r) + a, r = _unwrap_core(wrapping_key, encrypted_aiv, r) + data = b"".join(r) + + # 1) Check that MSB(32,A) = A65959A6. + # 2) Check that 8*(n-1) < LSB(32,A) <= 8*n. If so, let + # MLI = LSB(32,A). + # 3) Let b = (8*n)-MLI, and then check that the rightmost b octets of + # the output data are zero. + mli = int.from_bytes(a[4:], byteorder="big") + b = (8 * n) - mli + if ( + not bytes_eq(a[:4], b"\xa6\x59\x59\xa6") + or not 8 * (n - 1) < mli <= 8 * n + or (b != 0 and not bytes_eq(data[-b:], b"\x00" * b)) + ): + raise InvalidUnwrap() + + if b == 0: + return data + else: + return data[:-b] + + +def aes_key_unwrap( + wrapping_key: bytes, + wrapped_key: bytes, + backend: typing.Any = None, +) -> bytes: + if len(wrapped_key) < 24: + raise InvalidUnwrap("Must be at least 24 bytes") + + if len(wrapped_key) % 8 != 0: + raise InvalidUnwrap("The wrapped key must be a multiple of 8 bytes") + + if len(wrapping_key) not in [16, 24, 32]: + raise ValueError("The wrapping key must be a valid AES key length") + + aiv = b"\xa6\xa6\xa6\xa6\xa6\xa6\xa6\xa6" + r = [wrapped_key[i : i + 8] for i in range(0, len(wrapped_key), 8)] + a = r.pop(0) + a, r = _unwrap_core(wrapping_key, a, r) + if not bytes_eq(a, aiv): + raise InvalidUnwrap() + + return b"".join(r) + + +class InvalidUnwrap(Exception): + pass |