moving to scripts

asq-env/lib/python3.9/site-packages/cryptography/hazmat/primitives/kdf/x963kdf.py

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+# 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 struct
+import typing
+
+from cryptography import utils
+from cryptography.exceptions import (
+    AlreadyFinalized,
+    InvalidKey,
+    UnsupportedAlgorithm,
+    _Reasons,
+)
+from cryptography.hazmat.backends import _get_backend
+from cryptography.hazmat.backends.interfaces import Backend, HashBackend
+from cryptography.hazmat.primitives import constant_time, hashes
+from cryptography.hazmat.primitives.kdf import KeyDerivationFunction
+
+
+def _int_to_u32be(n):
+    return struct.pack(">I", n)
+
+
+class X963KDF(KeyDerivationFunction):
+    def __init__(
+        self,
+        algorithm: hashes.HashAlgorithm,
+        length: int,
+        sharedinfo: typing.Optional[bytes],
+        backend: typing.Optional[Backend] = None,
+    ):
+        backend = _get_backend(backend)
+
+        max_len = algorithm.digest_size * (2 ** 32 - 1)
+        if length > max_len:
+            raise ValueError(
+                "Cannot derive keys larger than {} bits.".format(max_len)
+            )
+        if sharedinfo is not None:
+            utils._check_bytes("sharedinfo", sharedinfo)
+
+        self._algorithm = algorithm
+        self._length = length
+        self._sharedinfo = sharedinfo
+
+        if not isinstance(backend, HashBackend):
+            raise UnsupportedAlgorithm(
+                "Backend object does not implement HashBackend.",
+                _Reasons.BACKEND_MISSING_INTERFACE,
+            )
+        self._backend = backend
+        self._used = False
+
+    def derive(self, key_material: bytes) -> bytes:
+        if self._used:
+            raise AlreadyFinalized
+        self._used = True
+        utils._check_byteslike("key_material", key_material)
+        output = [b""]
+        outlen = 0
+        counter = 1
+
+        while self._length > outlen:
+            h = hashes.Hash(self._algorithm, self._backend)
+            h.update(key_material)
+            h.update(_int_to_u32be(counter))
+            if self._sharedinfo is not None:
+                h.update(self._sharedinfo)
+            output.append(h.finalize())
+            outlen += len(output[-1])
+            counter += 1
+
+        return b"".join(output)[: self._length]
+
+    def verify(self, key_material: bytes, expected_key: bytes) -> None:
+        if not constant_time.bytes_eq(self.derive(key_material), expected_key):
+            raise InvalidKey