#
# Copyright 2019 aiohomekit team
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.kdf.hkdf import HKDF

backend = default_backend()


def hkdf_derive(input: bytes, salt: bytes, info: bytes, length: int = 32) -> bytes:
    hkdf = HKDF(
        algorithm=hashes.SHA512(),
        length=length,
        salt=salt,
        info=info,
        backend=backend,
    )
    return hkdf.derive(input)