mirror of
https://github.com/OpenKMIP/PyKMIP.git
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a4b7b433b4
This change adds the Decrypt operation to the server. Support is currently limited to symmetric decryption only. The decryption key used with the operation must be in the Active state and it must have the Decrypt bit set in its cryptographic usage mask.
871 lines
36 KiB
Python
871 lines
36 KiB
Python
# Copyright (c) 2016 The Johns Hopkins University/Applied Physics Laboratory
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import logging
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import os
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from cryptography.hazmat.backends import default_backend
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from cryptography.hazmat.primitives import serialization, hashes, hmac, cmac
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from cryptography.hazmat.primitives import padding as symmetric_padding
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from cryptography.hazmat.primitives.asymmetric import rsa
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from cryptography.hazmat.primitives.asymmetric import padding as \
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asymmetric_padding
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from cryptography.hazmat.primitives import ciphers, keywrap
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from cryptography.hazmat.primitives.ciphers import algorithms, modes
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from cryptography.hazmat.primitives.kdf import hkdf
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from cryptography.hazmat.primitives.kdf import kbkdf
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from cryptography.hazmat.primitives.kdf import pbkdf2
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from kmip.core import enums
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from kmip.core import exceptions
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from kmip.services.server.crypto import api
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class CryptographyEngine(api.CryptographicEngine):
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"""
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A cryptographic engine that uses pyca/cryptography to generate
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cryptographic objects and conduct cryptographic operations.
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"""
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def __init__(self):
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"""
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Construct a CryptographyEngine.
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"""
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self.logger = logging.getLogger('kmip.server.engine.cryptography')
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# The IDEA algorithm is supported by cryptography but may not be
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# supported by certain backends, like OpenSSL.
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self._symmetric_key_algorithms = {
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enums.CryptographicAlgorithm.TRIPLE_DES: algorithms.TripleDES,
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enums.CryptographicAlgorithm.AES: algorithms.AES,
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enums.CryptographicAlgorithm.BLOWFISH: algorithms.Blowfish,
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enums.CryptographicAlgorithm.CAMELLIA: algorithms.Camellia,
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enums.CryptographicAlgorithm.CAST5: algorithms.CAST5,
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enums.CryptographicAlgorithm.IDEA: algorithms.IDEA,
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enums.CryptographicAlgorithm.RC4: algorithms.ARC4
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}
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self._asymmetric_key_algorithms = {
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enums.CryptographicAlgorithm.RSA: self._create_rsa_key_pair
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}
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self._hash_algorithms = {
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enums.CryptographicAlgorithm.HMAC_SHA1: hashes.SHA1,
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enums.CryptographicAlgorithm.HMAC_SHA224: hashes.SHA224,
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enums.CryptographicAlgorithm.HMAC_SHA256: hashes.SHA256,
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enums.CryptographicAlgorithm.HMAC_SHA384: hashes.SHA384,
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enums.CryptographicAlgorithm.HMAC_SHA512: hashes.SHA512,
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enums.CryptographicAlgorithm.HMAC_MD5: hashes.MD5
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}
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# TODO(peter-hamilton): Consider merging above hash dict and this one
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self._encryption_hash_algorithms = {
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enums.HashingAlgorithm.MD5: hashes.MD5,
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enums.HashingAlgorithm.SHA_1: hashes.SHA1,
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enums.HashingAlgorithm.SHA_224: hashes.SHA224,
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enums.HashingAlgorithm.SHA_256: hashes.SHA256,
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enums.HashingAlgorithm.SHA_384: hashes.SHA384,
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enums.HashingAlgorithm.SHA_512: hashes.SHA512
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}
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# GCM is supported by cryptography but requires inputs that are not
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# supported by the KMIP spec. It is excluded for now.
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self._modes = {
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enums.BlockCipherMode.CBC: modes.CBC,
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enums.BlockCipherMode.ECB: modes.ECB,
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enums.BlockCipherMode.OFB: modes.OFB,
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enums.BlockCipherMode.CFB: modes.CFB,
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enums.BlockCipherMode.CTR: modes.CTR
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}
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self._asymmetric_padding_methods = {
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enums.PaddingMethod.OAEP: asymmetric_padding.OAEP,
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enums.PaddingMethod.PKCS1v15: asymmetric_padding.PKCS1v15
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}
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self._symmetric_padding_methods = {
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enums.PaddingMethod.ANSI_X923: symmetric_padding.ANSIX923,
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enums.PaddingMethod.PKCS5: symmetric_padding.PKCS7
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}
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self._no_mode_needed = [
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enums.CryptographicAlgorithm.RC4
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]
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self._no_padding_needed = [
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enums.BlockCipherMode.CTR,
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enums.BlockCipherMode.OFB,
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enums.BlockCipherMode.CFB,
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enums.BlockCipherMode.GCM
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]
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def create_symmetric_key(self, algorithm, length):
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"""
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Create a symmetric key.
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Args:
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algorithm(CryptographicAlgorithm): An enumeration specifying the
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algorithm for which the created key will be compliant.
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length(int): The length of the key to be created. This value must
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be compliant with the constraints of the provided algorithm.
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Returns:
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dict: A dictionary containing the key data, with the following
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key/value fields:
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* value - the bytes of the key
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* format - a KeyFormatType enumeration for the bytes format
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Raises:
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InvalidField: Raised when the algorithm is unsupported or the
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length is incompatible with the algorithm.
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CryptographicFailure: Raised when the key generation process
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fails.
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Example:
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>>> engine = CryptographyEngine()
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>>> key = engine.create_symmetric_key(
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... CryptographicAlgorithm.AES, 256)
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"""
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if algorithm not in self._symmetric_key_algorithms.keys():
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raise exceptions.InvalidField(
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"The cryptographic algorithm {0} is not a supported symmetric "
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"key algorithm.".format(algorithm)
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)
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cryptography_algorithm = self._symmetric_key_algorithms.get(algorithm)
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if length not in cryptography_algorithm.key_sizes:
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raise exceptions.InvalidField(
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"The cryptographic length ({0}) is not valid for "
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"the cryptographic algorithm ({1}).".format(
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length, algorithm.name
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)
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)
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self.logger.info(
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"Generating a {0} symmetric key with length: {1}".format(
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algorithm.name, length
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)
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)
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key_bytes = os.urandom(length // 8)
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try:
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cryptography_algorithm(key_bytes)
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except Exception as e:
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self.logger.exception(e)
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raise exceptions.CryptographicFailure(
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"Invalid bytes for the provided cryptographic algorithm.")
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return {'value': key_bytes, 'format': enums.KeyFormatType.RAW}
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def create_asymmetric_key_pair(self, algorithm, length):
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"""
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Create an asymmetric key pair.
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Args:
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algorithm(CryptographicAlgorithm): An enumeration specifying the
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algorithm for which the created keys will be compliant.
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length(int): The length of the keys to be created. This value must
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be compliant with the constraints of the provided algorithm.
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Returns:
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dict: A dictionary containing the public key data, with at least
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the following key/value fields:
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* value - the bytes of the key
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* format - a KeyFormatType enumeration for the bytes format
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dict: A dictionary containing the private key data, identical in
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structure to the one above.
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Raises:
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InvalidField: Raised when the algorithm is unsupported or the
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length is incompatible with the algorithm.
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CryptographicFailure: Raised when the key generation process
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fails.
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Example:
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>>> engine = CryptographyEngine()
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>>> key = engine.create_asymmetric_key(
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... CryptographicAlgorithm.RSA, 2048)
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"""
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if algorithm not in self._asymmetric_key_algorithms.keys():
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raise exceptions.InvalidField(
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"The cryptographic algorithm ({0}) is not a supported "
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"asymmetric key algorithm.".format(algorithm)
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)
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engine_method = self._asymmetric_key_algorithms.get(algorithm)
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return engine_method(length)
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def mac(self, algorithm, key, data):
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"""
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Generate message authentication code.
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Args:
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algorithm(CryptographicAlgorithm): An enumeration specifying the
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algorithm for which the MAC operation will use.
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key(bytes): secret key used in the MAC operation
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data(bytes): The data to be MACed.
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Returns:
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bytes: The MACed data
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Raises:
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InvalidField: Raised when the algorithm is unsupported or the
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length is incompatible with the algorithm.
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CryptographicFailure: Raised when the key generation process
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fails.
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Example:
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>>> engine = CryptographyEngine()
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>>> mac_data = engine.mac(
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... CryptographicAlgorithm.HMAC-SHA256, b'\x01\x02\x03\x04',
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... b'\x05\x06\x07\x08')
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"""
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mac_data = None
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if algorithm in self._hash_algorithms.keys():
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self.logger.info(
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"Generating a hash-based message authentication code using "
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"{0}".format(algorithm.name)
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)
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hash_algorithm = self._hash_algorithms.get(algorithm)
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try:
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h = hmac.HMAC(key, hash_algorithm(), backend=default_backend())
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h.update(data)
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mac_data = h.finalize()
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except Exception as e:
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self.logger.exception(e)
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raise exceptions.CryptographicFailure(
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"An error occurred while computing an HMAC. "
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"See the server log for more information."
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)
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elif algorithm in self._symmetric_key_algorithms.keys():
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self.logger.info(
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"Generating a cipher-based message authentication code using "
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"{0}".format(algorithm.name)
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)
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cipher_algorithm = self._symmetric_key_algorithms.get(algorithm)
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try:
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# ARC4 and IDEA algorithms will raise exception as CMAC
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# requires block ciphers
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c = cmac.CMAC(cipher_algorithm(key), backend=default_backend())
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c.update(data)
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mac_data = c.finalize()
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except Exception as e:
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raise exceptions.CryptographicFailure(
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"An error occurred while computing a CMAC. "
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"See the server log for more information."
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)
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else:
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raise exceptions.InvalidField(
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"The cryptographic algorithm ({0}) is not a supported "
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"for a MAC operation.".format(algorithm)
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)
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return mac_data
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def encrypt(self,
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encryption_algorithm,
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encryption_key,
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plain_text,
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cipher_mode=None,
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padding_method=None,
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iv_nonce=None):
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"""
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Encrypt data using symmetric encryption.
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Args:
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encryption_algorithm (CryptographicAlgorithm): An enumeration
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specifying the symmetric encryption algorithm to use for
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encryption.
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encryption_key (bytes): The bytes of the symmetric key to use for
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encryption.
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plain_text (bytes): The bytes to be encrypted.
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cipher_mode (BlockCipherMode): An enumeration specifying the
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block cipher mode to use with the encryption algorithm.
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Required in the general case. Optional if the encryption
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algorithm is RC4 (aka ARC4). If optional, defaults to None.
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padding_method (PaddingMethod): An enumeration specifying the
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padding method to use on the data before encryption. Required
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if the cipher mode is for block ciphers (e.g., CBC, ECB).
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Optional otherwise, defaults to None.
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iv_nonce (bytes): The IV/nonce value to use to initialize the mode
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of the encryption algorithm. Optional, defaults to None. If
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required and not provided, it will be autogenerated and
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returned with the cipher text.
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Returns:
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dict: A dictionary containing the encrypted data, with at least
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the following key/value fields:
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* cipher_text - the bytes of the encrypted data
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* iv_nonce - the bytes of the IV/counter/nonce used if it
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was needed by the encryption scheme and if it was
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automatically generated for the encryption
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Raises:
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InvalidField: Raised when the algorithm is unsupported or the
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length is incompatible with the algorithm.
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CryptographicFailure: Raised when the key generation process
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fails.
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Example:
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>>> engine = CryptographyEngine()
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>>> result = engine.encrypt(
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... encryption_algorithm=CryptographicAlgorithm.AES,
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... encryption_key=(
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... b'\xF3\x96\xE7\x1C\xCF\xCD\xEC\x1F'
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... b'\xFC\xE2\x8E\xA6\xF8\x74\x28\xB0'
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... ),
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... plain_text=(
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... b'\x00\x01\x02\x03\x04\x05\x06\x07'
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... b'\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F'
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... ),
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... cipher_mode=BlockCipherMode.CBC,
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... padding_method=PaddingMethod.ANSI_X923,
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... )
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>>> result.get('cipher_text')
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b'\x18[\xb9y\x1bL\xd1\x8f\x9a\xa0e\x02b\xa3=c'
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>>> result.iv_counter_nonce
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b'8qA\x05\xc4\x86\x03\xd9=\xef\xdf\xb8ke\x9a\xa2'
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"""
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# Set up the algorithm
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if encryption_algorithm is None:
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raise exceptions.InvalidField("Encryption algorithm is required.")
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algorithm = self._symmetric_key_algorithms.get(
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encryption_algorithm,
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None
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)
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if algorithm is None:
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raise exceptions.InvalidField(
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"Encryption algorithm '{0}' is not a supported symmetric "
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"encryption algorithm.".format(encryption_algorithm)
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)
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try:
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algorithm = algorithm(encryption_key)
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except Exception as e:
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self.logger.exception(e)
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raise exceptions.CryptographicFailure(
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"Invalid key bytes for the specified encryption algorithm."
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)
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# Set up the cipher mode if needed
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return_iv_nonce = False
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if encryption_algorithm == enums.CryptographicAlgorithm.RC4:
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mode = None
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else:
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if cipher_mode is None:
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raise exceptions.InvalidField("Cipher mode is required.")
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mode = self._modes.get(cipher_mode, None)
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if mode is None:
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raise exceptions.InvalidField(
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"Cipher mode '{0}' is not a supported mode.".format(
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cipher_mode
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)
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)
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if hasattr(mode, 'initialization_vector') or \
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hasattr(mode, 'nonce'):
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if iv_nonce is None:
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iv_nonce = os.urandom(algorithm.block_size // 8)
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return_iv_nonce = True
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mode = mode(iv_nonce)
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else:
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mode = mode()
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# Pad the plain text if needed (separate methods for testing purposes)
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if cipher_mode in [
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enums.BlockCipherMode.CBC,
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enums.BlockCipherMode.ECB
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]:
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plain_text = self._handle_symmetric_padding(
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self._symmetric_key_algorithms.get(encryption_algorithm),
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plain_text,
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padding_method
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)
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# Encrypt the plain text
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cipher = ciphers.Cipher(algorithm, mode, backend=default_backend())
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encryptor = cipher.encryptor()
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cipher_text = encryptor.update(plain_text) + encryptor.finalize()
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if return_iv_nonce:
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return {
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'cipher_text': cipher_text,
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'iv_nonce': iv_nonce
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}
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else:
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return {'cipher_text': cipher_text}
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def _handle_symmetric_padding(self,
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algorithm,
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plain_text,
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padding_method,
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undo_padding=False):
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# KMIP 1.3 test TC-STREAM-ENC-2-13.xml demonstrates a case
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# where an encrypt call for 3DES-ECB does not use padding if
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# the plaintext fits the blocksize of the algorithm. This does
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# not appear to be documented explicitly in the KMIP spec. It
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# also makes failures during unpadding after decryption
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# impossible to differentiate from cipher text/key mismatches.
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# For now, ALWAYS apply padding regardless of plain text length.
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if padding_method in self._symmetric_padding_methods.keys():
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padding_method = self._symmetric_padding_methods.get(
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padding_method
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)
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if undo_padding:
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padder = padding_method(algorithm.block_size).unpadder()
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else:
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padder = padding_method(algorithm.block_size).padder()
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plain_text = padder.update(plain_text)
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plain_text += padder.finalize()
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else:
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if padding_method is None:
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raise exceptions.InvalidField(
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"Padding method is required."
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)
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else:
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raise exceptions.InvalidField(
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"Padding method '{0}' is not supported.".format(
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padding_method
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)
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)
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return plain_text
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def decrypt(self,
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decryption_algorithm,
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decryption_key,
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cipher_text,
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cipher_mode=None,
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padding_method=None,
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iv_nonce=None):
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"""
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Decrypt data using symmetric decryption.
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Args:
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decryption_algorithm (CryptographicAlgorithm): An enumeration
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specifying the symmetric decryption algorithm to use for
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decryption.
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decryption_key (bytes): The bytes of the symmetric key to use for
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decryption.
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cipher_text (bytes): The bytes to be decrypted.
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cipher_mode (BlockCipherMode): An enumeration specifying the
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block cipher mode to use with the decryption algorithm.
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Required in the general case. Optional if the decryption
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algorithm is RC4 (aka ARC4). If optional, defaults to None.
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padding_method (PaddingMethod): An enumeration specifying the
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padding method to use on the data after decryption. Required
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if the cipher mode is for block ciphers (e.g., CBC, ECB).
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Optional otherwise, defaults to None.
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iv_nonce (bytes): The IV/nonce value to use to initialize the mode
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of the decryption algorithm. Optional, defaults to None.
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Returns:
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bytes: the bytes of the decrypted data
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Raises:
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InvalidField: Raised when the algorithm is unsupported or the
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length is incompatible with the algorithm.
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CryptographicFailure: Raised when the key generation process
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fails.
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Example:
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>>> engine = CryptographyEngine()
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>>> result = engine.decrypt(
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... decryption_algorithm=CryptographicAlgorithm.AES,
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... decryption_key=(
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... b'\xF3\x96\xE7\x1C\xCF\xCD\xEC\x1F'
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... b'\xFC\xE2\x8E\xA6\xF8\x74\x28\xB0'
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... ),
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... cipher_text=(
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... b'\x18\x5B\xB9\x79\x1B\x4C\xD1\x8F'
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... b'\x9A\xA0\x65\x02\x62\xA3\x3D\x63'
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... ),
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... cipher_mode=BlockCipherMode.CBC,
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... padding_method=PaddingMethod.ANSI_X923,
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... iv_nonce=(
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... b'\x38\x71\x41\x05\xC4\x86\x03\xD9'
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... b'\x3D\xEF\xDF\xB8\x6B\x65\x9A\xA2'
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... )
|
|
... )
|
|
>>> result
|
|
b'\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f'
|
|
"""
|
|
|
|
# Set up the algorithm
|
|
if decryption_algorithm is None:
|
|
raise exceptions.InvalidField("Decryption algorithm is required.")
|
|
algorithm = self._symmetric_key_algorithms.get(
|
|
decryption_algorithm,
|
|
None
|
|
)
|
|
if algorithm is None:
|
|
raise exceptions.InvalidField(
|
|
"Decryption algorithm '{0}' is not a supported symmetric "
|
|
"decryption algorithm.".format(decryption_algorithm)
|
|
)
|
|
try:
|
|
algorithm = algorithm(decryption_key)
|
|
except Exception as e:
|
|
self.logger.exception(e)
|
|
raise exceptions.CryptographicFailure(
|
|
"Invalid key bytes for the specified decryption algorithm."
|
|
)
|
|
|
|
# Set up the cipher mode if needed
|
|
if decryption_algorithm == enums.CryptographicAlgorithm.RC4:
|
|
mode = None
|
|
else:
|
|
if cipher_mode is None:
|
|
raise exceptions.InvalidField("Cipher mode is required.")
|
|
mode = self._modes.get(cipher_mode, None)
|
|
if mode is None:
|
|
raise exceptions.InvalidField(
|
|
"Cipher mode '{0}' is not a supported mode.".format(
|
|
cipher_mode
|
|
)
|
|
)
|
|
if hasattr(mode, 'initialization_vector') or \
|
|
hasattr(mode, 'nonce'):
|
|
if iv_nonce is None:
|
|
raise exceptions.InvalidField(
|
|
"IV/nonce is required."
|
|
)
|
|
mode = mode(iv_nonce)
|
|
else:
|
|
mode = mode()
|
|
|
|
# Decrypt the plain text
|
|
cipher = ciphers.Cipher(algorithm, mode, backend=default_backend())
|
|
decryptor = cipher.decryptor()
|
|
plain_text = decryptor.update(cipher_text) + decryptor.finalize()
|
|
|
|
# Unpad the plain text if needed (separate methods for testing
|
|
# purposes)
|
|
if cipher_mode in [
|
|
enums.BlockCipherMode.CBC,
|
|
enums.BlockCipherMode.ECB
|
|
]:
|
|
plain_text = self._handle_symmetric_padding(
|
|
self._symmetric_key_algorithms.get(decryption_algorithm),
|
|
plain_text,
|
|
padding_method,
|
|
undo_padding=True
|
|
)
|
|
|
|
return plain_text
|
|
|
|
def _create_rsa_key_pair(self, length, public_exponent=65537):
|
|
"""
|
|
Create an RSA key pair.
|
|
|
|
Args:
|
|
length(int): The length of the keys to be created. This value must
|
|
be compliant with the constraints of the provided algorithm.
|
|
public_exponent(int): The value of the public exponent needed to
|
|
generate the keys. Usually a small Fermat prime number.
|
|
Optional, defaults to 65537.
|
|
|
|
Returns:
|
|
dict: A dictionary containing the public key data, with the
|
|
following key/value fields:
|
|
* value - the bytes of the key
|
|
* format - a KeyFormatType enumeration for the bytes format
|
|
* public_exponent - the public exponent integer
|
|
dict: A dictionary containing the private key data, identical in
|
|
structure to the one above.
|
|
|
|
Raises:
|
|
CryptographicFailure: Raised when the key generation process
|
|
fails.
|
|
"""
|
|
self.logger.info(
|
|
"Generating an RSA key pair with length: {0}, and "
|
|
"public_exponent: {1}".format(
|
|
length, public_exponent
|
|
)
|
|
)
|
|
try:
|
|
private_key = rsa.generate_private_key(
|
|
public_exponent=public_exponent,
|
|
key_size=length,
|
|
backend=default_backend())
|
|
public_key = private_key.public_key()
|
|
|
|
private_bytes = private_key.private_bytes(
|
|
serialization.Encoding.DER,
|
|
serialization.PrivateFormat.PKCS8,
|
|
serialization.NoEncryption())
|
|
public_bytes = public_key.public_bytes(
|
|
serialization.Encoding.DER,
|
|
serialization.PublicFormat.PKCS1)
|
|
except Exception as e:
|
|
self.logger.exception(e)
|
|
raise exceptions.CryptographicFailure(
|
|
"An error occurred while generating the RSA key pair. "
|
|
"See the server log for more information."
|
|
)
|
|
|
|
public_key = {
|
|
'value': public_bytes,
|
|
'format': enums.KeyFormatType.PKCS_1,
|
|
'public_exponent': public_exponent
|
|
}
|
|
private_key = {
|
|
'value': private_bytes,
|
|
'format': enums.KeyFormatType.PKCS_8,
|
|
'public_exponent': public_exponent
|
|
}
|
|
|
|
return public_key, private_key
|
|
|
|
def derive_key(self,
|
|
derivation_method,
|
|
derivation_length,
|
|
derivation_data=None,
|
|
key_material=None,
|
|
hash_algorithm=None,
|
|
salt=None,
|
|
iteration_count=None,
|
|
encryption_algorithm=None,
|
|
cipher_mode=None,
|
|
padding_method=None,
|
|
iv_nonce=None):
|
|
"""
|
|
Derive key data using a variety of key derivation functions.
|
|
|
|
Args:
|
|
derivation_method (DerivationMethod): An enumeration specifying
|
|
the key derivation method to use. Required.
|
|
derivation_length (int): An integer specifying the size of the
|
|
derived key data in bytes. Required.
|
|
derivation_data (bytes): The non-cryptographic bytes to be used
|
|
in the key derivation process (e.g., the data to be encrypted,
|
|
hashed, HMACed). Required in the general case. Optional if the
|
|
derivation method is Hash and the key material is provided.
|
|
Optional, defaults to None.
|
|
key_material (bytes): The bytes of the key material to use for
|
|
key derivation. Required in the general case. Optional if
|
|
the derivation_method is HASH and derivation_data is provided.
|
|
Optional, defaults to None.
|
|
hash_algorithm (HashingAlgorithm): An enumeration specifying the
|
|
hashing algorithm to use with the key derivation method.
|
|
Required in the general case, optional if the derivation
|
|
method specifies encryption. Optional, defaults to None.
|
|
salt (bytes): Bytes representing a randomly generated salt.
|
|
Required if the derivation method is PBKDF2. Optional,
|
|
defaults to None.
|
|
iteration_count (int): An integer representing the number of
|
|
iterations to use when deriving key material. Required if
|
|
the derivation method is PBKDF2. Optional, defaults to None.
|
|
encryption_algorithm (CryptographicAlgorithm): An enumeration
|
|
specifying the symmetric encryption algorithm to use for
|
|
encryption-based key derivation. Required if the derivation
|
|
method specifies encryption. Optional, defaults to None.
|
|
cipher_mode (BlockCipherMode): An enumeration specifying the
|
|
block cipher mode to use with the encryption algorithm.
|
|
Required in in the general case if the derivation method
|
|
specifies encryption and the encryption algorithm is
|
|
specified. Optional if the encryption algorithm is RC4 (aka
|
|
ARC4). Optional, defaults to None.
|
|
padding_method (PaddingMethod): An enumeration specifying the
|
|
padding method to use on the data before encryption. Required
|
|
in in the general case if the derivation method specifies
|
|
encryption and the encryption algorithm is specified. Required
|
|
if the cipher mode is for block ciphers (e.g., CBC, ECB).
|
|
Optional otherwise, defaults to None.
|
|
iv_nonce (bytes): The IV/nonce value to use to initialize the mode
|
|
of the encryption algorithm. Required in the general case if
|
|
the derivation method specifies encryption and the encryption
|
|
algorithm is specified. Optional, defaults to None. If
|
|
required and not provided, it will be autogenerated.
|
|
|
|
Returns:
|
|
bytes: the bytes of the derived data
|
|
|
|
Raises:
|
|
InvalidField: Raised when cryptographic data and/or settings are
|
|
unsupported or incompatible with the derivation method.
|
|
|
|
Example:
|
|
>>> engine = CryptographyEngine()
|
|
>>> result = engine.derive_key(
|
|
... derivation_method=enums.DerivationMethod.HASH,
|
|
... derivation_length=16,
|
|
... derivation_data=b'abc',
|
|
... hash_algorithm=enums.HashingAlgorithm.MD5
|
|
... )
|
|
>>> result
|
|
b'\x90\x01P\x98<\xd2O\xb0\xd6\x96?}(\xe1\x7fr'
|
|
"""
|
|
if derivation_method == enums.DerivationMethod.ENCRYPT:
|
|
result = self.encrypt(
|
|
encryption_algorithm=encryption_algorithm,
|
|
encryption_key=key_material,
|
|
plain_text=derivation_data,
|
|
cipher_mode=cipher_mode,
|
|
padding_method=padding_method,
|
|
iv_nonce=iv_nonce
|
|
)
|
|
return result.get('cipher_text')
|
|
else:
|
|
# Handle key derivation functions that use hash algorithms
|
|
|
|
# Set up the hashing algorithm
|
|
if hash_algorithm is None:
|
|
raise exceptions.InvalidField("Hash algorithm is required.")
|
|
hashing_algorithm = self._encryption_hash_algorithms.get(
|
|
hash_algorithm,
|
|
None
|
|
)
|
|
if hashing_algorithm is None:
|
|
raise exceptions.InvalidField(
|
|
"Hash algorithm '{0}' is not a supported hashing "
|
|
"algorithm.".format(hash_algorithm)
|
|
)
|
|
|
|
if derivation_method == enums.DerivationMethod.HMAC:
|
|
df = hkdf.HKDF(
|
|
algorithm=hashing_algorithm(),
|
|
length=derivation_length,
|
|
salt=salt,
|
|
info=derivation_data,
|
|
backend=default_backend()
|
|
)
|
|
derived_data = df.derive(key_material)
|
|
return derived_data
|
|
elif derivation_method == enums.DerivationMethod.HASH:
|
|
if None not in [derivation_data, key_material]:
|
|
raise exceptions.InvalidField(
|
|
"For hash-based key derivation, specify only "
|
|
"derivation data or key material, not both."
|
|
)
|
|
elif derivation_data is not None:
|
|
hashing_data = derivation_data
|
|
elif key_material is not None:
|
|
hashing_data = key_material
|
|
else:
|
|
raise exceptions.InvalidField(
|
|
"For hash-based key derivation, derivation data or "
|
|
"key material must be specified."
|
|
)
|
|
|
|
df = hashes.Hash(
|
|
algorithm=hashing_algorithm(),
|
|
backend=default_backend()
|
|
)
|
|
df.update(hashing_data)
|
|
derived_data = df.finalize()
|
|
return derived_data
|
|
elif derivation_method == enums.DerivationMethod.PBKDF2:
|
|
if salt is None:
|
|
raise exceptions.InvalidField(
|
|
"For PBKDF2 key derivation, salt must be specified."
|
|
)
|
|
if iteration_count is None:
|
|
raise exceptions.InvalidField(
|
|
"For PBKDF2 key derivation, iteration count must be "
|
|
"specified."
|
|
)
|
|
|
|
df = pbkdf2.PBKDF2HMAC(
|
|
algorithm=hashing_algorithm(),
|
|
length=derivation_length,
|
|
salt=salt,
|
|
iterations=iteration_count,
|
|
backend=default_backend()
|
|
)
|
|
derived_data = df.derive(key_material)
|
|
return derived_data
|
|
elif derivation_method == enums.DerivationMethod.NIST800_108_C:
|
|
df = kbkdf.KBKDFHMAC(
|
|
algorithm=hashing_algorithm(),
|
|
mode=kbkdf.Mode.CounterMode,
|
|
length=derivation_length,
|
|
rlen=4,
|
|
llen=None,
|
|
location=kbkdf.CounterLocation.BeforeFixed,
|
|
label=None,
|
|
context=None,
|
|
fixed=derivation_data,
|
|
backend=default_backend()
|
|
)
|
|
derived_data = df.derive(key_material)
|
|
return derived_data
|
|
else:
|
|
raise exceptions.InvalidField(
|
|
"Derivation method '{0}' is not a supported key "
|
|
"derivation method.".format(derivation_method)
|
|
)
|
|
|
|
def wrap_key(self,
|
|
key_material,
|
|
wrapping_method,
|
|
key_wrap_algorithm,
|
|
encryption_key):
|
|
"""
|
|
Args:
|
|
key_material (bytes): The bytes of the key to wrap. Required.
|
|
wrapping_method (WrappingMethod): A WrappingMethod enumeration
|
|
specifying what wrapping technique to use to wrap the key
|
|
material. Required.
|
|
key_wrap_algorithm (BlockCipherMode): A BlockCipherMode
|
|
enumeration specifying the key wrapping algorithm to use to
|
|
wrap the key material. Required.
|
|
encryption_key (bytes): The bytes of the encryption key to use
|
|
to encrypt the key material. Required.
|
|
|
|
Returns:
|
|
bytes: the bytes of the wrapped key
|
|
|
|
Raises:
|
|
CryptographicFailure: Raised when an error occurs during key
|
|
wrapping.
|
|
InvalidField: Raised when an unsupported wrapping or encryption
|
|
algorithm is specified.
|
|
|
|
Example:
|
|
>>> engine = CryptographyEngine()
|
|
>>> result = engine.wrap_key(
|
|
... key_material=(
|
|
... b'\x00\x11\x22\x33\x44\x55\x66\x77'
|
|
... b'\x88\x99\xAA\xBB\xCC\xDD\xEE\xFF'
|
|
... )
|
|
... wrapping_method=enums.WrappingMethod.ENCRYPT,
|
|
... key_wrap_algorithm=enums.BlockCipherMode.NIST_KEY_WRAP,
|
|
... encryption_key=(
|
|
... b'\x00\x01\x02\x03\x04\x05\x06\x07'
|
|
... b'\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F'
|
|
... )
|
|
... )
|
|
>>> result
|
|
b'\x1f\xa6\x8b\n\x81\x12\xb4G\xae\xf3K\xd8\xfbZ{\x82\x9d>\x86#q
|
|
\xd2\xcf\xe5'
|
|
"""
|
|
if wrapping_method == enums.WrappingMethod.ENCRYPT:
|
|
if key_wrap_algorithm == enums.BlockCipherMode.NIST_KEY_WRAP:
|
|
try:
|
|
wrapped_key = keywrap.aes_key_wrap(
|
|
encryption_key,
|
|
key_material,
|
|
default_backend()
|
|
)
|
|
return wrapped_key
|
|
except Exception as e:
|
|
raise exceptions.CryptographicFailure(str(e))
|
|
else:
|
|
raise exceptions.InvalidField(
|
|
"Encryption algorithm '{0}' is not a supported key "
|
|
"wrapping algorithm.".format(key_wrap_algorithm)
|
|
)
|
|
else:
|
|
raise exceptions.InvalidField(
|
|
"Wrapping method '{0}' is not a supported key wrapping "
|
|
"method.".format(wrapping_method)
|
|
)
|