72 lines
2.6 KiB
Python
72 lines
2.6 KiB
Python
# 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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from cryptography.hazmat.backends import default_backend
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from cryptography.hazmat.primitives.asymmetric import padding
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from cryptography.hazmat.primitives.asymmetric import utils
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from cryptography.hazmat.primitives import hashes
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from cryptography.hazmat.primitives import serialization
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from openstack import exceptions
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from openstack.image.iterable_chunked_file import IterableChunkedFile
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HASH_METHODS = {
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'SHA-224': hashes.SHA224(),
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'SHA-256': hashes.SHA256(),
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'SHA-384': hashes.SHA384(),
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'SHA-512': hashes.SHA512(),
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}
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class ImageSigner:
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"""Image file signature generator.
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Generates signatures for files using a specified private key file.
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"""
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def __init__(self, hash_method='SHA-256', padding_method='RSA-PSS'):
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padding_types = {
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'RSA-PSS': padding.PSS(
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mgf=padding.MGF1(HASH_METHODS[hash_method]),
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salt_length=padding.PSS.MAX_LENGTH,
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)
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}
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# informational attributes
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self.hash_method = hash_method
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self.padding_method = padding_method
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# runtime objects
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self.private_key = None
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self.hash = HASH_METHODS[hash_method]
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self.hasher = hashes.Hash(self.hash, default_backend())
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self.padding = padding_types[padding_method]
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def load_private_key(self, file_path, password=None):
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with open(file_path, 'rb') as key_file:
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self.private_key = serialization.load_pem_private_key(
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key_file.read(), password=password, backend=default_backend()
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)
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def generate_signature(self, file_obj):
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if not self.private_key:
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raise exceptions.SDKException("private_key not set")
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file_obj.seek(0)
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chunked_file = IterableChunkedFile(file_obj)
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for chunk in chunked_file:
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self.hasher.update(chunk)
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file_obj.seek(0)
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digest = self.hasher.finalize()
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signature = self.private_key.sign(
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digest, self.padding, utils.Prehashed(self.hash)
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)
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return signature
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