116 lines
4.6 KiB
Python
116 lines
4.6 KiB
Python
# -*- coding: utf-8 -*- #
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# Copyright 2020 Google LLC. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain 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,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Key generation utilities."""
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from __future__ import absolute_import
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from __future__ import division
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from __future__ import unicode_literals
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import os
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import sys
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from googlecloudsdk.command_lib.privateca import exceptions
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from googlecloudsdk.core import log
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from googlecloudsdk.core.util import files
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KEY_OUTPUT_WARNING = """A private key was exported to {}.
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Possession of this key file could allow anybody to act as this certificate's
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subject. Please make sure that you store this key file in a secure location at
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all times, and ensure that only authorized users have access to it.
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"""
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def RSAKeyGen(key_size=2048):
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"""Generates an RSA public-private key pair.
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Args:
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key_size: The size of the RSA key, in number of bytes. Defaults to 2048.
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Returns:
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A tuple with: (private_key, public_key) both serialized in PKCS1 as bytes.
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"""
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import_error_msg = ('Cannot load the Pyca cryptography library. Either the '
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'library is not installed, or site packages are not '
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'enabled for the Google Cloud SDK. Please consult Cloud '
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'KMS documentation on adding Pyca to Google Cloud SDK '
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'for further instructions.\n'
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'https://cloud.google.com/kms/docs/crypto')
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try:
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# TODO(b/141249289): Move imports to the top of the file. In the
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# meantime, until we're sure that all Private CA SDK users have the
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# cryptography module available, let's not error out if we can't load the
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# module unless we're actually going down this code path.
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# pylint: disable=g-import-not-at-top
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from cryptography.hazmat.primitives.asymmetric import rsa
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from cryptography.hazmat.backends.openssl.backend import backend
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except ImportError:
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log.err.Print(import_error_msg)
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sys.exit(1)
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# The serialization modules have moved in cryptography version 3.4 and above.
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# Try both the old and new locations to support both versions. See b/183521338
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# for more context.
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try:
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# pylint: disable=g-import-not-at-top
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from cryptography.hazmat.primitives.serialization.base import Encoding
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from cryptography.hazmat.primitives.serialization.base import PrivateFormat
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from cryptography.hazmat.primitives.serialization.base import PublicFormat
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from cryptography.hazmat.primitives.serialization.base import NoEncryption
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except ImportError:
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try:
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# pylint: disable=g-import-not-at-top
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from cryptography.hazmat.primitives.serialization import Encoding
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from cryptography.hazmat.primitives.serialization import PrivateFormat
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from cryptography.hazmat.primitives.serialization import PublicFormat
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from cryptography.hazmat.primitives.serialization import NoEncryption
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except ImportError:
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log.err.Print(import_error_msg)
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sys.exit(1)
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private_key = rsa.generate_private_key(
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public_exponent=65537, key_size=key_size, backend=backend)
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private_key_bytes = private_key.private_bytes(
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Encoding.PEM,
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PrivateFormat.TraditionalOpenSSL, # PKCS#1
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NoEncryption())
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public_key_bytes = private_key.public_key().public_bytes(
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Encoding.PEM, PublicFormat.SubjectPublicKeyInfo)
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return private_key_bytes, public_key_bytes
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def ExportPrivateKey(private_key_output_file, private_key_bytes):
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"""Export a private key to a filename, printing a warning to the user.
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Args:
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private_key_output_file: The path of the file to export to.
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private_key_bytes: The content in byte format to export.
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"""
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try:
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# Make sure this file is only accesible to the running user before writing.
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files.PrivatizeFile(private_key_output_file)
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files.WriteFileContents(private_key_output_file, private_key_bytes)
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# Make file readable only by owner.
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os.chmod(private_key_output_file, 0o400)
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log.warning(KEY_OUTPUT_WARNING.format(private_key_output_file))
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except (files.Error, OSError, IOError):
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raise exceptions.FileOutputError(
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"Error writing to private key output file named '{}'".format(
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private_key_output_file))
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