80 lines
2.9 KiB
Python
80 lines
2.9 KiB
Python
# -*- coding: utf-8 -*-
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#
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# Copyright (c) 2019, Felix Fontein <felix@fontein.de>
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# GNU General Public License v3.0+ (see LICENSES/GPL-3.0-or-later.txt or https://www.gnu.org/licenses/gpl-3.0.txt)
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# SPDX-License-Identifier: GPL-3.0-or-later
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from __future__ import absolute_import, division, print_function
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__metaclass__ = type
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PEM_START = '-----BEGIN '
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PEM_END = '-----'
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PKCS8_PRIVATEKEY_NAMES = ('PRIVATE KEY', 'ENCRYPTED PRIVATE KEY')
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PKCS1_PRIVATEKEY_SUFFIX = ' PRIVATE KEY'
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def identify_pem_format(content, encoding='utf-8'):
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'''Given the contents of a binary file, tests whether this could be a PEM file.'''
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try:
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first_pem = extract_first_pem(content.decode(encoding))
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if first_pem is None:
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return False
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lines = first_pem.splitlines(False)
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if lines[0].startswith(PEM_START) and lines[0].endswith(PEM_END) and len(lines[0]) > len(PEM_START) + len(PEM_END):
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return True
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except UnicodeDecodeError:
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pass
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return False
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def identify_private_key_format(content, encoding='utf-8'):
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'''Given the contents of a private key file, identifies its format.'''
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# See https://github.com/openssl/openssl/blob/master/crypto/pem/pem_pkey.c#L40-L85
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# (PEM_read_bio_PrivateKey)
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# and https://github.com/openssl/openssl/blob/master/include/openssl/pem.h#L46-L47
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# (PEM_STRING_PKCS8, PEM_STRING_PKCS8INF)
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try:
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first_pem = extract_first_pem(content.decode(encoding))
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if first_pem is None:
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return 'raw'
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lines = first_pem.splitlines(False)
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if lines[0].startswith(PEM_START) and lines[0].endswith(PEM_END) and len(lines[0]) > len(PEM_START) + len(PEM_END):
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name = lines[0][len(PEM_START):-len(PEM_END)]
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if name in PKCS8_PRIVATEKEY_NAMES:
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return 'pkcs8'
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if len(name) > len(PKCS1_PRIVATEKEY_SUFFIX) and name.endswith(PKCS1_PRIVATEKEY_SUFFIX):
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return 'pkcs1'
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return 'unknown-pem'
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except UnicodeDecodeError:
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pass
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return 'raw'
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def split_pem_list(text, keep_inbetween=False):
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'''
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Split concatenated PEM objects into a list of strings, where each is one PEM object.
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'''
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result = []
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current = [] if keep_inbetween else None
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for line in text.splitlines(True):
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if line.strip():
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if not keep_inbetween and line.startswith('-----BEGIN '):
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current = []
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if current is not None:
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current.append(line)
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if line.startswith('-----END '):
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result.append(''.join(current))
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current = [] if keep_inbetween else None
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return result
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def extract_first_pem(text):
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'''
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Given one PEM or multiple concatenated PEM objects, return only the first one, or None if there is none.
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'''
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all_pems = split_pem_list(text)
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if not all_pems:
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return None
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return all_pems[0]
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