mirror of
https://github.com/ansible-collections/community.crypto.git
synced 2026-05-06 21:33:00 +00:00
New module utils openssh.certificate (#246)
* Initial commit * Adding informational comments * Adding changelog fragment * Fixing CRLF changelog fragment * Refactoring public number parsing and added chaining for writer methods * Adding more descriptive error for invalid certificate data * Fixing signature data parsing * Correcting ed25519 signature type to binary * Applying initial review suggestions and fixing option-list writer * Applying review suggestions * Making OpensshWriter private
This commit is contained in:
Ajpantuso
GitHub
337
plugins/module_utils/openssh/certificate.py
Normal file
337
plugins/module_utils/openssh/certificate.py
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@@ -0,0 +1,337 @@
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# -*- coding: utf-8 -*-
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#
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# Copyright: (c) 2021, Andrew Pantuso (@ajpantuso) <ajpantuso@gmail.com>
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#
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# Ansible is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
|
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# Ansible is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with Ansible. If not, see <http://www.gnu.org/licenses/>.
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from __future__ import absolute_import, division, print_function
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__metaclass__ = type
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# Protocol References
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# -------------------
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# https://datatracker.ietf.org/doc/html/rfc4251
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# https://datatracker.ietf.org/doc/html/rfc4253
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# https://datatracker.ietf.org/doc/html/rfc5656
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# https://datatracker.ietf.org/doc/html/rfc8032
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# https://cvsweb.openbsd.org/src/usr.bin/ssh/PROTOCOL.certkeys?annotate=HEAD
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#
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# Inspired by:
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# ------------
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# https://github.com/pyca/cryptography/blob/main/src/cryptography/hazmat/primitives/serialization/ssh.py
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# https://github.com/paramiko/paramiko/blob/master/paramiko/message.py
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import abc
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import binascii
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import os
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from base64 import b64encode
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from hashlib import sha256
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from ansible.module_utils import six
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from ansible_collections.community.crypto.plugins.module_utils.openssh.utils import (
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OpensshParser,
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_OpensshWriter,
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)
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# See https://cvsweb.openbsd.org/src/usr.bin/ssh/PROTOCOL.certkeys?annotate=HEAD
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_USER_TYPE = 1
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_HOST_TYPE = 2
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_SSH_TYPE_STRINGS = {
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'rsa': b"ssh-rsa",
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'dsa': b"ssh-dss",
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'ecdsa-nistp256': b"ecdsa-sha2-nistp256",
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'ecdsa-nistp384': b"ecdsa-sha2-nistp384",
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'ecdsa-nistp521': b"ecdsa-sha2-nistp521",
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'ed25519': b"ssh-ed25519",
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}
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_CERT_SUFFIX_V01 = b"-cert-v01@openssh.com"
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# See https://datatracker.ietf.org/doc/html/rfc5656#section-6.1
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_ECDSA_CURVE_IDENTIFIERS = {
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'ecdsa-nistp256': b'nistp256',
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'ecdsa-nistp384': b'nistp384',
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'ecdsa-nistp521': b'nistp521',
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}
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_ECDSA_CURVE_IDENTIFIERS_LOOKUP = {
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b'nistp256': 'ecdsa-nistp256',
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b'nistp384': 'ecdsa-nistp384',
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b'nistp521': 'ecdsa-nistp521',
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}
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@six.add_metaclass(abc.ABCMeta)
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class OpensshCertificateInfo:
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"""Encapsulates all certificate information which is signed by a CA key"""
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def __init__(self,
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nonce=None,
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serial=None,
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cert_type=None,
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key_id=None,
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principals=None,
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valid_after=None,
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valid_before=None,
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critical_options=None,
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extensions=None,
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reserved=None):
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self.nonce = nonce
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self.serial = serial
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self._cert_type = cert_type
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self.key_id = key_id
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self.principals = principals
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self.valid_after = valid_after
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self.valid_before = valid_before
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self.critical_options = critical_options
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self.extensions = extensions
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self.reserved = reserved
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self.type_string = None
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@property
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def cert_type(self):
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if self._cert_type == _USER_TYPE:
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return 'user'
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elif self._cert_type == _HOST_TYPE:
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return 'host'
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else:
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return ''
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@cert_type.setter
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def cert_type(self, cert_type):
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if cert_type == 'user' or cert_type == _USER_TYPE:
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self._cert_type = _USER_TYPE
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elif cert_type == 'host' or cert_type == _HOST_TYPE:
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self._cert_type = _HOST_TYPE
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else:
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raise ValueError("%s is not a valid certificate type" % cert_type)
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@abc.abstractmethod
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def public_key_fingerprint(self):
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pass
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@abc.abstractmethod
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def parse_public_numbers(self, parser):
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pass
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class OpensshRSACertificateInfo(OpensshCertificateInfo):
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def __init__(self, e=None, n=None, **kwargs):
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super(OpensshRSACertificateInfo, self).__init__(**kwargs)
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self.type_string = _SSH_TYPE_STRINGS['rsa'] + _CERT_SUFFIX_V01
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self.e = e
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self.n = n
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# See https://datatracker.ietf.org/doc/html/rfc4253#section-6.6
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def public_key_fingerprint(self):
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if any([self.e is None, self.n is None]):
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return b''
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writer = _OpensshWriter()
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writer.string(_SSH_TYPE_STRINGS['rsa'])
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writer.mpint(self.e)
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writer.mpint(self.n)
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return fingerprint(writer.bytes())
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def parse_public_numbers(self, parser):
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self.e = parser.mpint()
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self.n = parser.mpint()
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class OpensshDSACertificateInfo(OpensshCertificateInfo):
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def __init__(self, p=None, q=None, g=None, y=None, **kwargs):
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super(OpensshDSACertificateInfo, self).__init__(**kwargs)
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self.type_string = _SSH_TYPE_STRINGS['dsa'] + _CERT_SUFFIX_V01
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self.p = p
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self.q = q
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self.g = g
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self.y = y
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# See https://datatracker.ietf.org/doc/html/rfc4253#section-6.6
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def public_key_fingerprint(self):
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if any([self.p is None, self.q is None, self.g is None, self.y is None]):
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return b''
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writer = _OpensshWriter()
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writer.string(_SSH_TYPE_STRINGS['dsa'])
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writer.mpint(self.p)
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writer.mpint(self.q)
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writer.mpint(self.g)
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writer.mpint(self.y)
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return fingerprint(writer.bytes())
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def parse_public_numbers(self, parser):
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self.p = parser.mpint()
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self.q = parser.mpint()
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self.g = parser.mpint()
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self.y = parser.mpint()
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class OpensshECDSACertificateInfo(OpensshCertificateInfo):
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def __init__(self, curve=None, public_key=None, **kwargs):
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super(OpensshECDSACertificateInfo, self).__init__(**kwargs)
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self._curve = None
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if curve is not None:
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self.curve = curve
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self.public_key = public_key
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@property
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def curve(self):
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return self._curve
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@curve.setter
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def curve(self, curve):
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if curve in _ECDSA_CURVE_IDENTIFIERS.values():
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self._curve = curve
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self.type_string = _SSH_TYPE_STRINGS[_ECDSA_CURVE_IDENTIFIERS_LOOKUP[curve]] + _CERT_SUFFIX_V01
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else:
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raise ValueError(
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"Curve must be one of %s" % (b','.join(list(_ECDSA_CURVE_IDENTIFIERS.values()))).decode('UTF-8')
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)
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# See https://datatracker.ietf.org/doc/html/rfc4253#section-6.6
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def public_key_fingerprint(self):
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if any([self.curve is None, self.public_key is None]):
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return b''
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writer = _OpensshWriter()
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writer.string(_SSH_TYPE_STRINGS[_ECDSA_CURVE_IDENTIFIERS_LOOKUP[self.curve]])
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writer.string(self.curve)
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writer.string(self.public_key)
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return fingerprint(writer.bytes())
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def parse_public_numbers(self, parser):
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self.curve = parser.string()
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self.public_key = parser.string()
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class OpensshED25519CertificateInfo(OpensshCertificateInfo):
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def __init__(self, pk=None, **kwargs):
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super(OpensshED25519CertificateInfo, self).__init__(**kwargs)
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self.type_string = _SSH_TYPE_STRINGS['ed25519'] + _CERT_SUFFIX_V01
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self.pk = pk
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def public_key_fingerprint(self):
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if self.pk is None:
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return b''
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writer = _OpensshWriter()
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writer.string(_SSH_TYPE_STRINGS['ed25519'])
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writer.string(self.pk)
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return fingerprint(writer.bytes())
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def parse_public_numbers(self, parser):
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self.pk = parser.string()
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# See https://cvsweb.openbsd.org/src/usr.bin/ssh/PROTOCOL.certkeys?annotate=HEAD
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class OpensshCertificate(object):
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"""Encapsulates a formatted OpenSSH certificate including signature and signing key"""
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def __init__(self, cert_info, signing_key, signature):
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self.cert_info = cert_info
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self.signing_key = signing_key
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self.signature = signature
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@classmethod
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def load(cls, path):
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if not os.path.exists(path):
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raise ValueError("%s is not a valid path." % path)
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try:
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with open(path, 'rb') as cert_file:
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data = cert_file.read()
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except (IOError, OSError) as e:
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raise ValueError("%s cannot be opened for reading: %s" % (path, e))
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try:
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format_identifier, b64_cert = data.split(b' ')[:2]
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cert = binascii.a2b_base64(b64_cert)
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except (binascii.Error, ValueError):
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raise ValueError("Certificate not in OpenSSH format")
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for key_type, string in _SSH_TYPE_STRINGS.items():
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if format_identifier == string + _CERT_SUFFIX_V01:
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pub_key_type = key_type
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break
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else:
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raise ValueError("Invalid certificate format identifier: %s" % format_identifier)
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parser = OpensshParser(cert)
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if format_identifier != parser.string():
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raise ValueError("Certificate formats do not match")
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try:
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cert_info = cls._parse_cert_info(pub_key_type, parser)
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signing_key = parser.string()
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signature = parser.string()
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except (TypeError, ValueError) as e:
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raise ValueError("Invalid certificate data: %s" % e)
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if parser.remaining_bytes():
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raise ValueError(
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"%s bytes of additional data was not parsed while loading %s" % (parser.remaining_bytes(), path)
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)
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return cls(
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cert_info=cert_info,
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signing_key=signing_key,
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signature=signature,
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)
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def signing_key_fingerprint(self):
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return fingerprint(self.signing_key)
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@staticmethod
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def _parse_cert_info(pub_key_type, parser):
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cert_info = get_cert_info_object(pub_key_type)
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cert_info.nonce = parser.string()
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cert_info.parse_public_numbers(parser)
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cert_info.serial = parser.uint64()
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cert_info.cert_type = parser.uint32()
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cert_info.key_id = parser.string()
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cert_info.principals = parser.string_list()
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cert_info.valid_after = parser.uint64()
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cert_info.valid_before = parser.uint64()
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cert_info.critical_options = parser.option_list()
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cert_info.extensions = parser.option_list()
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cert_info.reserved = parser.string()
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return cert_info
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def fingerprint(public_key):
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"""Generates a SHA256 hash and formats output to resemble ``ssh-keygen``"""
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h = sha256()
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h.update(public_key)
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return b'SHA256:' + b64encode(h.digest()).rstrip(b'=')
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def get_cert_info_object(key_type):
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if key_type == 'rsa':
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cert_info = OpensshRSACertificateInfo()
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elif key_type == 'dsa':
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cert_info = OpensshDSACertificateInfo()
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elif key_type in ('ecdsa-nistp256', 'ecdsa-nistp384', 'ecdsa-nistp521'):
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cert_info = OpensshECDSACertificateInfo()
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elif key_type == 'ed25519':
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cert_info = OpensshED25519CertificateInfo()
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else:
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raise ValueError("%s is not a valid key type" % key_type)
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return cert_info
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@@ -1,6 +1,7 @@
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# -*- coding: utf-8 -*-
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#
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# (c) 2020, Doug Stanley <doug+ansible@technologixllc.com>
|
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# Copyright: (c) 2020, Doug Stanley <doug+ansible@technologixllc.com>
|
||||
# Copyright: (c) 2021, Andrew Pantuso (@ajpantuso) <ajpantuso@gmail.com>
|
||||
#
|
||||
# Ansible is free software: you can redistribute it and/or modify
|
||||
# it under the terms of the GNU General Public License as published by
|
||||
@@ -19,6 +20,38 @@ from __future__ import absolute_import, division, print_function
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__metaclass__ = type
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import re
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from struct import Struct
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from ansible.module_utils.six import PY3
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# Protocol References
|
||||
# -------------------
|
||||
# https://datatracker.ietf.org/doc/html/rfc4251
|
||||
# https://datatracker.ietf.org/doc/html/rfc4253
|
||||
# https://datatracker.ietf.org/doc/html/rfc5656
|
||||
# https://datatracker.ietf.org/doc/html/rfc8032
|
||||
#
|
||||
# Inspired by:
|
||||
# ------------
|
||||
# https://github.com/pyca/cryptography/blob/main/src/cryptography/hazmat/primitives/serialization/ssh.py
|
||||
# https://github.com/paramiko/paramiko/blob/master/paramiko/message.py
|
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if PY3:
|
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long = int
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# 0 (False) or 1 (True) encoded as a single byte
|
||||
_BOOLEAN = Struct(b'?')
|
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# Unsigned 8-bit integer in network-byte-order
|
||||
_UBYTE = Struct(b'!B')
|
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_UBYTE_MAX = 0xFF
|
||||
# Unsigned 32-bit integer in network-byte-order
|
||||
_UINT32 = Struct(b'!I')
|
||||
# Unsigned 32-bit little endian integer
|
||||
_UINT32_LE = Struct(b'<I')
|
||||
_UINT32_MAX = 0xFFFFFFFF
|
||||
# Unsigned 64-bit integer in network-byte-order
|
||||
_UINT64 = Struct(b'!Q')
|
||||
_UINT64_MAX = 0xFFFFFFFFFFFFFFFF
|
||||
|
||||
|
||||
def parse_openssh_version(version_string):
|
||||
@@ -33,3 +66,311 @@ def parse_openssh_version(version_string):
|
||||
version = None
|
||||
|
||||
return version
|
||||
|
||||
|
||||
# See https://datatracker.ietf.org/doc/html/rfc4251#section-5 for SSH data types
|
||||
class OpensshParser(object):
|
||||
"""Parser for OpenSSH encoded objects"""
|
||||
BOOLEAN_OFFSET = 1
|
||||
UINT32_OFFSET = 4
|
||||
UINT64_OFFSET = 8
|
||||
|
||||
def __init__(self, data):
|
||||
if not isinstance(data, (bytes, bytearray)):
|
||||
raise TypeError("Data must be bytes-like not %s" % type(data))
|
||||
|
||||
self._data = memoryview(data) if PY3 else data
|
||||
self._pos = 0
|
||||
|
||||
def boolean(self):
|
||||
next_pos = self._check_position(self.BOOLEAN_OFFSET)
|
||||
|
||||
value = _BOOLEAN.unpack(self._data[self._pos:next_pos])[0]
|
||||
self._pos = next_pos
|
||||
return value
|
||||
|
||||
def uint32(self):
|
||||
next_pos = self._check_position(self.UINT32_OFFSET)
|
||||
|
||||
value = _UINT32.unpack(self._data[self._pos:next_pos])[0]
|
||||
self._pos = next_pos
|
||||
return value
|
||||
|
||||
def uint64(self):
|
||||
next_pos = self._check_position(self.UINT64_OFFSET)
|
||||
|
||||
value = _UINT64.unpack(self._data[self._pos:next_pos])[0]
|
||||
self._pos = next_pos
|
||||
return value
|
||||
|
||||
def string(self):
|
||||
length = self.uint32()
|
||||
|
||||
next_pos = self._check_position(length)
|
||||
|
||||
value = self._data[self._pos:next_pos]
|
||||
self._pos = next_pos
|
||||
# Cast to bytes is required as a memoryview slice is itself a memoryview
|
||||
return value if not PY3 else bytes(value)
|
||||
|
||||
def mpint(self):
|
||||
return self._big_int(self.string(), "big", signed=True)
|
||||
|
||||
def name_list(self):
|
||||
raw_string = self.string()
|
||||
return raw_string.decode('ASCII').split(',')
|
||||
|
||||
# Convenience function, but not an official data type from SSH
|
||||
def string_list(self):
|
||||
result = []
|
||||
raw_string = self.string()
|
||||
|
||||
if raw_string:
|
||||
parser = OpensshParser(raw_string)
|
||||
while parser.remaining_bytes():
|
||||
result.append(parser.string())
|
||||
|
||||
return result
|
||||
|
||||
# Convenience function, but not an official data type from SSH
|
||||
def option_list(self):
|
||||
result = []
|
||||
raw_string = self.string()
|
||||
|
||||
if raw_string:
|
||||
parser = OpensshParser(raw_string)
|
||||
|
||||
while parser.remaining_bytes():
|
||||
name = parser.string()
|
||||
data = parser.string()
|
||||
if data:
|
||||
# data is doubly-encoded
|
||||
data = OpensshParser(data).string()
|
||||
result.append((name, data))
|
||||
|
||||
return result
|
||||
|
||||
def seek(self, offset):
|
||||
self._pos = self._check_position(offset)
|
||||
|
||||
return self._pos
|
||||
|
||||
def remaining_bytes(self):
|
||||
return len(self._data) - self._pos
|
||||
|
||||
def _check_position(self, offset):
|
||||
if self._pos + offset > len(self._data):
|
||||
raise ValueError("Insufficient data remaining at position: %s" % self._pos)
|
||||
elif self._pos + offset < 0:
|
||||
raise ValueError("Position cannot be less than zero.")
|
||||
else:
|
||||
return self._pos + offset
|
||||
|
||||
@classmethod
|
||||
def signature_data(cls, signature_string):
|
||||
signature_data = {}
|
||||
|
||||
parser = cls(signature_string)
|
||||
signature_type = parser.string()
|
||||
signature_blob = parser.string()
|
||||
|
||||
blob_parser = cls(signature_blob)
|
||||
if signature_type == b'ssh-rsa':
|
||||
# https://datatracker.ietf.org/doc/html/rfc4253#section-6.6
|
||||
signature_data['s'] = cls._big_int(signature_blob, "big")
|
||||
elif signature_type == b'ssh-dss':
|
||||
# https://datatracker.ietf.org/doc/html/rfc4253#section-6.6
|
||||
signature_data['r'] = cls._big_int(signature_blob[:20], "big")
|
||||
signature_data['s'] = cls._big_int(signature_blob[20:], "big")
|
||||
elif signature_type in (b'ecdsa-sha2-nistp256', b'ecdsa-sha2-nistp384', b'ecdsa-sha2-nistp521'):
|
||||
# https://datatracker.ietf.org/doc/html/rfc5656#section-3.1.2
|
||||
signature_data['r'] = blob_parser.mpint()
|
||||
signature_data['s'] = blob_parser.mpint()
|
||||
elif signature_type == b'ssh-ed25519':
|
||||
# https://datatracker.ietf.org/doc/html/rfc8032#section-5.1.2
|
||||
signature_data['R'] = cls._big_int(signature_blob[:32], "little")
|
||||
signature_data['S'] = cls._big_int(signature_blob[32:], "little")
|
||||
else:
|
||||
raise ValueError("%s is not a valid signature type" % signature_type)
|
||||
|
||||
signature_data['signature_type'] = signature_type
|
||||
|
||||
return signature_data
|
||||
|
||||
@classmethod
|
||||
def _big_int(cls, raw_string, byte_order, signed=False):
|
||||
if byte_order not in ("big", "little"):
|
||||
raise ValueError("Byte_order must be one of (big, little) not %s" % byte_order)
|
||||
|
||||
if PY3:
|
||||
return int.from_bytes(raw_string, byte_order, signed=signed)
|
||||
|
||||
result = 0
|
||||
byte_length = len(raw_string)
|
||||
|
||||
if byte_length > 0:
|
||||
# Check sign-bit
|
||||
msb = raw_string[0] if byte_order == "big" else raw_string[-1]
|
||||
negative = bool(ord(msb) & 0x80)
|
||||
# Match pad value for two's complement
|
||||
pad = b'\xFF' if signed and negative else b'\x00'
|
||||
# The definition of ``mpint`` enforces that unnecessary bytes are not encoded so they are added back
|
||||
pad_length = (4 - byte_length % 4)
|
||||
if pad_length < 4:
|
||||
raw_string = pad * pad_length + raw_string if byte_order == "big" else raw_string + pad * pad_length
|
||||
byte_length += pad_length
|
||||
# Accumulate arbitrary precision integer bytes in the appropriate order
|
||||
if byte_order == "big":
|
||||
for i in range(0, byte_length, cls.UINT32_OFFSET):
|
||||
left_shift = result << cls.UINT32_OFFSET * 8
|
||||
result = left_shift + _UINT32.unpack(raw_string[i:i + cls.UINT32_OFFSET])[0]
|
||||
else:
|
||||
for i in range(byte_length, 0, -cls.UINT32_OFFSET):
|
||||
left_shift = result << cls.UINT32_OFFSET * 8
|
||||
result = left_shift + _UINT32_LE.unpack(raw_string[i - cls.UINT32_OFFSET:i])[0]
|
||||
# Adjust for two's complement
|
||||
if signed and negative:
|
||||
result -= 1 << (8 * byte_length)
|
||||
|
||||
return result
|
||||
|
||||
|
||||
class _OpensshWriter(object):
|
||||
"""Writes SSH encoded values to a bytes-like buffer
|
||||
|
||||
.. warning::
|
||||
This class is a private API and must not be exported outside of the openssh module_utils.
|
||||
It is not to be used to construct Openssh objects, but rather as a utility to assist
|
||||
in validating parsed material.
|
||||
"""
|
||||
def __init__(self, buffer=None):
|
||||
if buffer is not None:
|
||||
if not isinstance(buffer, (bytes, bytearray)):
|
||||
raise TypeError("Buffer must be a bytes-like object not %s" % type(buffer))
|
||||
else:
|
||||
buffer = bytearray()
|
||||
|
||||
self._buff = buffer
|
||||
|
||||
def boolean(self, value):
|
||||
if not isinstance(value, bool):
|
||||
raise TypeError("Value must be of type bool not %s" % type(value))
|
||||
|
||||
self._buff.extend(_BOOLEAN.pack(value))
|
||||
|
||||
return self
|
||||
|
||||
def uint32(self, value):
|
||||
if not isinstance(value, int):
|
||||
raise TypeError("Value must be of type int not %s" % type(value))
|
||||
if value < 0 or value > _UINT32_MAX:
|
||||
raise ValueError("Value must be a positive integer less than %s" % _UINT32_MAX)
|
||||
|
||||
self._buff.extend(_UINT32.pack(value))
|
||||
|
||||
return self
|
||||
|
||||
def uint64(self, value):
|
||||
if not isinstance(value, (long, int)):
|
||||
raise TypeError("Value must be of type (long, int) not %s" % type(value))
|
||||
if value < 0 or value > _UINT64_MAX:
|
||||
raise ValueError("Value must be a positive integer less than %s" % _UINT64_MAX)
|
||||
|
||||
self._buff.extend(_UINT64.pack(value))
|
||||
|
||||
return self
|
||||
|
||||
def string(self, value):
|
||||
if not isinstance(value, (bytes, bytearray)):
|
||||
raise TypeError("Value must be bytes-like not %s" % type(value))
|
||||
self.uint32(len(value))
|
||||
self._buff.extend(value)
|
||||
|
||||
return self
|
||||
|
||||
def mpint(self, value):
|
||||
if not isinstance(value, (int, long)):
|
||||
raise TypeError("Value must be of type (long, int) not %s" % type(value))
|
||||
|
||||
self.string(self._int_to_mpint(value))
|
||||
|
||||
return self
|
||||
|
||||
def name_list(self, value):
|
||||
if not isinstance(value, list):
|
||||
raise TypeError("Value must be a list of byte strings not %s" % type(value))
|
||||
|
||||
try:
|
||||
self.string(','.join(value).encode('ASCII'))
|
||||
except UnicodeEncodeError as e:
|
||||
raise ValueError("Name-list's must consist of US-ASCII characters: %s" % e)
|
||||
|
||||
return self
|
||||
|
||||
def string_list(self, value):
|
||||
if not isinstance(value, list):
|
||||
raise TypeError("Value must be a list of byte string not %s" % type(value))
|
||||
|
||||
writer = _OpensshWriter()
|
||||
for s in value:
|
||||
writer.string(s)
|
||||
|
||||
self.string(writer.bytes())
|
||||
|
||||
return self
|
||||
|
||||
def option_list(self, value):
|
||||
if not isinstance(value, list) or (value and not isinstance(value[0], tuple)):
|
||||
raise TypeError("Value must be a list of tuples")
|
||||
|
||||
writer = _OpensshWriter()
|
||||
for name, data in value:
|
||||
writer.string(name)
|
||||
# SSH option data is encoded twice though this behavior is not documented
|
||||
writer.string(_OpensshWriter().string(data).bytes() if data else bytes())
|
||||
|
||||
self.string(writer.bytes())
|
||||
|
||||
return self
|
||||
|
||||
@staticmethod
|
||||
def _int_to_mpint(num):
|
||||
if PY3:
|
||||
byte_length = (num.bit_length() + 7) // 8
|
||||
try:
|
||||
result = num.to_bytes(byte_length, "big", signed=True)
|
||||
# Handles values which require \x00 or \xFF to pad sign-bit
|
||||
except OverflowError:
|
||||
result = num.to_bytes(byte_length + 1, "big", signed=True)
|
||||
else:
|
||||
result = bytes()
|
||||
# 0 and -1 are treated as special cases since they are used as sentinels for all other values
|
||||
if num == 0:
|
||||
result += b'\x00'
|
||||
elif num == -1:
|
||||
result += b'\xFF'
|
||||
elif num > 0:
|
||||
while num >> 32:
|
||||
result = _UINT32.pack(num & _UINT32_MAX) + result
|
||||
num = num >> 32
|
||||
# Pack last 4 bytes individually to discard insignificant bytes
|
||||
while num:
|
||||
result = _UBYTE.pack(num & _UBYTE_MAX) + result
|
||||
num = num >> 8
|
||||
# Zero pad final byte if most-significant bit is 1 as per mpint definition
|
||||
if ord(result[0]) & 0x80:
|
||||
result = b'\x00' + result
|
||||
else:
|
||||
while (num >> 32) < -1:
|
||||
result = _UINT32.pack(num & _UINT32_MAX) + result
|
||||
num = num >> 32
|
||||
while num < -1:
|
||||
result = _UBYTE.pack(num & _UBYTE_MAX) + result
|
||||
num = num >> 8
|
||||
if not ord(result[0]) & 0x80:
|
||||
result = b'\xFF' + result
|
||||
|
||||
return result
|
||||
|
||||
def bytes(self):
|
||||
return bytes(self._buff)
|
||||
|
||||
Reference in New Issue
Block a user