/usr/lib/python3/dist-packages/pskc/key.py is in python3-pskc 1.0-1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 | # key.py - module for handling keys from pskc files
# coding: utf-8
#
# Copyright (C) 2014-2017 Arthur de Jong
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301 USA
"""Module that handles keys stored in PSKC files."""
import array
import binascii
from pskc.policy import Policy
class EncryptedValue(object):
"""A container for an encrypted value."""
def __init__(self, cipher_value, mac_value, algorithm):
self.cipher_value = cipher_value
self.mac_value = mac_value
self.algorithm = algorithm
@classmethod
def create(cls, pskc, value):
# force conversion to bytestring on Python 3
if not isinstance(value, type(b'')):
value = value.encode() # pragma: no cover (Python 3 specific)
cipher_value = pskc.encryption.encrypt_value(value)
mac_value = None
if pskc.mac.algorithm:
mac_value = pskc.mac.generate_mac(cipher_value)
return cls(cipher_value, mac_value, pskc.encryption.algorithm)
def get_value(self, pskc):
"""Provide the decrypted value."""
from pskc.exceptions import DecryptionError
plaintext = pskc.encryption.decrypt_value(
self.cipher_value, self.algorithm)
# allow MAC over plaintext or cipertext
# (RFC6030 implies MAC over ciphertext but older draft used
# MAC over plaintext)
if self.mac_value and self.mac_value not in (
pskc.mac.generate_mac(self.cipher_value),
pskc.mac.generate_mac(plaintext)):
raise DecryptionError('MAC value does not match')
return plaintext
class EncryptedIntegerValue(EncryptedValue):
@classmethod
def create(cls, pskc, value):
value = '%x' % value
n = len(value)
value = binascii.unhexlify(value.zfill(n + (n & 1)))
return super(EncryptedIntegerValue, cls).create(pskc, value)
def get_value(self, pskc):
"""Provide the decrypted integer value."""
value = super(EncryptedIntegerValue, self).get_value(pskc)
# try to handle value as ASCII representation
if value.isdigit():
return int(value)
# fall back to do big-endian decoding
result = 0
for x in array.array('B', value):
result = (result << 8) + x
return result
class DataTypeProperty(object):
"""A data descriptor that delegates actions to DataType instances."""
def __init__(self, name, doc):
self.name = name
self.__doc__ = doc
def __get__(self, obj, objtype):
value = getattr(obj, '_' + self.name, None)
if hasattr(value, 'get_value'):
return value.get_value(obj.device.pskc)
else:
return value
def __set__(self, obj, val):
setattr(obj, '_' + self.name, val)
class DeviceProperty(object):
"""A data descriptor that delegates actions to the Device instance."""
def __init__(self, name):
self.name = name
def __get__(self, obj, objtype):
return getattr(obj.device, self.name)
def __set__(self, obj, val):
setattr(obj.device, self.name, val)
class Key(object):
"""Representation of a single key from a PSKC file.
Instances of this class provide the following properties:
id: unique key identifier (should be constant between interchanges)
algorithm: identifier of the PSKC algorithm profile (URI)
secret: the secret key itself (binary form, automatically decrypted)
counter: event counter for event-based OTP
time_offset: time offset for time-based OTP algorithms (in intervals)
time_interval: time interval for time-based OTP in seconds
time_drift: device clock drift (negative means device is slow)
issuer: party that issued the key
key_profile: reference to pre-shared key profile information
key_reference: reference to an external key
friendly_name: human-readable name for the secret key
key_userid: user distinguished name associated with the key
algorithm_suite: additional algorithm characteristics (e.g. used hash)
challenge_encoding: format of the challenge for CR devices
challenge_min_length: minimum accepted challenge length by device
challenge_max_length: maximum size challenge accepted by the device
challenge_check: whether the device will check an embedded check digit
response_encoding: format of the response the device will generate
response_length: the length of the response of the device
response_check: whether the device appends a Luhn check digit
policy: reference to policy information (see Policy class)
This class also provides access to the manufacturer, serial, model,
issue_no, device_binding, start_date, expiry_date, device_userid and
crypto_module properties of the Device class.
"""
def __init__(self, device):
self.device = device
self.id = None
self.algorithm = None
self.issuer = None
self.key_profile = None
self.key_reference = None
self.friendly_name = None
self.key_userid = None
self.algorithm_suite = None
self.challenge_encoding = None
self.challenge_min_length = None
self.challenge_max_length = None
self.challenge_check = None
self.response_encoding = None
self.response_length = None
self.response_check = None
self.policy = Policy(self)
secret = DataTypeProperty(
'secret', 'The secret key itself.')
counter = DataTypeProperty(
'counter', 'An event counter for event-based OTP.')
time_offset = DataTypeProperty(
'time_offset',
'A time offset for time-based OTP (number of intervals).')
time_interval = DataTypeProperty(
'time_interval', 'A time interval in seconds.')
time_drift = DataTypeProperty(
'time_drift', 'Device clock drift value (number of time intervals).')
manufacturer = DeviceProperty('manufacturer')
serial = DeviceProperty('serial')
model = DeviceProperty('model')
issue_no = DeviceProperty('issue_no')
device_binding = DeviceProperty('device_binding')
start_date = DeviceProperty('start_date')
expiry_date = DeviceProperty('expiry_date')
device_userid = DeviceProperty('device_userid')
crypto_module = DeviceProperty('crypto_module')
def check(self):
"""Check if all MACs in the message are valid."""
if all(x is not False for x in (
self.secret, self.counter, self.time_offset,
self.time_interval, self.time_drift)):
return True
@property
def userid(self):
"""User identifier (either the key or device userid)."""
return self.key_userid or self.device_userid
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