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# __init__.py - main module
# coding: utf-8
#
# Copyright (C) 2014-2016 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
"""Python module for handling PSKC files
This Python library handles Portable Symmetric Key Container (PSKC) files as
defined in RFC 6030. PSKC files are used to transport and provision symmetric
keys (seed files) to different types of crypto modules, commonly one-time
password tokens or other authentication devices.
This module can be used to extract keys from PSKC files for use in an OTP
authentication system. The module can also be used for authoring PSKC files.
The following prints all keys, decrypting using a password:
>>> from pskc import PSKC
>>> pskc = PSKC('tests/rfc6030/figure7.pskcxml')
>>> pskc.encryption.derive_key('qwerty')
>>> for key in pskc.keys:
... print('%s %s' % (key.serial, str(key.secret.decode())))
987654321 12345678901234567890
The module should be able to handle most common PSKC files.
"""
__all__ = ['PSKC', '__version__']
# the version number of the library
__version__ = '0.4'
class PSKC(object):
"""Wrapper module for parsing a PSKC file.
Instances of this class provide the following attributes:
version: the PSKC format version used (1.0)
id: identifier
encryption: information on used encryption (Encryption instance)
mac: information on used MAC method (MAC instance)
keys: list of keys (Key instances)
"""
def __init__(self, filename=None):
from pskc.encryption import Encryption
from pskc.exceptions import ParseError
from pskc.mac import MAC
self.version = None
self.id = None
self.encryption = Encryption(self)
self.mac = MAC(self)
self.keys = []
if filename is not None:
from pskc.xml import parse, remove_namespaces
try:
tree = parse(filename)
except Exception:
raise ParseError('Error parsing XML')
remove_namespaces(tree)
self.parse(tree.getroot())
else:
self.version = '1.0'
def parse(self, container):
"""Read information from the provided <KeyContainer> tree."""
from pskc.exceptions import ParseError
from pskc.key import Key
from pskc.xml import find, findall
if container.tag != 'KeyContainer':
raise ParseError('Missing KeyContainer')
# the version of the PSKC schema
self.version = container.get('Version')
if self.version != '1.0':
raise ParseError('Unsupported version %r' % self.version)
# unique identifier for the container
self.id = container.get('Id')
# handle EncryptionKey entries
self.encryption.parse(find(container, 'EncryptionKey'))
# handle MACMethod entries
self.mac.parse(find(container, 'MACMethod'))
# handle KeyPackage entries
for key_package in findall(container, 'KeyPackage'):
self.keys.append(Key(self, key_package))
def make_xml(self):
from pskc.xml import mk_elem
container = mk_elem('pskc:KeyContainer', Version=self.version,
Id=self.id)
self.encryption.make_xml(container)
self.mac.make_xml(container)
for key in self.keys:
key.make_xml(container)
return container
def add_key(self, **kwargs):
"""Create a new key instance for the PSKC file.
The new key is initialised with properties from the provided keyword
arguments if any."""
from pskc.key import Key
key = Key(self)
self.keys.append(key)
# assign the kwargs as key properties
for k, v in kwargs.items():
if not hasattr(key, k):
raise AttributeError()
setattr(key, k, v)
return key
def write(self, filename):
"""Write the PSKC file to the provided file."""
from pskc.xml import tostring
if hasattr(filename, 'write'):
xml = tostring(self.make_xml())
try:
filename.write(xml)
except TypeError: # pragma: no cover (Python 3 specific)
# fall back to writing as string for Python 3
filename.write(xml.decode('utf-8'))
else:
with open(filename, 'wb') as output:
self.write(output)
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