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javacard: add parser for JAVA-card CAP file format

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To install JAVA-card applets we need to be able to extract the executeable
loadfile and the AIDs of the applet and the loadfile. This patch adds the
parser and related unittests.

Related: OS#6679
Change-Id: I581483ccb9d8a254fcecc995fec3c811c5cf38eb
This commit is contained in:
Philipp Maier
2024-12-19 17:59:51 +01:00
parent 6d2e3853b4
commit 712946eddb
3 changed files with 140 additions and 1 deletions
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123
pySim/javacard.py
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@@ -1,9 +1,30 @@
# JavaCard related utilities
#
# (C) 2024 by Sysmocom s.f.m.c. GmbH
# All Rights Reserved
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 2 of the License, or
# (at your option) any later version.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
import zipfile
import struct
import sys
import io
from osmocom.utils import b2h, Hexstr
from construct import Struct, Array, this, Int32ub, Int16ub, Int8ub
from osmocom.construct import *
from osmocom.tlv import *
from construct import Optional as COptional
def ijc_to_cap(in_file: io.IOBase, out_zip: zipfile.ZipFile, p : str = "foo"):
"""Convert an ICJ (Interoperable Java Card) file [back] to a CAP file.
@@ -19,3 +40,103 @@ def ijc_to_cap(in_file: io.IOBase, out_zip: zipfile.ZipFile, p : str = "foo"):
out_zip.writestr(p+"/javacard/"+TAGS[tag-1]+".cap", b[0:3+size])
b = b[3+size:]
class CapFile():
# Java Card Platform Virtual Machine Specification, v3.2, section 6.4
__header_component_compact = Struct('tag'/Int8ub,
'size'/Int16ub,
'magic'/Int32ub,
'minor_version'/Int8ub,
'major_version'/Int8ub,
'flags'/Int8ub,
'package'/Struct('minor_version'/Int8ub,
'major_version'/Int8ub,
'AID'/LV),
'package_name'/COptional(LV)) #since CAP format 2.2
# Java Card Platform Virtual Machine Specification, v3.2, section 6.6
__applet_component_compact = Struct('tag'/Int8ub,
'size'/Int16ub,
'count'/Int8ub,
'applets'/Array(this.count, Struct('AID'/LV,
'install_method_offset'/Int16ub)),
)
def __init__(self, filename:str):
# In this dictionary we will keep all nested .cap file components by their file names (without .cap suffix)
# See also: Java Card Platform Virtual Machine Specification, v3.2, section 6.2.1
self.__component = {}
# Extract the nested .cap components from the .cap file
# See also: Java Card Platform Virtual Machine Specification, v3.2, section 6.2.1
cap = zipfile.ZipFile(filename)
cap_namelist = cap.namelist()
for i, filename in enumerate(cap_namelist):
if filename.lower().endswith('.capx') and not filename.lower().endswith('.capx'):
#TODO: At the moment we only support the compact .cap format, add support for the extended .cap format.
raise ValueError("incompatible .cap file, extended .cap format not supported!")
if filename.lower().endswith('.cap'):
key = filename.split('/')[-1].removesuffix('.cap')
self.__component[key] = cap.read(filename)
# Make sure that all mandatory components are present
# See also: Java Card Platform Virtual Machine Specification, v3.2, section 6.2
required_components = {'Header' : 'COMPONENT_Header',
'Directory' : 'COMPONENT_Directory',
'Import' : 'COMPONENT_Import',
'ConstantPool' : 'COMPONENT_ConstantPool',
'Class' : 'COMPONENT_Class',
'Method' : 'COMPONENT_Method',
'StaticField' : 'COMPONENT_StaticField',
'RefLocation' : 'COMPONENT_ReferenceLocation',
'Descriptor' : 'COMPONENT_Descriptor'}
for component in required_components:
if component not in self.__component.keys():
raise ValueError("invalid cap file, %s missing!" % required_components[component])
def get_loadfile(self) -> bytes:
"""Get the executeable loadfile as hexstring"""
# Concatenate all cap file components in the specified order
# see also: Java Card Platform Virtual Machine Specification, v3.2, section 6.3
loadfile = self.__component['Header']
loadfile += self.__component['Directory']
loadfile += self.__component['Import']
if 'Applet' in self.__component.keys():
loadfile += self.__component['Applet']
loadfile += self.__component['Class']
loadfile += self.__component['Method']
loadfile += self.__component['StaticField']
if 'Export' in self.__component.keys():
loadfile += self.__component['Export']
loadfile += self.__component['ConstantPool']
loadfile += self.__component['RefLocation']
if 'Descriptor' in self.__component.keys():
loadfile += self.__component['Descriptor']
return loadfile
def get_loadfile_aid(self) -> Hexstr:
"""Get the loadfile AID as hexstring"""
header = self.__header_component_compact.parse(self.__component['Header'])
magic = header['magic'] or 0
if magic != 0xDECAFFED:
raise ValueError("invalid cap file, COMPONENT_Header lacks magic number (0x%08X!=0xDECAFFED)!" % magic)
#TODO: check cap version and make sure we are compatible with it
return header['package']['AID']
def get_applet_aid(self, index:int = 0) -> Hexstr:
"""Get the applet AID as hexstring"""
#To get the module AID, we must look into COMPONENT_Applet. Unfortunately, even though this component should
#be present in any .cap file, it is defined as an optional component.
if 'Applet' not in self.__component.keys():
raise ValueError("can't get the AID, this cap file lacks the optional COMPONENT_Applet component!")
applet = self.__applet_component_compact.parse(self.__component['Applet'])
if index > applet['count']:
raise ValueError("can't get the AID for applet with index=%u, this .cap file only has %u applets!" %
(index, applet['count']))
return applet['applets'][index]['AID']

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tests/unittests/test_javacard.cap Normal file
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18
tests/unittests/test_javacard.py Executable file
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@@ -0,0 +1,18 @@
#!/usr/bin/env python3
import os
import unittest
from pySim.javacard import *
class TestJavacard(unittest.TestCase):
def test_CapFile(self):
loadfile="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"
cap = CapFile(os.path.dirname(os.path.abspath(__file__)) + "/test_javacard.cap")
self.assertTrue(b2h(cap.get_loadfile()) == loadfile)
self.assertTrue(cap.get_loadfile_aid() == "d07002ca44")
self.assertTrue(cap.get_applet_aid() == "d07002ca44900101")
if __name__ == "__main__":
unittest.main()