tools/crx_id/crx_id.py

   1 #!/usr/bin/env python
   2 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
   3 # Use of this source code is governed by a BSD-style license that can be
   4 # found in the LICENSE file.
   5
   6 """ Read a CRX file and write out the App ID and the Full Hash of the ID.
   7 See: http://code.google.com/chrome/extensions/crx.html
   8 and 'http://stackoverflow.com/questions/'
   9   + '1882981/google-chrome-alphanumeric-hashes-to-identify-extensions'
  10 for docs on the format.
  11 """
  12
  13 import base64
  14 import os
  15 import sys
  16 import hashlib
  17
  18 try:
  19   import json
  20 except Exception:
  21   import simplejson as json
  22
  23 EXPECTED_CRX_MAGIC_NUM = 'Cr24'
  24 EXPECTED_CRX_VERSION = 2
  25
  26 def usage(argv):
  27   print "%s: crx_file" % argv[0]
  28
  29 def HexToInt(hex_chars):
  30   """ Convert bytes like \xab -> 171 """
  31   val = 0
  32   for i in xrange(len(hex_chars)):
  33     val += pow(256, i) * ord(hex_chars[i])
  34   return val
  35
  36 def HexToMPDecimal(hex_chars):
  37   """ Convert bytes to an MPDecimal string. Example \x00 -> "aa"
  38       This gives us the AppID for a chrome extension.
  39   """
  40   result = ''
  41   base = ord('a')
  42   for i in xrange(len(hex_chars)):
  43     value = ord(hex_chars[i])
  44     dig1 = value / 16
  45     dig2 = value % 16
  46     result += chr(dig1 + base)
  47     result += chr(dig2 + base)
  48   return result
  49
  50 def HexTo256(hex_chars):
  51   """ Convert bytes to pairs of hex digits. E.g., \x00\x11 -> "{0x00, 0x11}"
  52       The format is taylored for copy and paste into C code:
  53       const uint8 sha256_hash[] = { ... }; """
  54   result = []
  55   for i in xrange(len(hex_chars)):
  56     value = ord(hex_chars[i])
  57     dig1 = value / 16
  58     dig2 = value % 16
  59     result.append('0x' + hex(dig1)[2:] + hex(dig2)[2:])
  60   return '{%s}' % ', '.join(result)
  61
  62 def GetPublicKeyPacked(f):
  63   magic_num = f.read(4)
  64   if magic_num != EXPECTED_CRX_MAGIC_NUM:
  65     raise Exception('Invalid magic number: %s (expecting %s)' %
  66                     (magic_num,
  67                      EXPECTED_CRX_MAGIC_NUM))
  68   version = f.read(4)
  69   if not version[0] != EXPECTED_CRX_VERSION:
  70     raise Exception('Invalid version number: %s (expecting %s)' %
  71                     (version,
  72                      EXPECTED_CRX_VERSION))
  73   pub_key_len_bytes = HexToInt(f.read(4))
  74   sig_len_bytes = HexToInt(f.read(4))
  75   pub_key = f.read(pub_key_len_bytes)
  76   return pub_key
  77
  78 def GetPublicKeyFromPath(filepath):
  79   # Normalize the path for windows to have capital drive letters.
  80   # We intentionally don't check if sys.platform == 'win32' and just
  81   # check if this looks like drive letter so that we can test this
  82   # even on posix systems.
  83   if (len(filepath) >= 2 and
  84       filepath[0].islower() and
  85       filepath[1] == ':'):
  86       return filepath[0].upper() + filepath[1:]
  87   return filepath
  88
  89 def GetPublicKeyUnpacked(f, filepath):
  90   manifest = json.load(f)
  91   if 'key' not in manifest:
  92     # Use the path as the public key.
  93     # See Extension::GenerateIdForPath in extension.cc
  94     return GetPublicKeyFromPath(filepath)
  95   else:
  96     return base64.standard_b64decode(manifest['key'])
  97
  98 def HasPublicKey(filename):
  99   if os.path.isdir(filename):
 100     with open(os.path.join(filename, 'manifest.json'), 'rb') as f:
 101       manifest = json.load(f)
 102       return 'key' in manifest
 103   return False
 104
 105 def GetPublicKey(filename, from_file_path):
 106   if from_file_path:
 107     return GetPublicKeyFromPath(filename)
 108
 109   pub_key = ''
 110   if os.path.isdir(filename):
 111     # Assume it's an unpacked extension
 112     f = open(os.path.join(filename, 'manifest.json'), 'rb')
 113     pub_key = GetPublicKeyUnpacked(f, filename)
 114     f.close()
 115   else:
 116     # Assume it's a packed extension.
 117     f = open(filename, 'rb')
 118     pub_key = GetPublicKeyPacked(f)
 119     f.close()
 120   return pub_key
 121
 122 def GetCRXHash(filename, from_file_path=False):
 123   pub_key = GetPublicKey(filename, from_file_path)
 124   pub_key_hash = hashlib.sha256(pub_key).digest()
 125   return HexTo256(pub_key_hash)
 126
 127 def GetCRXAppID(filename, from_file_path=False):
 128   pub_key = GetPublicKey(filename, from_file_path)
 129   pub_key_hash = hashlib.sha256(pub_key).digest()
 130   # AppID is the MPDecimal of only the first 128 bits of the hash.
 131   return HexToMPDecimal(pub_key_hash[:128/8])
 132
 133 def main(argv):
 134   if len(argv) != 2:
 135     usage(argv)
 136     return 1
 137   print 'Raw Bytes: %s' % GetCRXHash(sys.argv[1])
 138   print 'AppID: %s' % GetCRXAppID(sys.argv[1])
 139
 140
 141 if __name__ == '__main__':
 142   sys.exit(main(sys.argv))