You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
103 lines
3.0 KiB
103 lines
3.0 KiB
1 year ago
|
try:
|
||
|
|
from google.protobuf.internal.decoder import _DecodeVarint as _di # this was tested to work with protobuf 3, but it's an internal API (any varint decoder might work)
|
||
|
|
except ImportError:
|
||
|
|
# this is generic and does not depend on pb internals, however it will decode "larger" possible numbers than pb decoder which has them fixed
|
||
|
|
def LEB128_decode(buffer, pos, limit = 64):
|
||
|
|
result = 0
|
||
|
|
shift = 0
|
||
|
|
while True:
|
||
|
|
b = buffer[pos]
|
||
|
|
pos += 1
|
||
|
|
result |= ((b & 0x7F) << shift)
|
||
|
|
if not (b & 0x80):
|
||
|
|
return (result, pos)
|
||
|
|
shift += 7
|
||
|
|
if shift > limit:
|
||
|
|
raise Exception("integer too large, shift: {}".format(shift))
|
||
|
|
_di = LEB128_decode
|
||
|
|
|
||
|
|
|
||
|
|
class FromFileMixin:
|
||
|
|
@classmethod
|
||
|
|
def from_file(cls, filename):
|
||
|
|
"""Load given a filename"""
|
||
|
|
with open(filename,"rb") as f:
|
||
|
|
return cls(f.read())
|
||
|
|
|
||
|
|
# the signatures use a format internally similar to
|
||
|
|
# protobuf's encoding, but without wire types
|
||
|
|
class VariableReader(FromFileMixin):
|
||
|
|
"""Protobuf-like encoding reader"""
|
||
|
|
|
||
|
|
def __init__(self, buf):
|
||
|
|
self.buf = buf
|
||
|
|
self.pos = 0
|
||
|
|
self.size = len(buf)
|
||
|
|
|
||
|
|
def read_int(self):
|
||
|
|
"""Read a variable length integer"""
|
||
|
|
# _DecodeVarint will take care of out of range errors
|
||
|
|
(val, nextpos) = _di(self.buf, self.pos)
|
||
|
|
self.pos = nextpos
|
||
|
|
return val
|
||
|
|
|
||
|
|
def read_bytes_raw(self, size):
|
||
|
|
"""Read size bytes"""
|
||
|
|
b = self.buf[self.pos:self.pos+size]
|
||
|
|
self.pos += size
|
||
|
|
return b
|
||
|
|
|
||
|
|
def read_bytes(self):
|
||
|
|
"""Read a bytes object"""
|
||
|
|
size = self.read_int()
|
||
|
|
return self.read_bytes_raw(size)
|
||
|
|
|
||
|
|
def is_end(self):
|
||
|
|
return (self.size == self.pos)
|
||
|
|
|
||
|
|
|
||
|
|
class TaggedReader(VariableReader):
|
||
|
|
"""Tagged reader, needed for implementing a WideVine signature reader"""
|
||
|
|
|
||
|
|
def read_tag(self):
|
||
|
|
"""Read a tagged buffer"""
|
||
|
|
return (self.read_int(), self.read_bytes())
|
||
|
|
|
||
|
|
def read_all_tags(self, max_tag=3):
|
||
|
|
tags = {}
|
||
|
|
while (not self.is_end()):
|
||
|
|
(tag, bytes) = self.read_tag()
|
||
|
|
if (tag > max_tag):
|
||
|
|
raise IndexError("tag out of bound: got {}, max {}".format(tag, max_tag))
|
||
|
|
|
||
|
|
tags[tag] = bytes
|
||
|
|
return tags
|
||
|
|
|
||
|
|
class WideVineSignatureReader(FromFileMixin):
|
||
|
|
"""Parses a widevine .sig signature file."""
|
||
|
|
|
||
|
|
SIGNER_TAG = 1
|
||
|
|
SIGNATURE_TAG = 2
|
||
|
|
ISMAINEXE_TAG = 3
|
||
|
|
|
||
|
|
def __init__(self, buf):
|
||
|
|
reader = TaggedReader(buf)
|
||
|
|
self.version = reader.read_int()
|
||
|
|
if (self.version != 0):
|
||
|
|
raise Exception("Unsupported signature format version {}".format(self.version))
|
||
|
|
self.tags = reader.read_all_tags()
|
||
|
|
|
||
|
|
self.signer = self.tags[self.SIGNER_TAG]
|
||
|
|
self.signature = self.tags[self.SIGNATURE_TAG]
|
||
|
|
|
||
|
|
extra = self.tags[self.ISMAINEXE_TAG]
|
||
|
|
if (len(extra) != 1 or (extra[0] > 1)):
|
||
|
|
raise Exception("Unexpected 'ismainexe' field value (not '\\x00' or '\\x01'), please check: {0}".format(extra))
|
||
|
|
|
||
|
|
self.mainexe = bool(extra[0])
|
||
|
|
|
||
|
|
@classmethod
|
||
|
|
def get_tags(cls, filename):
|
||
|
|
"""Return a dictionary of each tag in the signature file"""
|
||
|
|
return cls.from_file(filename).tags
|