46 lines
1.6 KiB
Python
46 lines
1.6 KiB
Python
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import struct
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from crccheck.crc import Crc32Mpeg2
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class Keybox:
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def __init__(self, data):
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length = len(data)
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if length not in (128, 132):
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raise ValueError(f"Invalid keybox length: {length}. Should be 128 or 132 bytes")
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if length == 128: # QSEE style keybox
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if data[0x80:0x84] != b"LVL1":
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raise ValueError("QSEE style keybox does not end in bytes 'LVL1'")
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data = data[0:0x80]
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if data[0x78:0x7C] != b"kbox":
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raise ValueError("Invalid keybox magic")
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body_crc = Crc32Mpeg2.calc(data[:0x7C])
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body_crc_expected = struct.unpack(">L", data[0x7C:0x7C + 4])[0]
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if body_crc_expected != body_crc:
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raise ValueError(f"Keybox CRC is bad. Expected: 0x{body_crc_expected:08X}. Computed: 0x{body_crc:08X}")
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self.stable_id = data[0x00:0x20] # aka device ID
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self.device_aes_key = data[0x20:0x30]
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self.device_id = data[0x30:0x78] # device id sent to google, possibly flags + system_id + encrypted
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# known fields
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self.flags, self.system_id = struct.unpack(">L", self.device_id[0:8])[:2]
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def __str__(self):
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return f"{self.stable_id.decode('utf-8').strip()} ({self.system_id})"
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def __repr__(self):
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return "{name}({items})".format(
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name=self.__class__.__name__,
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items=", ".join([f"{k}={repr(v)}" for k, v in self.__dict__.items()])
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)
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@classmethod
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def load(cls, file):
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"""Load Keybox from a file path."""
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with open(file, "rb", encoding="utf-8") as fd:
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return cls(fd.read())
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