feat(handler): add support for Autel ECC firmwares.

unblob/handlers/__init__.py

@@ -1,5 +1,6 @@
 from ..models import DirectoryHandlers, Handlers
 from .archive import ar, arc, arj, cab, cpio, dmg, rar, sevenzip, stuffit, tar, zip
+from .archive.autel import ecc
 from .archive.dlink import encrpted_img, shrs
 from .archive.engeniustech import engenius
 from .archive.hp import bdl, ipkg
@@ -100,6 +101,7 @@
     elf.ELF64Handler,
     zlib.ZlibHandler,
     engenius.EngeniusHandler,
+    ecc.AutelECCHandler,
 )
 
 BUILTIN_DIR_HANDLERS: DirectoryHandlers = (

unblob/handlers/archive/autel/ecc.py

@@ -0,0 +1,334 @@
+from pathlib import Path
+from typing import Optional
+
+from structlog import get_logger
+
+from unblob.file_utils import File, InvalidInputFormat, iterate_file
+from unblob.models import (
+    Endian,
+    Extractor,
+    HexString,
+    StructHandler,
+    StructParser,
+    ValidChunk,
+)
+
+logger = get_logger()
+
+C_DEFINITIONS = r"""
+
+    typedef struct autel_header {
+        char magic[8];
+        uint32 file_size;
+        uint32 header_size;
+        char copyright[16];
+    } autel_header_t;
+"""
+
+KEYS = [
+    (54, 147),
+    (96, 129),
+    (59, 193),
+    (191, 0),
+    (45, 130),
+    (96, 144),
+    (27, 129),
+    (152, 0),
+    (44, 180),
+    (118, 141),
+    (115, 129),
+    (210, 0),
+    (13, 164),
+    (27, 133),
+    (20, 192),
+    (139, 0),
+    (28, 166),
+    (17, 133),
+    (19, 193),
+    (224, 0),
+    (20, 161),
+    (145, 0),
+    (14, 193),
+    (12, 132),
+    (18, 161),
+    (17, 140),
+    (29, 192),
+    (246, 0),
+    (115, 178),
+    (28, 132),
+    (155, 0),
+    (12, 132),
+    (31, 165),
+    (20, 136),
+    (27, 193),
+    (142, 0),
+    (96, 164),
+    (18, 133),
+    (145, 0),
+    (23, 132),
+    (13, 165),
+    (13, 148),
+    (23, 193),
+    (19, 132),
+    (27, 178),
+    (83, 137),
+    (146, 0),
+    (145, 0),
+    (18, 166),
+    (96, 148),
+    (13, 193),
+    (159, 0),
+    (96, 166),
+    (20, 129),
+    (20, 193),
+    (27, 132),
+    (9, 160),
+    (96, 148),
+    (13, 192),
+    (159, 0),
+    (96, 180),
+    (142, 0),
+    (31, 193),
+    (155, 0),
+    (7, 166),
+    (224, 0),
+    (20, 192),
+    (27, 132),
+    (28, 160),
+    (17, 149),
+    (19, 193),
+    (96, 132),
+    (76, 164),
+    (208, 0),
+    (80, 192),
+    (78, 132),
+    (96, 160),
+    (27, 144),
+    (24, 193),
+    (140, 0),
+    (96, 178),
+    (17, 141),
+    (12, 193),
+    (224, 0),
+    (14, 161),
+    (17, 141),
+    (151, 0),
+    (14, 132),
+    (16, 165),
+    (96, 137),
+    (13, 193),
+    (155, 0),
+    (20, 161),
+    (29, 141),
+    (23, 192),
+    (24, 132),
+    (27, 178),
+    (10, 133),
+    (96, 192),
+    (140, 0),
+    (14, 180),
+    (17, 133),
+    (16, 192),
+    (144, 0),
+    (11, 163),
+    (13, 141),
+    (96, 192),
+    (17, 132),
+    (12, 178),
+    (96, 141),
+    (28, 192),
+    (27, 132),
+    (27, 130),
+    (18, 141),
+    (96, 193),
+    (31, 132),
+    (96, 181),
+    (13, 140),
+    (23, 193),
+    (224, 0),
+    (27, 166),
+    (142, 0),
+    (27, 192),
+    (24, 132),
+    (12, 183),
+    (96, 133),
+    (84, 192),
+    (14, 132),
+    (27, 178),
+    (10, 140),
+    (155, 0),
+    (9, 132),
+    (17, 160),
+    (56, 133),
+    (96, 192),
+    (82, 132),
+    (13, 160),
+    (27, 137),
+    (20, 193),
+    (139, 0),
+    (28, 161),
+    (145, 0),
+    (19, 192),
+    (118, 132),
+    (115, 165),
+    (20, 132),
+    (145, 0),
+    (14, 132),
+    (12, 167),
+    (146, 0),
+    (17, 193),
+    (29, 132),
+    (96, 176),
+    (28, 144),
+    (27, 193),
+    (140, 0),
+    (31, 180),
+    (148, 0),
+    (27, 192),
+    (14, 132),
+    (83, 160),
+    (18, 137),
+    (17, 193),
+    (23, 132),
+    (13, 165),
+    (13, 145),
+    (151, 0),
+    (147, 0),
+    (27, 178),
+    (96, 137),
+    (19, 193),
+    (159, 0),
+    (14, 160),
+    (25, 148),
+    (17, 193),
+    (142, 0),
+    (16, 180),
+    (27, 136),
+    (14, 193),
+    (224, 0),
+    (17, 178),
+    (12, 144),
+    (224, 0),
+    (28, 132),
+    (27, 160),
+    (13, 141),
+    (11, 193),
+    (96, 132),
+    (27, 165),
+    (30, 140),
+    (224, 0),
+    (146, 0),
+    (31, 165),
+    (29, 129),
+    (96, 192),
+    (140, 0),
+    (31, 161),
+    (24, 145),
+    (140, 0),
+    (96, 132),
+    (27, 165),
+    (29, 140),
+    (31, 192),
+    (154, 0),
+    (14, 161),
+    (27, 145),
+    (140, 0),
+    (18, 132),
+    (23, 167),
+    (96, 140),
+    (21, 129),
+    (14, 132),
+    (17, 165),
+    (9, 137),
+    (12, 193),
+    (155, 0),
+    (18, 161),
+    (96, 141),
+    (27, 192),
+    (148, 0),
+    (29, 178),
+    (23, 133),
+    (24, 192),
+    (155, 0),
+    (10, 180),
+    (96, 133),
+    (28, 192),
+    (14, 132),
+    (31, 130),
+    (28, 129),
+    (18, 193),
+    (31, 132),
+    (12, 180),
+    (13, 144),
+    (96, 193),
+    (31, 132),
+    (96, 160),
+    (13, 141),
+    (27, 193),
+    (18, 132),
+    (23, 181),
+    (26, 140),
+    (27, 193),
+    (156, 0),
+    (96, 166),
+    (79, 141),
+    (211, 0),
+    (76, 132),
+    (77, 160),
+    (75, 133),
+    (206, 0),
+    (182, 0),
+    (96, 129),
+    (59, 133),
+    (191, 0),
+    (173, 0),
+]
+
+
+def ecc_decode(data: bytes):
+    """Decode a 256 byte data block."""
+    assert len(data) <= 256
+    for i, value in enumerate(data):
+        a, b = KEYS[i]
+        yield ((value + a) ^ b) % 256
+
+
+class ECCExtractor(Extractor):
+    def __init__(self):
+        self._struct_parser = StructParser(C_DEFINITIONS)
+
+    def extract(self, inpath: Path, outdir: Path):
+        outpath = outdir.joinpath(f"{inpath.name}.decrypted")
+        with File.from_path(inpath) as file:
+            header = self._struct_parser.parse(
+                "autel_header_t", file, endian=Endian.LITTLE
+            )
+            with outpath.open("wb") as outfile:
+                for data in iterate_file(
+                    file, header.header_size, header.file_size, 256
+                ):
+                    outfile.write(bytes(ecc_decode(data)))
+
+
+class AutelECCHandler(StructHandler):
+    NAME = "ecc"
+
+    PATTERNS = [HexString("45 43 43 30 31 30 31 00")]
+
+    C_DEFINITIONS = C_DEFINITIONS
+    HEADER_STRUCT = "autel_header_t"
+    EXTRACTOR = ECCExtractor()
+
+    def is_valid_header(self, header) -> bool:
+        return header.header_size == 0x20
+
+    def calculate_chunk(self, file: File, start_offset: int) -> Optional[ValidChunk]:
+        header = self.parse_header(file, endian=Endian.LITTLE)
+
+        if not self.is_valid_header(header):
+            raise InvalidInputFormat("Invalid ECC header.")
+
+        return ValidChunk(
+            start_offset=start_offset,
+            end_offset=start_offset + header.header_size + header.file_size,
+        )