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Sercomm firmwares are encrypted with AES 256 CBC. The key is generated with a custom algorithm from the firmware tag: char key[32]; char version[32]; char iv[32]; char random[32]; char size[32]; Key must be generated with Sercomm's algorithm. However, the rest of the header can be empty. IV and random are set to 0 on purpose. Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
87 lines
1.7 KiB
Python
Executable File
87 lines
1.7 KiB
Python
Executable File
#!/usr/bin/env python3
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import argparse
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import binascii
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import hashlib
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import os
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import struct
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def create_header(key, version, iv, random, size):
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header = struct.pack('32s32s32s32s32s', key, version, iv, random, size)
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return header
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def create_output(args):
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in_st = os.stat(args.input_file)
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in_size = in_st.st_size
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key = "".encode('ascii')
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version = args.version.encode('ascii')
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iv = "".encode('ascii')
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random = "".encode('ascii')
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size = str(in_size).encode('ascii')
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header = create_header(key, version, iv, random, size)
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out_f = open(args.output_file, 'w+b')
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out_f.write(header)
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out_f.close()
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md5 = hashlib.md5()
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md5.update(header[0x60:0x80])
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md5.update(header[0x20:0x40])
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md5_1 = md5.digest()
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md5 = hashlib.md5()
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md5.update(header[0x80:0xA0])
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md5.update(header[0x20:0x40])
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md5_2 = md5.digest()
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key = md5_1 + md5_2
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key_f = open(args.key_file, 'w+b')
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key_f.write(binascii.hexlify(bytearray(key)))
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key_f.close()
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print("AES 256 CBC Key:", binascii.hexlify(bytearray(key)))
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def main():
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global args
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parser = argparse.ArgumentParser(description='')
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parser.add_argument('--input-file',
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dest='input_file',
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action='store',
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type=str,
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help='Input file')
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parser.add_argument('--key-file',
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dest='key_file',
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action='store',
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type=str,
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help='AES 256 CBC Key File')
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parser.add_argument('--output-file',
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dest='output_file',
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action='store',
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type=str,
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help='Output file')
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parser.add_argument('--version',
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dest='version',
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action='store',
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type=str,
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help='Version')
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args = parser.parse_args()
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if ((not args.input_file) or
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(not args.key_file) or
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(not args.output_file) or
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(not args.version)):
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parser.print_help()
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create_output(args)
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main()
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