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#!/usr/bin/env python3
import argparse
import re
import struct
import subprocess
import zlib
def main():
parser = argparse.ArgumentParser()
parser.add_argument('--input-file', type=str, required=True)
parser.add_argument('--output-file', type=str, required=True)
parser.add_argument('--model', type=str, required=True)
parser.add_argument('--region', type=str, required=True)
parser.add_argument('--version', type=str, required=True)
parser.add_argument('--encryption-block-size', type=str, required=True)
parser.add_argument('--openssl-bin', type=str, required=True)
parser.add_argument('--key', type=str, required=True)
parser.add_argument('--iv', type=str, required=True)
args = parser.parse_args()
assert re.match(r'V[0-9]\.[0-9]\.[0-9]\.[0-9]',
args.version), 'Version must start with Vx.x.x.x'
encryption_block_size = int(args.encryption_block_size, 0)
assert (encryption_block_size > 0 and encryption_block_size % 16 ==
0), 'Encryption block size must be a multiple of the AES block size (16)'
image = open(args.input_file, 'rb').read()
image_enc = []
for i in range(0, len(image), encryption_block_size):
chunk = image[i:i + encryption_block_size]
chunk += b'\x00' * ((-len(chunk)) % 16) # pad to AES block size (16)
res = subprocess.run([
args.openssl_bin,
'enc',
'-aes-256-cbc',
'-nosalt',
'-nopad',
'-K', args.key,
'-iv', args.iv
],
check=True, input=chunk, stdout=subprocess.PIPE)
image_enc.append(res.stdout)
image_enc = b''.join(image_enc)
image_with_header = struct.pack(
'>32s32s64s64s64s256s12sII',
args.model.encode('ascii'),
args.region.encode('ascii'),
args.version.encode('ascii'),
b'Thu Jan 1 00:00:00 1970', # static date for reproducibility
b'', # reserved
b'', # RSA signature - omitted for now
b'encrpted_img',
len(image_enc),
encryption_block_size,
) + image_enc
checksum = zlib.crc32(image_with_header, 0xffffffff) ^ 0xffffffff
with open(args.output_file, 'wb') as outfile:
outfile.write(image_with_header)
outfile.write(struct.pack('>I', checksum))
if __name__ == "__main__":
main()
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