mefistotelis
commented
1 year ago While public part of the keys was possible to retrieve from the AC, private part is not there. Only DJI has it.
Your options are, either:
- to use a custom key, ie SLAK community key, and hack/root the drone to honor that key before flashing
- to use some kind of cryptofraphic flaw and manually manufacture a binary file which is modified but still accepted by the drone
The most popular method is 1.
top7chip
Hi I don't know if what I want to do is possible. I want to repack a firmware. I am trying to sign the file "wm160_0000v01.00.0500 20200421.pro.cfg.sig" but it gives me this error "Error: Cannot compute image file head signature, auth key 'PRAK' has no private part."
What am I doing wrong?
C:\Users\top\Desktop\MAVIC FIRM\MINI>dji_imah_fwsig.py -vv -k PRAK-2019-09 -s -i wm160_0000_v01.00.0500_20200421.pro.cfg.sig wm160_0000_v01.00.0500_20200421.pro.cfg.sig: Opening for creation and signing wm160_0000_v01.00.0500_20200421.pro.cfg.sig: Warning: Cannot find enc_key ''; scramble key left unencrypted. wm160_0000_v01.00.0500_20200421.pro.cfg.sig: Packing plaintext chunk '0000'... OrderedDict([('id', '0000'), ('offset', 0), ('size', 0), ('attrib', 0), ('address', 0), ('reserved', b'\x00\x00\x00\x00\x00\x00\x00\x00')]) wm160_0000_v01.00.0500_20200421.pro.cfg.sig: Decrypted chunks checksum 0x75CED9F3 stored wm160_0000_v01.00.0500_20200421.pro.cfg.sig: Encrypted data checksum 0x3CD5A0D1 stored OrderedDict([('magic', b'IM*H'), ('header_version', 2), ('size', 1888), ('reserved', b'\x00\x00\x00\x00'), ('header_size', 224), ('signature_size', 256), ('payload_size', 1408), ('target_size', 1888), ('os', 0), ('arch', 0), ('compression', 0), ('anti_version', 0), ('auth_alg', 2), ('auth_key', 'PRAK'), ('enc_key', ''), ('scram_key', b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'), ('name', '0000'), ('type', 'CNFG'), ('version', 16778496), ('date', 538969121), ('encr_cksum', 1020633297), ('reserved2', b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'), ('userdata', b''), ('entry', b'\x00\x00\x00\x00\x00\x00\x00\x00'), ('plain_cksum', 1976490483), ('chunk_num', 1), ('payloaddigest', b']\x86\xab\x82\xf4\x06\x9eP\xe3\xac\2q\xe73\xba,w\xe8L\x1apc\x0f\x1b\xa2\xf6\xac\x8d=\xb2')]) OrderedDict([('id', '0000'), ('offset', 0), ('size', 1378), ('attrib', 0), ('address', 0), ('reserved', b'\x00\x00\x00\x00\x00\x00\x00\x00')]) Error: Cannot compute image file head signature, auth key 'PRAK' has no private part.