H12SSL Image not working

[desultory]

Using the latest version in master, and firmware BMC_H12AST2500-ROT-2201MS-GPIO01_20240313_01.04.03_STDsp.bin

./smcbmc.py ~/tmp/BMC_H12AST2500-ROT-2201MS-GPIO01_20240313_01.04.03_STDsp.bin out.img
Traceback (most recent call last):
  File "/home/desu/projects/smcbmc/./smcbmc.py", line 104, in <module>
    decrypt_image(args.infile, args.outfile)
  File "/home/desu/projects/smcbmc/./smcbmc.py", line 92, in decrypt_image
    regions = extract_keys(mm)
              ^^^^^^^^^^^^^^^^
  File "/home/desu/projects/smcbmc/./smcbmc.py", line 42, in extract_keys
    mm.seek(inode_off - 8)
ValueError: seek out of range

Maybe I'm using the wrong file, or the image format has changed? I see there are unencrypted portions, but don't know where to look.