The firmware transforms the reply (16-round Feistel per 8-byte record) and
compares it with the host-order copy of the challenge, so the answer is
swap4(inverse_transform(swap4(challenge))). The font stages are memcpy in
this path because dwt_prf initialises only mode 1.
challenge.py implements the transform and its inverse using the firmware's
fixed key/SP table; solve.py answers the challenge over TCP using the
unmodified exploit client. 320 forward vectors, the firmware's own inverse
and three live sessions validate it. A live run with no breakpoints poked
the 82-byte hello-world payload and ran it: MAGIC DEAD/BEEF/0400, VRAM
1024/1024. Notes and evidence under dwt/notes and dwt/evidence.
SDD