Solved: fatal error in vts css key

Most Unix DVD players, and the Popcorn Hour boxes, use libdvdcss to play DVDs and ISO images. Libdvdcss is a fine piece of software and decodes almost all DVDs.

One of the DVDs it cannot play is this version of Moulin Rouge, which uses many different CSS keys, including one libdvdcss (version 1.2.10) cannot crack:

libdvdread: Get key for /VIDEO_TS/VTS_05_1.VOB at 0x0016176c
libdvdcss debug: cracking title key at block 1447788
libdvdcss debug: at block 1451884, still cracking...
libdvdcss debug: at block 1455980, still cracking...
libdvdcss debug: non MPEG block found at block 1457561 (end of title)
libdvdcss debug: end of title reached
libdvdcss debug: successful attempts 0/47, scrambled blocks 2654/9773
libdvdcss debug: title key is 00:00:00:00:00
libdvdcss error: fatal error in vts css key

The other keys on the DVD included ee:8b:93:92:c3, ee:8b:93:92:c4, ee:8b:93:92:c6, ee:8b:93:92:c7 etc, so I guessed what the uncrackable key might be, and wrote it to the key cache file:

$ echo ee:8b:93:92:c5 > ~/.dvdcss/MOULIN_ROUGE_DISC_2-2002011521481300-0000000000/000016176c

Libdvdcss chose the directory name, the file name comes from the first row of the error message.

I hope the other DVDs affected were mastered with the same software as Moulin Rouge, so the same trick will work on them. And I hope that the next version of libdvdcss (1.2.11) will perform this attack automatically.