Well, if the DigestValue isn't changing, then it definitely isn't doing what
you want.
My best guess is that the information you want is embedded in the value of the
V Contents. This value is about 17 kB in size, and looks like it contains a
lot of interesting stuff. However, I think it may be a fair amount of work to
decode this, and I don't know if it is worth the effort. I have looked at the
digital signature part of the PDF documentation, and it references some RFC's
that are very hard to follow.
- Phil
