Hi, everybody:
when my filter encrypt the .doc file,
if I modify the .doc’s context and save and quit the word,
when reboot next time, the .doc cannot opened!
This problem happens when the .doc’s size is larger than 64K,
my target filesystem is fat32, so it’s not the stream;
in my filter, I get and hash the target file in IRP_MJ_CREATE,
decrypt the target file’s content in IRP_MJ_READ when NO_CACHE
or PAGINGIO, also encrypt the content in IRP_MJ_WRITE for NO_CACHE
or PAGINGIO.
when I view the should encrypt .doc file, I found some part of
content was not encrypted. So I tracing the IRP in softice during
changing the content of .doc and found all content was read out and
write back.
Is there anything missing in my filter’s design?
or some problem with the cooperation of explorer?
or some proble Word’s strategy when open and save back?
this problem has feaze me for one week and delayed the process
of the filter’s implemention. I still have more work to be done,
such as changing the file size and target the NTFS.
any help is wellcome.