I started using Keepass about a month ago to hold my passwords and online accounts info. Everything was stored in a single .kdb file, only protected with a password. I'm using Windows 7.

Now Keepass can't open my .kdb file with the error "Invalid/wrong key".

I'm fairly confident I have the right password. Altough I might have mixed up a few letters I've tried about two dozen different combinations to minimize that possibility - but can't rule it out though.

My guess is however that the .kdb file got corrupted, either due to Dropbox syncing (only using it on one computer though) or because I edited the file using KeePassX on Ubuntu (dual boot on the same computer, accessing a mounted Win7 NTFS partition), or possibly a combination of both.

I have tried restoring older versions(even the original one) from Dropbox and trying out all possible passwords without any luck. (which does seem to rule out KeePassX as the culprit, since oldest copies are before I edited the file from Ubuntu) I have tried opening the file with the "Repair KeePass Database file" which always gives the "0xA Invalid/corrupt file structure" (the same error for when a wrong password is typed).

I was wondering if there was any way for me to salvage my hard-gathered data. I know generally that brute force cracking is not feasible, but since I can remember probably more than half of the usernames/passwords, any maybe the fact that one of them does come up fairly often (my go-to pass for trivial stuff), that might simplify the brute force process to a doable time frame. Maybe the brute-force thing might incorporate the fact that I know the password length and what characters it's made from. (If we assume corruption, not a password-blackout on my part)

I could do some programming if there are any libraries or routines that I could use.

Other people seem to have had a similar probem
http://forums.dropbox.com/topic.php?id=6199
http://forums.dropbox.com/topic.php?id=9139
http://www.keepassx.org/forum/viewtopic.php?t=1967&f=1
So hopefully this question will become a suitible resource for people when searching the web.

Feel free to tell me if you think this should rather be a community wiki.