Blowfish encryption

I have an app that was written in VB6 then compiled to what appears to be native code then it was packed with a version of UPX (probally old version) the new versions of UPX will not un-pack, but I managed to un-pack the program with a PE Editor....

now after inspecting the headder I find the unpacked program has a Blowfish encryption signature ... since I do not know the original password I cannot de-crypt with Blowfish program.


the unpacked program runs fine just as it did before I un-packed it, so I am making head way ..

can anyone toss me a bone about Blowfish .. I have been to the author's site and studied the program and I think source is available for blowfish but not sure that will help.

Well, I would suggest getting the source code to Blowfish so you can identify the functions inside your target. Whether you can crack the app or not depends entirely on how the Blowfish encryption is used. Say for instance the serial number you enter is the key to the encryption, then you're screwed. But if it's like most programs that use it, then they will be using Blowfish to encrypt/decrypt the serial with a hardcoded key. And as you can imagine, it's a piece of cake from there!

I'm not trying to crack this program, it's wide open already...

what my goal is .. is to update some of the menu feilds, the author of the program is no longer supporting it any more and the program is freeware to begin with, so I was just reversing it so I could make my own modifications..


I haven't been able to identify what if anything is actually encrypted ... it may only be a few modules within the progie that are encrypted.


I believe that it uses a separate private key on a floppy, the public key is probally internal to the program for it's own operation