How to decrypt Blowfish in AIR?

kupo_games

Hey guys, I'm updating an old Windows Flash app that was previously launched via a now defunct wrapper called MDM Zinc. It created text files that were encrypted with the Blowfish algorithm. I'm now trying to decrypt these files with Adobe AIR, so that new versions of the app can still open the old encrypted files - what's the best way to do this?

I found a library that seems to do the job, called "as3crypto", but web pages with examples seem to not exist any more, so I don't know how to use it.

Thanks for any advice.

joshtynjala

The source package for as3crypto includes a CryptoDemo.mxml app that can be compiled with the Flex SDK. The SecretTab.mxml file seems to demonstrate how to use a number of encryption types, including Blowfish. They're all mixed in together in the same file, though, so there isn't a simple demo of Blowfish only that's easy to copy and paste.

I searched for as3crypto blowfish on Google, and I saw a number of questions with answers on Stack Overflow, like this one (and there were more):

https://stackoverflow.com/questions/6977595/errors-decrypting-as3crypto-blowfish-data-in-php

Maybe looking over multiple examples like the ones in the answers there will help you work through it.

kupo_games

joshtynjala

Thanks! It turns out the problem was that I had my input in the wrong format. I gradually figured that out by working through all the examples that I could find, but in the end the example at the very bottom of your link was pretty much what I needed.

I've managed to decrypt my files now, but a little bit of the start of the file is cut off, so I assume this is some padding issue that I now need to figure out. But I'm making some progress!

Edit: The issue seems to be that the first 8 characters of the output are missing. I wonder what I've done wrong...
Edit2: When I supplied an empty InputVector, it started to work correctly!