John Graham-Cumming posts about cracking an old ZIP file to help open source the ANC’s “Operation Vula” secret crypto code.

It’s not often that you find yourself staring at code that few people have ever seen, code that was an important part in bringing down the apartheid system in South Africa, and code that was used for secure communication using one-time pads smuggled into South Africa by a flight attendant on floppy disks. But I found myself doing that one morning recently after having helped decrypt a 30 year old PKZIP file whose password had long been forgotten.

Tim Jenkin, the person primarily responsible for the encryption system, has now open sourced the original code, and which can be found here. Tim’s write up on the encryption system can be found here.

Tim writes:

I still have the Vula source code but unfortunately most of it I can’t access because when I left the UK in 1991 to return to South Africa, I zipped up all the files with a password. I was able to decode and extract one of the files but it was a very early version of the software. The rest I couldn’t extract because I forgot the password. When I got back to SA there was no need to access the code. I thought I would never forget the password but when I tried to decode it a few years later, I couldn’t remember it.

So John goes digging into the ZIP file and seeing it’s an older version, notes there are “cracks” of the encryption if you know other data like the filename(s) inside the archive. With an idea of the names, the “bkcrack” program was able to extract the files in 20 to 25 minutes.

See the whole story in the post here.