Brute force 7z password testing [closed]

Question

I've made a typo in my password back in the days when 7-zip didn't have a 'confirm pwd' field. So now I have a pwd-protected 7-zip file. I've writen some software to generate most likely typo variations of my password (55 million) and stored those in a file per 25k. Now I'm trying them out, one-by-one. I can do about 25k pwd's in an hour, using the unar commandline tool on a Macbook.

It works, but it will still take a nice 100 days (24/7) to go through all 55 mln pwds. Now I'd like to know, if there's some library (c# mono/dotnet) that supports decoding a 7z file that is pwd protected?

Any other suggestions on fixing my problem are also welcome.

Gratian

This might help: https://mcmap.net/q/131478/-how-do-i-create-7-zip-archives-with-net – Swage

Throw it on Azure or any other cloud computing service, and hope it will solve your problem before free trial expires. – Lanner

What @Swage said. Any of those look like they'd work to integrate into your app, and you could use PLINQ to parallelize it as much as possible. – Mimi

@ken2k: SevenZipSharp might have something for me, thx... Will have to find a WinXX machine though... – Gratian

Answer 1

To speed up the brute force, look into using CUDA or OpenCL. These will let you utilise the GPU of the host machine to perform your processing, and will produce results much faster.

25K passwords per hour is quite low - when hash cracking (for example), a good tool using GPU will be able to hit 9500million passwords a minute on a mid-high end GPU.

Whilst hitting that figure is unlikely when trying to break 7z, you could definitely see a speed increase.

Also - the better the PC, the better the result. In many cases a Linux box is your best bet. If you can use a cluster of computers - all the better.

Tayler

Thx for your reply, but this is a project I'd like to complete with the stuff I've got, so no CUDA, OpenCL. I do have a *nix box available so I'll try that one. Also, I'm not hash cracking, or anything, just literally trying 55 mln passwords. – Gratian