cryptofreak.org cryptofreak home projects
contact about
mod-chal
NewsNews
Contact: ledge


projects
Antera Antera
Commentator Commentator
Feast Tracker Feast Tracker
News Frotz
gkrellmGIMPS gkrellmGIMPS
Holy Librams! Holy Librams!
Linux Porting Linux Porting
minihuff minihuff
mod-chal mod-chal
Recipe Radar Recipe Radar
RFC 3394 RFC 3394
Riggy Riggy
Contact: webmaster


  A New Crypto Challenge!

Earlier today I was introduced to the crypto challenge that is talked about below. It originates from a CU professor (whose name I know not), and we have VERY LITTLE TIME to solve it! There's not exactly any prize for solving it (ahem), but I'm hoping when you see the code, you'll be as intrigued as I am.

Challenge Information 3.12.2001 10:55 pm -- ledge News

You can find the document that contains the original code here. Neat, huh? (And Matt, don't go asking me to HTMLize this mutha.. if you want another format, here it is in postscript!)

So this code is an extra-credit problem for a graduate level information-systems class at CU. Here's some of my initial thoughts:

  • It's an IS class, so I don't think it'll be *too* tough. If you check the class web site from which this sucker came, you'll see that during the course of the course, one of the topics is 'bits and bytes'. So it may not be TOO advanced. Here's the description from the CU Course Listing:

       INFS 5030. Computer Network Design and Management. Focuses on the backbone of an organization's information infrastructure that ties various kinds of computers together into a coherent whole. Introduces the component building blocks of network design such as servers, routers, bridges, gateways, transmission media, communication protocols, network operating systems, and middleware. Covers local area networks in some depth and introduces metropolitan and wide-area networks. Also covers data compression, encryption, network security, and performance tuning.

    Alright, so it's not an easy course, but there can't be too much focus on encryption.

  • It looks like it has been modulated with a technique called 'phase modulation'. It is also called 'phase shift keying' or 'PSK'. This method uses changes in phase to indicate digital bits. We've found the following references on this sort of thing:

    • This is short intro-type thing with fair diagrams - has info on PSK and async transmissions.
    • This is a good paper generally on modem communication. Talks about async/sync methods, and PSK.
    • This is an excellent encyclopedia of radio communications. Search down for 'phase' - it shows how waves translate to bits. (big)
    • This is a section from a network book on modulation.
    • This is the WinPSK reference manual. It has information on PSK, synchronous communication and 'varicode' characters' binary values.
    • This is a primer on async modem communication from Microsoft. It talks about the differences between sync and async communication.

  • So, with all that we should be able to demod the picture to binary. Unfortunately, there could be a couple of ways to do this. Here's a couple of pages on the different methods of PSK that we're concerned with (I think):


mod-chal CVS Repository Access 3.10.2001 1:44 am -- ledge CVS

Since there was at least some desire for it, I went ahead and set up what is for now a read-only CVS repository (I only have so much time to do stupid shit like this!) for the challenge and any tools we might wanna write and distribute. If there's some stuff you've written and would like to hand out, feel free to email it to me and I'll put it up there. (Write access will come later when I have a chance to setup some security or something.)

mod-chal Mailing List 3.8.2001 1:55 am -- ledge Mail

If you've actually made it down to the bottom of this page, it shows you at least have some interest in this strange thing I've gotten myself into. The next step is to join the mod-chal list I have setup. (That's right, you can't crack it just yet. Dave, Ben - I'm talking to you!) Head over to the mailing list page for further instruction!