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From: Geoff Dalgas (gdalgas, idcomm dot com) Date: 2001.03.08 - 16.48 MST
X-Mailer: Microsoft Outlook Express 5.50.4133.2400 Then you must also worry about what type of modem: V.34 V.32, etc. If it is a fairly modern modem it would be using V.34 http://www.comm.toronto.edu/~karen/projects/38.ITUV34/ This link describes V.34 in terms of how it works. I'm slowly running out of steam! Is it Friday yet? Geoff > ----- Original Message ----- > From: "Michael Dwyer" <mdwyer, timestreamtech dot com> > To: <mod-chal, cryptofreak dot org> > Sent: Thursday, March 08, 2001 4:38 PM > Subject: Re: Not much progress here.. > > > > Damnit, man, I'm at WORK right now! Why couldn't you send me this one > > on a weekend or something... well, not this weekend... Anyway... > > > > --- Jay Miller <jnmiller, cryptofreak dot org> wrote: > > > Okay, so my original "this is gonna be a piece of cake" idea didn't > > > pan > > > out. The parity bit business isn't working out. Consider the first > > > 20 > > > bits in the thing: > > > > > > 1 1 1 1 0 0 1 1 0 0 1 1 0 1 1 1 0 0 0 1 > > > > Are we sure we've got the keying correct? The bits come out > > significantly different if you consider it to be phase-shift or > > manchester encoding. I need to sit down and stare at it a while, and > > can't do that right now. :( > > > > > Parity just doesn't seem to work on that sucker. And the 'inserting > > > one or zero to break up a BRK' doesn't apply, either.. > > > > Parity is limited to none, even, or odd. That should be relatively > > easy to eyeball... Should be. Do we know that this is a consumer > > modem? Is this assured to be on a phone? With more info, we could > > make assumptions... > > > > For instance, since the frequency doesn't change, it isn't FSK, so it > > isn't a 300-baud modem. PSK looks a bit more reasonable, but it should > > be noted that PSK encodes 2 bits per transition, so we could be reading > > it all wrong. They could be using Manchester encoding, but I've never > > heard of that being used in modem technology, so I would doubt it. > > > > Consumer modems generally run [n|o|e][8|7][1|1.5|2], and that should be > > easy to clock out, right? <sigh> Modems are asynchronous, so there > > should be some form of clocking in the signal, too -- if not the stop > > bits. > > > > I really have to look at my notes, so I'm mostly just spewing ideas for > > the rest of you. Good luck. > > > > > I was also thinking that any encryption would, it seems to me, have > > > to be applied to letters rather than bits.. so we shouldn't have to > > > worry about that. Right? > > > > Our first step need to be finding a reasonably bitstream. The > > encryption is an entirely different problem. That said, I cannot > > imagine the prof being THAT evil -- I'm looking forward to PigLatin or > > ROT13. :) > > > > More later... > > > > > > __________________________________________________ > > Do You Yahoo!? > > Get email at your own domain with Yahoo! Mail. > > http://personal.mail.yahoo.com/ > > -- > > This is the mod-chal mailing list. To unsubscribe, email > > majordomo, cryptofreak dot org with message body 'unsubscribe mod-chal'. > > Or, for more information, visit http://www.cryptofreak.org/. > > > > > -- This is the mod-chal mailing list. To unsubscribe, email majordomo, cryptofreak dot org with message body 'unsubscribe mod-chal'. Or, for more information, visit http://www.cryptofreak.org/.
This archive was generated by hypermail 2b30 : 2001.09.26 - 14.03 MDT |
