February 1993 - cypherpunks-legacy

Re: Modem Based Crypto Telephones
by Phil Karn 08 Feb '93

08 Feb '93

It's true, dialup modems are becoming so fast that low bit rate vocoders may well prove unnecessary for a secure phone with good voice quality. But vocoders are still handy for allowing the use of a slower modem (e.g., over impaired lines, such as those with a lot of taps :-)) and for freeing up bandwidth that you might want to use for other purposes (e.g., data). Phil

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Re: Compressed/Encrypted Voice using Modems
by Phil Karn 08 Feb '93

08 Feb '93

Sounds like we need a new unit that specifically means "bits/sec" but is easier to say. How about "Shannons", as in "I just bought a 14.4 kiloshannon modem". :-) Phil

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Re: Compressed/Encrypted Voice using Modems
by jim＠tadpole.com 08 Feb '93

08 Feb '93

The shannon limit of 22kpbs has something to do with the frequency response of a 'standard' (old, non digital) POTS phone line. But you should know, you're Phil Karn (and I'm not.) Jim

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CLINTON'S E-MAIL HOAX
by John.Nieder＠f33.n125.z1.FIDONET.ORG 08 Feb '93

08 Feb '93

from: john.nieder(a)f33.n125.z1.fidonet.org >The White House writes: > PS: If you did not include your U.S. mail return address in your > message and you want a reply, please send your message again and > include that information. ] Well this is completely useless, isn't it.. If we imagine this ]logically we can see masses of e-mail entering the White House while snail ]mail trickles out... Definately [sic] a buffer problem |-]. At least ]they're trying, I suppose... ]DrZaphod The White House E-Mail gambit is a gimmick without substance. One - according to a previous Cypherpunks post, the e-mail isn't getting through; two - they want mailing addresses for acknowledgement, which is absurd for any number of obvious reasons (take your pick or come up with your own); finally (this is the _real_ kicker), tonight's news informs me that the Clinton White House is making a "symbolic" cost-cutting gesture by reducing staff "up to 25%." Where will these reductions come from? "The reductions will come mostly from staff whose job is to respond to mail from the public." This hoax is the biggest joke since Rush Limbaugh gave out his CompuServe address. A collective Cypherpunk e-letter to Slick? Let's not & say we did...[yawn!] JN ["The White House is informed that no group or persons are authorized by Mr. Nieder to speak on his behalf, including Mr. Clinton."] ... Source: "Deniable Asset Squares Up" - San Francisco, CA --- Blue Wave/Opus v2.12 [NR] -- John Nieder - via FidoNet node 1:125/555 UUCP - ...!uunet!hoptoad!kumr!fidogate!33!John.Nieder INTERNET - John.Nieder(a)f33.n125.z1.FIDONET.ORG

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*Private* E-Mail to White House
by ALAN DORN HETZEL JR 08 Feb '93

08 Feb '93

Maybe we should suggest as a central theme to our first letter that the White House should set up one or more PGP keys of their own. The main purpose being that then one could E-Mail someone in the administration with reasonable certainty that the message could neither be intercepted nor tampered with. Of course, once they get around to responding via e-mail, it works both ways.... Alan Dorn Hetzel, Jr. dorn(a)indigo.mese.com p.s. I'm not wired up with PGP yet because i'm using a VAX running VMS and DECUS UUCP. Has anybody ported PGP to this platform? Ideas?

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No Subject
by root＠extropia.wimsey.com 08 Feb '93

08 Feb '93

Hi - I tried to use the anon.penet.fi remailer and got a warning that some people had hacked it to find out for which anonymous ID any user had. It sounded like they would forge mail from the person they wanted to find out about, have it go through penet, and then go to themselves. Then they could look and see what anonymous ID it seemed to come from. This has been fixed by making people register a password with the remailer and then use it whenever they want to forward mail. I'd like to see some discussion here about this problem so that other remailers can avoid it.

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Remailers (List available)
by uni＠acs.bu.edu 08 Feb '93

08 Feb '93

I was hopeing to find a list of the remailers available that use PGP for traffic encryption. I noticed that the PAX scripts were made public recently, does anyone plan to employ them at any of the current remailing sites? Despite its problems, I thought PAX was on the right track with regard to tactics.... Comments?

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Re: 'Sunday Times' article on GSM changes
by fnordbox!loydb＠cs.utexas.edu 08 Feb '93

08 Feb '93

:(Thug writes) : :> According to what I read it seems that the whole issue of cellular radio :> signal encryption is really a non-issue. They could have the most secure :... :> What makes you think they don't have the same kind of REMOB/BLV capability :> to the cellular telephone switches? I mean, if a conversation is scrambled :... Eric Fogleman writes: : :If getting around GSM encryption is no problem, then why are governments :pushing the issue? This actually hits on one of my favorite rant topics. The feds like to scream about how hard it is to tap a phone line with digital switching et al, but don't talk about the fact that anyone with half a brain can tap a line using the phone company's LMOS. The only rational theory I've come up with to explain this is that the feds aren't worried about court-ordered wiretaps, but about illegal wiretaps. I bet there's a *lot* of monitoring going on out there that they can't get a court order for, so they're doing it themselves. Monitoring without the cooperation of the phone company will get harder when the company starts paying more attention to security -- whether through encryption or simply using a shredder. :-) Loyd *************************************************************************** * loydb(a)fnordbox.UUCP Call the Fnordbox BBS * Loyd Blankenship * * GEnie: SJGAMES 2 v32bis lines, 24 hrs * PO Box 18957 * * Compu$erve: [73407,515] 512/444-2323 * Austin, TX 78760 * * cs.utexas.edu!dogface!fnordbox!loydb * 512/447-7866 * ***************************************************************************

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Re: Compressed/Encrypted Voice using Modems
by Phil Karn 08 Feb '93

08 Feb '93

At 7 Feb 04:56 CST, Jim Thompson wrote: >I don't see how a 28.8kbps (raw) data rate is possible, as the Shannon >limit for a POTS line is 22kbps. Certainly parts of the phone system >no longer impose the narrow bandwidth that are part of the 'spec', but >one can not always depend on getting a line that exceedes the published >parameters of the phone system. Where do you get this figure of 22 kbps? I would tend to dispute it since I use a Codex FAST modem on my SLIP link and it really does run at 24.0 kb/s on the wire (not counting compression). The throughput display often reads 30 kb/s even when I'm shipping a pre-compressed or encrypted binary file, although that's a phony figure because it includes the asynch start/stop bits that aren't actually sent over the wire. The usual Shannon limit of a phone line is more like 30 kb/s, although it can vary enormously. Generalizations are dangerous. At the very least, you can certainly say that it's no greater than 64kb/s, since it's almost certain that your call passes through a mu-law codec somewhere. Back to vocoders, their quality does tend to be a strong function of data rate. 8kb/s CELP is really not that bad - a little warbly when there's background noise, but not objectionably so in my opinion. In a mobile telephone environment (where I'm familiar with it), it's *much* less objectionable than the usual impairments you get from ordinary FM analog transmission. 4kb/s is noticeably worse. Things get rapidly better as you go above 10-12 kb/s with present algorithms. Also, vocoders need not be constant rate. Ours selects one of four rates on the fly depending on voice activity, which doubles capacity in a CDMA radio environment. It'd also be useful in a packet network, although the small frame sizes (2/5/10/22 bytes) can make header overhead rather significant.

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Re: Compressed/Encrypted Voice using Modems
by jim＠tadpole.com 08 Feb '93

08 Feb '93

> From: Peter Shipley <shipley(a)tfs.COM> > >And why are you limiting this to V.32 (9600bps)? V.32bis (14.4k bps) modem > >chips cost maybe 20% more than v.32 chips in quantity. > > at Interopt I heard some voice demos that were at 9600 4800 and 2400 baud > the 2400 sounded a phoneme chip but was *very* resionable. Quite likely what you heard were 9600/4800/2400bps (bits per second), not baud. The two are different. 2400bps compression of voice is quite a bit beyond current GP CPUs. Also, note that 9600 baud (V.32 carriers) are based on a 2400bps carrier. (And if they're not, I'm sure someone will correct me.) 2400 baud modems are based a bit rate something less than 2400bps, though I can't remember exactly what it is right now. Jim

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