February 1993 - cypherpunks-legacy@lists.ogf.org

Re: Compressed/Encrypted Voice using Modems
by Phiber Optik 09 Feb '93

09 Feb '93

> > haven't seen it. > OK, fearing the worst (maybe I forgot to CC my message to cypherpunks, but I'm sure I did), I'll repost my original message. It was a God-sent that I got cut off last night while composing it, and expreserve preserved it. Here it is: > > > ... because in FSK systems which code 1 bit per symbol > > (only two phases), bps = baud. But then and ONLY then.... > > Uhh, don't you mean two frequencies? FSK is Frequency Shift Key, not > Phase Shift Key (PSK).. ;-) > > Actually, I KNOW you meant this, and it was probably just a typo, > right? > > -derek > Woops! Sorry. To compensate, I'll give more information. In the Bell 103 system (FSK), the frequencies are 2125Hz for answer, and 1170Hz for originate carriers, with the frequency shifts being +/- 100Hz. Compare with CCITT's V.21, and substitute the carrier frequencies with 1750 and 1080Hz. Same +/- 100Hz shifting. Someone else mentioned the almighty Claude Shannon in another message concern- ing maximum bit-rate of a voice channel, and I wanted to clear up what was said. Shannon's capacity formula said capacity in bits-per-second equals bandwidth of channel in hertz times the base-2 (binary) logarithm of one plus the signal (in watts) to noise (in watts) ratio. As a side note, I say watts because commonly, today, you measure signal and noise levels in decibels (dB), and the S/N ratio is in dBm's (decibels per milliwatt). In the phone system, we say a voice frequency channel (VFC) has a bandwidth of 4kHz. In-band signalling is approximately from .3 to 3kHz. This formula (yielding the Shannon limit) is based on a "Gaussian Band Limited Channel" (GBLC), which is an approximation of a VFC, with a signal wave of S watts at the input of an "ideal" low-pass filter, subjected to Gaussian noise with a mean power of N watts (uniformly). Written, it's C = W log2(1 + S/N). A simple example you can do in your head is W=3000Hz, pick an S/N of 1023, 1+1023 is 1024, and base-2 log of 1024 is simply 10, 3000 * 10 is 30000, so Shannon's limit for these values is C = 30000bps. Play with it. Bear in mind, Shannon didn't consider intersymbol interference. Nyquist did. Compare this to Harry Nyquist's 2-bit rule, 2W, or double the bandwidth, and get the maximum bit rate (this line of thinking led him to the infamous Nyquist sampling theorem, sample at a rate twice the bandwidth of a channel, and you have all the information you need to reconstruct it at the receiving end). But Nyquist deals only with binary systems. Shannon's formula shows that theoretically you could increase the data rate indefinitely by increasing the S/N ratio. We achieve this in modern modulation systems by using multilevel systems, (M-ary for short, with M > 2), and hence the protocols I described in my previous message. We can apply Nyquist's 2-bit rule to the multilevel system by saying 2W log2 M bps is achievable, with an acceptable error rate. As we increase M (number of bits per symbol), so we have to find ways to increase the signal to noise ratio, to maintain an acceptable error rate. The whole thing is stupendously interesting to me, as I hope it is to the rest of you folks. To blow your mind with sheer genius, read Shannon's classic "A Mathematical Theory of Communication" in Bell System Tech Journal, July and October of '48 at your local university. Also Nyquist's "Certain Topics in Telegraph Transmission Theory", April '28. Know your roots. Good night.

2 1

Re: Compressed/Encrypted Voice using Modems
by Phil Karn 09 Feb '93

09 Feb '93

>Shannon didn't consider intersymbol interference. Sure he did. That's why the bandwidth term appears in his channel capacity equation. Shannon built on and generalized Nyquist's earlier work. Shannon's law says only that it is theoretically *possible* to signal over a bandlimited AGWN channel with specific bandwidth and S/N ratio with arbitrarily low error as long as the signalling speed is less than the channel capacity as given by his formula. What it doesn't show is *how* to do it. In this respect, Shannon's law is much like the 2nd law of thermodynamics; it tells you how efficient you can make a heat engine in theory, but it doesn't tell a turbine designer how to shape his blades. By the way, just to bring this back to crypto, everyone should be aware that not only did Claude Shannon establish modern information theory, he also wrote a seminal paper that established much of modern cryptography. It was originally written during WWII and classified at that time, but it was declassified soon after the war and appeared in the BSTJ in 1948, I believe. Probably the most well known aspect of this paper is his discussion of "product ciphers", whereby you can combine different ciphers that are by themselves relatively weak (substitution and permutation, which he calls "confusion" and "diffusion") and produce a far more powerful cipher. DES is based on this principle, as are other modern ciphers. I bet this is one paper that the NSA wishes had never been declassified. Far more important, in my opinion, than anything by Friedman. Phil

3 2

E Pluribus Unum
by deltorto＠aol.com 09 Feb '93

09 Feb '93

Fellow Cyphers, Eric Hughes contributed: >>I applaud the Clinton administration for making itself available via >>email. I do not think it advisable, however, to send a single >>cypherpunks letter. Rather I urge all interested parties to compose >>their own letters, and send them in separately. and also: >>3) Be brief. If you cannot summarize your argument into a single >>paragraph, neither will the reader of the mail. The mail system is >>already overloaded, and concision indicates politeness. These appear to be contradictory statements. I believe that sending a powerful concise letter _together_ makes it more likely that it will be read, and even more likely that it will be responded to. Otherwise, we're just a bunch of nutty "individuals." On the other hand I am repenting my suggestion that we _might_ include anything political in our missive. This was ill-concieved on my part and I have now "engaged my brain" (it's also not 4 am, heh-heh) and agree with various other contributors that our message should be unidirectional and very brief. I don't think it should be "cutesy" however, as much as I personally enjoyed Marc Ringuette's "bit" suggestion #2: >>Dear President Clinton, >> Freedom for the bits! We will not rest until each bit is free to >> determine its own natural orientation without outside coercion. The >> good news is, you don't need to do anything at all; merely get out of >> the way of the free market, and the bits will free themselves. >>Best regards, The Cypherpunks (Anarchist Subgroup). Basically I like the underlying idea here (the track of allowing 'natural orientation without outside coercion'), but I'd avoid the "anarchist" tendencies, as they tend to render an otherwise approcahable letter "void" for government bureaucrats perusing gigs of email to Bill & Co. Eric suggests that we: >>Stress privacy, and technological defenses thereto. I agree. Especially the technological expertise side, as this is what differentiates us from the mass of other people crying about privacy. >>2) Do not be paranoid. Do not rant. These are a sure ways to >>indicate that more money should be budgeted for public relations. This is well-met. I totally back off from my previous political slant in favor of getting _through_. >>4) Write in standard English. Use a spelling checker, and use >>complete sentences. What a concept. After reading a few months worth of mail on this list, I can only agree. >>5) Offer to help. Offer to make timely review of proposed policies. >>If they accept your aid, keep your promises. This is my favorite suggestion. Imagine if they gave us all jobs at the NSA. Heh-heh-heh. Now, I have a general question: what is the current status of the White House email capability as far as everyone can tell? Has anyone had a response yet, by email or snailmail? Is there a possibility that this IS a hoax and that we should just send paper mail instead? ddt

2 1

Debate about anon posts
by Hal 09 Feb '93

09 Feb '93

For those interested, there has been an active debate on the Usenet newsgroup news.admin.policy about whether anonymous posting should be allowed on technical newsgroups. Johan Helsingius's anonymous server at anon.penet.fi is being widely attacked for allowing this function. Several questionable messages have been posted to various groups using this server and some of these are being used as examples of why anonymous posting should not be allowed. There have been about 50 messages on the topic, with probably 40+ being generally opposed to anonymous posting on the non-"personal" groups, and only a few being in favor. I don't really know how much influence that newsgroup has on the Usenet anarchy but there certainly does seem to be a lot of opposition to anonymity. Since it is an important part of our Cypherpunk ideals I think we need to give some thought to how to "sell" the idea of anonymous mail and postings to the net community. Hal Finney 74076.1041(a)compuserve.com

2 1

Re: E Pluribus Unum
by covin＠cs.uchicago.edu 09 Feb '93

09 Feb '93

>Now, I have a general question: what is the current status of the White House >email capability as far as everyone can tell? Has anyone had a response yet, >by email or snailmail? Is there a possibility that this IS a hoax and that we >should just send paper mail instead? What excellent timing you have. I recently received this from a friend: [Forwarded, now several times...] January 31, 1993 Important Information RE: E-Mail to the White House Yesterday, I saw several postings related to the E-mail address for the White House. Along with a good number of others, I worked throughout the campaign as part of a network of E-mail volunteers for the Clinton campaign, so I can pass along some important information about that E-mail account. The account is actually the personal compuserve account of Jock Gill. Jock worked hard (along with a handful of programming volunteers, BBS operators, listserver maintainers, and computer sophisticates at places such as Marist College, MIT, San Francisco, Chicago, and elsewhere) during the campaign to put together an E-mail system for national campaigning. The system was later expanded to accommodate all three major Presidential campaigns. It was an innovative, highly successful effort and it played a huge role in getting campaign position statements out to a wide public. Things posted from that address found their way into the virtual reality as the messages got passed along many networks from their original posting. Several weeks before the Inauguration of President Clinton, Jeff Eller was appointed by the President-Elect to have overall charge of establishing something which has never existed--an interactive public access E-mail system into the White House and into other offices of the administration. Jock Gill was then hired by the administration to work under Jeff Eller. Currently, Jock Gill is working in an office located in the Old Executive Office Building across the street from the White House. At this point, he is working alone, without a staff. His current assignment is to use the E-mail system (as during the campaign) to issue official copies of White House statements, the texts of press briefings and press conferences, copies of Executive Orders and Presidential Memos, and the like to the virtual world of E-mail. Since the compuserve box is a regular personal mail box, it gets filled quickly, especially given the high volume of mail now beginning to arrive with the broad dissemination of his address. Those of you who have sent E-mail to that address may well have received an error message stating that the box is full. That's another way of saying it has been overwhelmed. Jock has asked those of us who have been part of the volunteer E-mail team to help him out while he works to get a good interactive system up and running. Basically, he has asked that everyone cooperate and not begin sending a barrage of E-mail to that compuserve address. The White House itself employs a large staff to handle snail mail. Actually, at this point in the development of the White House E-mail system, you will probably get your message through to the administration quicker through ordinary snail mail and telephone. Later, once the administration's E-mail team develops the system they want and need, E-mail contacts should became the easier route. All things in their time. Once the E-mail address was circulated together with the heading the "White House", everyone understandably believed a real system was up and running. Not quite yet. SUGGESTION: Use the compuserve address you have judiciously, reserving it for absolutely vital contacts. Until such time that a real public access White house E-mail system is operational, consider relying on the traditional means of contacting the administration. Given what they had to start with from the previous administration (scratch), I have every reason to expect that Jeff Eller and Jock Gill will work well--and as quickly as possible--to get an interactive system up and running. But it will take time and patience. We can all help them achieve that effort best if we refrain from acting as if that non-existent system were already in place. PLEASE HELP RELAY THIS CONTEXT AND SUGGESTION TO OTHER NETWORKS AND INDIVIDUALS. Thanks. Snail Mail Address and Phone Numbers -- White House White House Numbers: The President (202) 456-1414 White House Comment Line (202) 456-1111 (To register your opinion on an issue) When bill signed or vetoed (202) 456-2226 Vice President (202) 456-2326 (202) 456-7125 Mailing Address: The White House 1600 Pennsylvania Avenue, N.W. Washington DC 20500 ------ Jon Darling PITT/Johnstown -- January 31,

1 0

Convincing people the value of anonymity...
by wayner＠cs.cornell.edu 09 Feb '93

09 Feb '93

I would think that many people who hang out on technical newsgroups would be very familiar with the anonymous review procedures practiced by academic journals. There is some value when a reviewer can speak their mind about a paper without worry of revenge. Of course everyone assures me that the system is never really anonymous because there are alwys only three or four people qualified to review each paper. :-) Perhaps we should go out of our way to make anonymous, technical comments about papers and ideas in the newsgroups to fascilitate the development of an anonymous commenting culture in cypberspace. -Peter Wayner

1 0

Anonymous pool created
by miron＠extropia.wimsey.com 09 Feb '93

09 Feb '93

-----BEGIN PGP SIGNED MESSAGE----- From: miron (Miron Cuperman) To: cypherpunks(a)toad.com Subject: Anonymous pool created The pool is basically a mailing list with automatic maintenance. The intention is that you add a reply-to: header to your anonymous mail (or mention it somewhere in your mail) pointing at the pool address. Make sure that your correspondent put some identifying marks on the reply (like encrypting it with your public key, and/or putting your pseudonym on the Subject: line) so you can tell it apart from the rest. Of course, you should first subscribe to the pool. Your anonymous reply address you should mention is: pool0(a)extropia.wimsey.com All admin requests (handled by a program): pool0-request(a)extropia.wimsey.com All problems to: miron(a)extropia.wimsey.com The following Subject: lines are recognized: subscribe unsubscribe help and others - described in the help file. Matching is actually quite loose, so don't worry about whitespace or anything like that. Experiments are welcome. - -- Miron Cuperman <miron(a)extropia.wimsey.com> | NeXTmail/Mime ok <miron(a)cs.sfu.ca> | Public key avail AMIX: MCuperman | cyberspacecomputingcryptoimmortalitynetworkslaissezfaire -----BEGIN PGP SIGNATURE----- Version: 2.1 iQCVAgUBK3eLOZNxvvA36ONDAQEjfAP+LqMzz6ffgTcuVxnzivZKKAJHY7kzo6V2 cobwO4fWPOdw6m3TdJnX/++hit0nAiFOg5TZWMqJiUw/p51qcPIHxXvsw0Hq9mN5 y8eKoZDVVuALZD3IRzAbWuZ9gT404q5sUej7T8k/Ykf51fIMy29JXxAl00sXvRzi mI0NNzykWSc= =J84n -----END PGP SIGNATURE-----

1 0

Re: Compressed/Encrypted Voice using Modems
by Phiber Optik 09 Feb '93

09 Feb '93

> > So, what is a 'typical' S/N ratio for a POTS call? > > Good question. By the way, I think I may have slipped and reversed my units in signal to noise ratios. A minor typo. The signal and noise are in dBm's (decibels per milliwatt), and the resultant S/N ratio is in dB's (decibels). A little background info: the ideal voice frequency channel has a FLAT amplitude/frequency response, that is, it's uniform over the pass-band (approx. .3 to 3kHz). In reality, this isn't the case, but we want it to be as close as possible. In North America, we test signal level at 1kHz (precisely 1004). If we input a signal at -10dBm, we want -10dBm at the output. The common type of test-line in the phone system for this purpose is nicknamed the "milliwatt test", and is a continuous interrupted 1004Hz tone. Depending on the nature of the channel being tested, there would be acceptable guidelines that would have to be met with. For example, a typical S/N value might be 40dB, based on customer satisfaction of line quality. Another common test-line in wide use is the type-105 ATMS, Automatic Trans- mission Measurement System (nicknamed "responders"). Signalled with Multi- Frequency tones (MF), it is capable of doing: signal at 404, 1004, and 2804Hz at two different levels (for comparative S/N ratios at the low, middle, and top portion of the passband, a major improvement on the older "sweep tone" method), and two types of noise (again I remember at two levels), the most common being C-message noise (dBrnC). C-message weighting is the modern means of measuring signal and noise amplitude/frequency response, based on today's telephone handsets (there were two previous major Western Electric weightings, 144 and F1A, now obsoleted). The standard reference frequency (1004Hz), was established by picking a frequency in the pass-band where the signal level was JUST discernible by the human ear, and is between -85 to -90dBm, and the derived units are positive. We consider the noise measurement knowing the zero reference (ideally 0 dB difference at the reference frequency), and the weighting characteristics of the C-message standard telephone handset. Unfortunately, I can't draw you a chart, but there is a characteristic curve of frequency-response in weightings of channel noise for the C-message handset. Noise measurement instruments have artificial filters that simulate the response of the modern handset. Am I making any sense? I hope I am. What I'm getting at, is that the accept- able guidelines of signal and noise levels is simply based upon a chosen standard handset sensitivity. Got it? C'mon! It's easy!

1 0

Re: SunExpress to expand "unlockable" software distribution
by fnerd＠smds.com 09 Feb '93

09 Feb '93

gnu(a)toad.com (John Gilmore) says: >It would probably be a public service if some interested parties were >to determine the ``encryption'' method that Sun Express, the standard >Sun ``license manager'', and other packages use. At the moment, the >details of these technologies are not described in the public >literature (as far as I know). > >Rather than have these companies discover years too late that their >"unlockable" software is really unlockable by anyone who understands >cryptography, it'd be better for them to learn it this year, while >they are still handling low volumes of programs that way. Also maybe >they will stop dumping these programs-that-you-have-but-must-pay-to-run on us. > > John I was in a meeting where the license manager technology was explained from a semi-technical, semi-business point of view. o There's a standard that many companies are using. It's for the rpc interface between licensed programs and license managers. The program calls the manager, tells it a couple things, and asks, is it okay for me to run? o License managers vary in the kinds of licenses they can support. There's enough variety of license possibilities to make your head swim. o License managers generally work from "licenses," which are text files on your computer that describe the terms of particular licenses in a license-manager-specific language. o I think they use RSA, MD5, etc., for instance in signing logs that they keep. o License-managers are themselves expensive and licensed, with a variety of up-front/per platform/per site/per end user/per developer license combinations as well as the feature variety I mentioned. I could probably find out what public documents exist if nobody else on the list knows. -fnerd quote me fnerd(a)smds.com (FutureNerd Steve Witham)

1 0

White House Mail
by Don Henson 09 Feb '93

09 Feb '93

Can someone repost the email address for the White House. I seem to have misplaced my copy. :( Don Henson PGP key on request

2 1