August 1993 - cypherpunks-legacy

ANONYMOUS CONTACT SERVICE
by hfinney＠shell.portal.com 12 Aug '93

12 Aug '93

From: Warren Keith Russell <keru(a)cpu.us.dynix.com> > I received a message from System Daemon telling me that I had sent a > message using the anonymous contact service, allocating a code name, and > explaining how I can be reached anonymously. A few months ago, someone subscribed to the list through the Penet service, and it ended up revealing the Penet aliases of everyone who posted. Each post was delivered to that subscriber marked as being from the Penet alias corresponding to the poster. All it took was a parallel non-Penet subscription to break the anonymity provided by Penet. Has this now happened again? At the time, there was some discussion about using "an..." versus "na..." forms of the Penet aliases, one of which would avoid this revelation. Has that been taken care of? Hal Finney hfinney(a)shell.portal.com

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Re: Secure voice software issues
by jthomas＠kolanut.mitre.org 12 Aug '93

12 Aug '93

Phil Karn <karn(a)qualcomm.com> wrote: [Re: squeezing 13.3 kbps data w/o start&stop bits over modem] > Whenever V.42 error correction (LAPM) is enabled, > synchronous HDLC frames are what actually pass over the > link. So the start/stop bits are already removed. > Unfortunately, the packetizing done by LAPM adds delay > we don't want for a real time voice application. And if you > turn off LAPM, you return to sending the start/stop bits > over the wire. Well... How much latency does LAPM really add? Little enough that full duplex keystrokes echo back nearly instantly on my connections. People talk over satellite links with more delay than that all the time. Since we're not going to get toll quality voice out of the vocoders anyway, and the error correcting stuff is especially useful for encrypted data streams... I think V.42 is probably a good idea for a cryptophone project. > Most V.32 and V.32bis modems provide for direct > synchronous operation, which would let us have our cake > and eat it too, except that few PCs can speak > synchronously to a modem. This may require some extra > hardware (sigh). I'm in favor of getting a minimal version that will run on the lowest common denominator hardware first. (Might have something to do with the fact that I just spent a couple hundred dollars on an internal V.32bis modem that doesn't do synchronous :^) Joe

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Cryptographic File System paper available for ftp.
by mab＠vax135.att.com 12 Aug '93

12 Aug '93

Hi, A PostScript pre-print of the final version of my paper "A Cryptographic File System for Unix" is available for anonymous ftp from research.att.com in the file dist/mab/cfs.ps . The paper will be presented at the 1st ACM Conference on Communications and Computing Security, November 3-5, Fairfax, VA. A number of people on this list have seen an early draft; this is the final version. Some of the techniques in the paper may be of general interest to people contemplating file system-level encryption in other systems (e.g., the cryptostacker project). -matt

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Making the World Safe for Steganography
by tcmay＠netcom.com 12 Aug '93

12 Aug '93

How do we make steganography safer to use? An anonymous comentator wrote about my point (in the essay "Libertaria in Cyberspace"), and then Eric Hughes responded: >>Alice better not be carrying any software that could retrieve that >>data. > >Q: What do you call a store that sells 'cryptographic paraphernilia?' > >A: A mind shop. > >If crypto is outlawed, then random numbers will be probable cause for >search for illegal cryptographic devices, software or hardware. > >Q: What is a random number? > >A: Anything I don't understand. With steganographic (data-hiding) schemes, how is the "unhiding" scheme to be stored? If the user has a diskette labelled "Steganography" sitting prominently near his computer, for example, and this diskette has just a single algorithm on it--perhaps for stripping the LSBs out of GIFs--then it is fairly obvious which algorithm is being used, and that steganography is in fact being used in the first place. (However, what comes out of the de-stegging, to coin a phrase, should still be meaningless without the actual decryption, so I'm not sure what the authorities can or will try to do. During wartime, or in many countries, I'm sure that possessing such steganographic software would be a serious matter, but the U.S. has not (yet) reached this point. And there's enough bits to play with on a DAT to make the data bits look almost exactly like audio/microphone noise, with the same statistics, spectrum, etc.) One good way to further confuse the issue is to make certain steganographic schemes *widely available* by wide distribution on CD-ROMs (to ensure that nearly everyone can feign innocense when the Data Patrol asks them some questions) or by easy access by ftp-type approaches (though this has limits which are discussed later). In other words, there is no obvious "smoking gun" pointing to the use of steganography. Or encryption, for that matter, as PGP-like crypto programs could be similary distributed, someday, and only the secret key/passphrase would be "incriminating" to the user. I'll leave it for another time to discuss ways to hide the secret key/passphrase (perhaps in things like Newton PDAs which implement "digital flash paper" in their flash memories, or are carried with the person at all times, etc.). A Cypherpunks CD-ROM? Perhaps the Cypherpunks could someday even make such a CD-ROM widely available, along with rants, source code, whatever. (*Very* speculatively, someday "Wired" may even distribute a CD-ROM in one of their issues.) Remember, the point about steganography schemes, like hiding message bits in the LSBs of music tapes or images, is *not* to make the bits "undetectable," but only to hide them sufficiently to make a case for "plausible deniability." Thus, if the Data Patrol uses "Algorithm A6" (one of many on the CD-ROM) on a DAT you are carrying, and the sequence "1 0 1 1 1 0 1 0 ...." emerges, you just shrug and claim ignorance. "Sounds like noise to me." However, when the Patrol is not around, you apply, say, "Algorithm Z1" to the DAT and then use your private key to decrypt the bits. (How you secure your private key is another issue, of course, as mentioned above.) Some may quibble that this is a kind of low-level encryption...after all, the CD-ROM may contain only a few dozen algorithms for stripping bits out of DATs and images, so the NSA or FBI can simply apply them all, trivially. This method would indeed be low-level (nonexistent, actually) security if the resulting bits were a plaintext message. But the resulting bits are in fact meaningless noise without the private key. I suspect that such wide distribution of steganographic schemes will be enough to ensure that users can safely retrieve "their" bits (using one of the algorithms) without the authorities being able to prove anything. If this analysis is correct, then getting various steganographic schemes out in the public domain is important. Executable code--to allow users to run the programs right off the CD-ROM and thus not have the code copied (incriminatingly) to their hard disks--would be best. This code could be tucked away in a small part of CD-ROMs. What I envision is a CD-ROM (or whatever other distribution modes are popular) containing this steganogrophic and cryptographic software and lots of other stuff, in other domains. That is, the crypto/stego part could just be a tiny fraction of this "Hackers Disc." Speculatively, we could do this ourselves, or work with "Wired," EFF, the Gnu folks, etc., to get these programs tucked in someplace amongst their files. (There are issues of platform compatitibility, which systems can read which CD-ROMs, etc. Details.) Making the algorithms available by ftp is of course already common practice. The reason I don't emphasize this is that users must download the programs to their systems, thus decreasing plausible deniability. (However, if the programs are just part of a larger collection of files, like a "News Magazine" of a bunch of files, then these algorithms will be just some of the _many_ files downloaded, and the user can once again feign ignorance. This would be a kind of "stego stego," where the stegonographic algorithms are themselves hidden amongst a bunch of unrelated files.) I realize all this may be too complicated, that the stego programs themselves are barely starting to appear (I know of a couple of efforts going on), and that the problem of how to claim ignorance may not be important for a few years yet, if ever. On the other hand, there may be value in getting these stego schemes distributed long in advance of their being needed. Comments? -Tim May -- Timothy C. May | Crypto Anarchy: encryption, digital money, tcmay(a)netcom.com | anonymous networks, digital pseudonyms, zero 408-688-5409 | knowledge, reputations, information markets, W.A.S.T.E.: Aptos, CA | black markets, collapse of governments. Higher Power: 2^756839 | Public Key: by arrangement Note: I put time and money into writing this posting. I hope you enjoy it.

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Cypherpunk FTP site -- where is it?
by ferguson＠fiber.sprintlink.net 12 Aug '93

12 Aug '93

Could I entice someone to remind me of where the anon FTP site (and directory) is located? I seem to recall that it was on soda.berkeley.edu but beyond that, my memory fails me....

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Re: >Clipper trapdoor?
by Peter Wayner 12 Aug '93

12 Aug '93

Dave Sobel has been wondering just how the Escrow Agency will check up on the requests for keys that it gets from the NSA. The procedures aren't decided yet, but from my understanding of the presentation given at the last CSSAB meeting in Washington, the Escrow agencies won't have a person/phone to escrow id number mapping that would allow them to check if a request for a key is valid. There are two reasons for this. 1) It would be pretty useless because people could sell their phones at garage sales or give them as Christmas gifts and screw up the list. 2) This is also a "feature". If two of the escrow agents (from different agencies) decided to go bad, then they wouldn't be able to look up their enemy Bob's escrow key by name. They would need some of the real-time hardware and access to the family key. Presumably, this would be handled by a third party. -Peter

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ANONYMOUS CONTACT SERVICE
by Duncan Frissell 12 Aug '93

12 Aug '93

To: cypherpunks(a)toad.com H>A few months ago, someone subscribed to H>the list through the Penet service, H>and it ended up revealing the Penet H>aliases of everyone who posted. Each H>post was delivered to that subscriber H>marked as being from the Penet alias H>corresponding to the poster. All it took H>was a parallel non-Penet subscription H>to break the anonymity provided by Penet. H> H>Has this now happened again? Funny you should mention this. Maybe someone else just subscribed via penet since my morning post to cypherpunks was bounced back to *me* from penet (as well as being posted normally). The bounce was caused because penet was reading the originating address as *my* address (not cypherpunks) and since I have been using a penet password and my message did not contain the password, it was not forwarded. I have noticed that some postings show up here from cypherpunks and some from the address of the original poster. I suppose different mailing situations cause different results. Maybe all penet users on the list should activate passwords on penet.fi. Penet may search back along the chain of addresses for any familiar address to check against it's list of password-enabled addresses. Duncan Frissell H> H>At the time, there was some discussion H>about using "an..." versus "na..." H>forms of the Penet aliases, one of which H>would avoid this revelation. Has H>that been taken care of? H> H>Hal Finney H>hfinney(a)shell.portal.com H> H> --- ~ WinQwk 2.0b#0 ~ Unregistered Evaluation Copy

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Re: >Clipper trapdoor?
by David Sobel 12 Aug '93

12 Aug '93

RE>>Clipper trapdoor? Marc - You wrote: >As for the example of snooping on Hussein and his officers, you know >exactly how much legal authorization the NSA needs to conduct that >wiretap. Exactly none. Hence, it needs no paperwork to get the key >to Hussein's phone. > >How the escrow agents make the NSA prove that the keyid in question >belongs to Hussen's phone is an exercise left to the legislature :-/ As you (and others) noted in response to my posting, there is either a trapdoor *or* a "national security exception" to the warrant/escrow arrangement. As your comment suggests, NSA has heretofore been able to act unilaterally in exercising its "legal authorization" to intercept communications overseas, but with the Clipper scheme must obtain assistance from a third (and fourth?) party -- the escrow agents. I think the question you raise is a critical one -- under what guidelines will the escrow agents determine the validity of an NSA request for the key without a FISA warrant? - David

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chaos harnessed for encryption
by klaus＠mail.lds.loral.com 12 Aug '93

12 Aug '93

There is an article in some paper magazine (Technology) about some research at MIT for creating a signal-processing designs that use chaos to encrypt information. Voice telephone would be an excellent use of this technology. Anyone have more info on it? -- Christopher Klaus klaus(a)mail.lds.loral.com cklaus(a)hotsun.nersc.gov

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No Subject
by nobody＠shell.portal.com 12 Aug '93

12 Aug '93

At 12:25 PM 8/9/93 -0700, Timothy C. May wrote: >despite the talk of >mandatory "trap doors" in encryption systems, encryption is >fundamentally easy to do and hard to detect. (For those who doubt >this, let me describe a simple system I posted to sci.crypt several >years ago. An ordinary digital audio tape (DAT) carries more than a >gigabyte of data. This means that thhe least significant bit (LSB) of >an audio DAT recordingng carries about 8megabytes of data! So Alice is >stopped by the Data Police. They ask if she's carrying illegal data. >She smiles inocently and say "No. I know you'll search me." They find >her Sony DATman and ask about her collection of tapes and live >recordings. Alice is carrying 80 MB of data---about 3 entire days >worth of Usenet feeds!---on each and every tape. The data are stored >in the LSBs, completely indistinguishable from microphone and >quantization noise...unless you know the key. Similar methods allow >data to be undetectably packed into LSBs of the PICT and GIF pictures >now flooding the Net, into sampled sounds, and even into messages like >this... Alice better not be carrying any software that could retrieve that data. The cynic in me suggests that this scenario is just an excuse for the data police to seize any equipment or data it feels like. Besides, Alice won't be stopped by the data police, Alice will have her door kicked in by the data police and they'll take everything electronic she has, including harmless music and video. And anything electronic they find in her residence, whether it belongs to her or not.

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