June 1993 - cypherpunks-legacy

Re: Karn's note...
by karn＠qualcomm.com 25 Jun '93

25 Jun '93

I tend to doubt that the spooks have voice recognition technology in regular widespread use, at least not the kind of ultra sophisticated stuff that AI types seem to dream about. It's possible that they use less sophisticated stuff as a "pre filter" (compress out silence, perhaps distinguish male from female voices, etc), but I'm sure that the bulk of the work is still very labor intensive. Tens of thousands of clerks, intercept operators and natural language translators have long been employed by the NSA and there don't seem to be mass layoffs of these sorts of people around Fort Meade. And sophisticated voice recognition really isn't necessary when you consider all of the information that cell phones and base stations emit that is almost trivially processed automatically by an intercept device: electronic serial numbers, Mobile Identification Numbers (telephone numbers), handoff messages, channel assignment messages, etc. It's no big deal at all to build boxes that automatically intercept all calls made to or from a specific phone, assuming you have an RF path to the target (e.g., from a car tailing a suspect). As a manufacturer of cellular telephones, we have such a box (commercially made by IFR) in our lab. We use it to test our phones in their FM/analog mode. The spooks (NSA and otherwise) simply cannot be uninterested in boxes like these -- and in preserving their capabilities. One point I keep making about Clipper: it makes this sort of automated identity tracking as easy on regular telephone lines as it already is on cellular, because the chip serial number in the Law Enforcement Block can be decrypted with just the (common) Family Key - you don't need the escrowed keys. And sometimes simple traffic analysis can be almost as deadly as getting the actual contents of a conversation. Phil

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Karn's note...
by Peter Wayner 25 Jun '93

25 Jun '93

On Over-the-air encryption... If anyone wants to read Tom Clancy's latest book, _Clear and Present Danger_ about a set of covert operations against drug kingpins in South America, they will note that he mentions a magic box that will scan the airwaves for voices on the cellular channels. This allows the protagonists to follow the conversations of the kingpins as they hop from limo to limo using a different phone with each conversation. Does TriggerFish do this? My theory is that the 260-bit repeated XOR code was proffered because it wouldn't interfere with algorithms that were doing simultaneous voice recoginition. It is, after all, just the equivalence of doing a discrete convolution across the signal. I believe that this should be easy to handle with a few clever signal processing algorithms designed for noise reduction. I don't know this with any stretch of confidence so I would like to be disabused of this idea if it's harder than all of that. --Peter

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Triggerfish
by Phil Karn 25 Jun '93

25 Jun '93

I just posted this to the CU (Computer Underground) digest in response to a most interesting series of items about the newsletter Full Disclosure's public mention of a Harris Corporation device marketed to law enforcement agencies for intercepting cellular telephone conversations named "Triggerfish". Harris responded with an amazing threat to sue the newsletter for a variety of offenses, including trademark infringement (for merely mentioning the product in a brief "new products" editorial). The CU digest can be read on the usenet newsgroup comp.society.cu-digest; the issue in question is Volume 5, Issue 46. Phil To: tk0jut2(a)mvs.cso.niu.edu Reply-To: karn(a)servo.qualcomm.com Subject: Re: Cu Digest, #5.46 In CU Digest 5.46: |> Harris Law Enforcement Products |> |> TRIGGERFISH has a number of cellular phone based applications: |> determining a suspects phone number, dialed number recorder, and |> wiretapping. According to Harris, ``for the first time, law |> enforcement is not at a disadvantage in tracking the high-tech |> criminal.'' Additionally, the unit ``collects and integrates all |> relevant data, including voice, directly from the ether.'' |> Reprinted from Full Disclosure, Box 903, Libertyville, Illinois 60048 I find the phrase "directly from the ether" *most* illuminating given a rather heated exchange I had with Mr. Jim Kallstrom of the FBI at the recent CPSR Cryptography Conference in Washington DC earlier this month. Kallstrom is the FBI's chief public advocate for their "Digital Telephony Initiative". Among other things, they want the ability to intercept suspects' cellular telephone calls at the MTSO (switch). Only with a valid warrant, naturally. At the meeting, I made the following comments. I had seen the standards-setting process for the new digital cellular telephone systems from the inside as they related to security and privacy. And I was wondering why the government (specifically NSA, through its export control reviews) was so strongly opposed to meaningful air link encryption, even if the encryption were to stop at the switch as it would have to in order to be compatible with existing telephones on the land side of a cellular call. Such encryption would secure the air link, the most easily intercepted portion of a cellular telephone call, while leaving the conversation in the clear at the MTSO where it could be tapped, if necessary. In a private conversation, one of the senior members of the committee who didn't want his name mentioned told me why. "It's very simple", he said. "Anybody can intercept the radio link. It's easy. But tapping a call at the switch requires the cooperation of the telephone company, and they generally require warrants. And law enforcement says that sometimes, warrants are, well, just too damn inconvenient." This really set Kallstrom off. He shouted me down, attacking my unwillingness to name my source. I challenged him, unsuccessfully, to back up *his* shrill claims for the absolute necessity of Digital Telephony with anything more than handwaving. After tempers cooled a bit, in a one-on-one conversation during a break, he insisted to me that the FBI was never interested in intercepting the air link portion of cellular calls - "too difficult, too labor-intensive", he said. He agreed that he'd like to see cellular air links encrypted. They only wanted the capability to tap in at the switch, and he couldn't care less if the air link were securely encrypted (though he still wanted the keys to be escrowed for some reason...hmmm...) Perhaps it was a desperate attempt to maintain this "we're not interested in the air link" fiction that triggered Harris's silly overreaction to the public mention of TRIGGERFISH. Phil

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Re: Weak steganography
by nobody＠rosebud.ee.uh.edu 25 Jun '93

25 Jun '93

-----BEGIN PGP SIGNED MESSAGE----- Several people have suggested that PGP or some similar public-key program could be used to exchange encrypted email, then a "fake" one-time pad file could be created to transform the PGP file into a safe plaintext. If your files were seized and the keys demanded, you could supply the fake OTP file as the key which would "decrypt" the PGP file to the safe text. Unfortunately, this doesn't presently work with PGP. PGP puts a header at the front of encrypted file which identifies it as a PGP file. This includes information about whether the file is RSA or IDEA encrypted, and if it is RSA encrypted it includes information about which key(s) it is encrypted with. If files are saved like this, there will be no question that they are actually PGP files, and not the output of a one-time pad. Any attempt to produce a OTP key file which leads to a safe plaintext will be a transparent fabrication. And, of course, PGP's ASCII encoding, which would usually be used for email, boldly displays the "-----BEGIN PGP MESSAGE-----" at the top. If the files were saved in this format it would be a further giveaway. People have called for PGP to have a "stealth" mode in which it would save files without these headers. This would require the user to know which files were truly PGP encrypted, what the encryption algorithm was, and of course the key. If this were implemented it would make PGP files much less recognizable and the "fake OTP key" approach would be workable. Another approach for now would be to super-encrypt the PGP file with some other system. A simple XOR with a repeated random bit pattern (produced by hashing a user pass phrase) which is longer than the PGP header would be adequate, since the non-header portion of a PGP file should be random. Or you could use one of the widely-available DES encryption utilities, since these don't produce any headers, as far as I know. But this would complicate the process of decrypting the file. PGP's IDEA-encrypted files, which you create with the "-c" switch to PGP, put only a five-byte header on: a type byte, and a four-byte file length. This information is redundant and it should be very easy for PGP to recon- struct it if it were removed. RSA encryption headers will be harder to remove, particularly because of the lack of a key ID to tell which secret key to decrypt with. We would just try the default key, I guess. But this would require a more extensive set of changes to PGP. Hal Finney hfinney(a)shell.portal.com -----BEGIN PGP SIGNATURE----- iQCVAgUBLCmngKgTA69YIUw3AQGDWgP/U/HwP5gwPXn3GZgH3SH3zjnrKd8dHPqn y2OVF7xqiaVPuV5VF/UBGzFcPgfb/DuamIEr/aQmAMX2BlVktQ/fGaluZ8wvIbs/ QlQcsp+BH9AAb0BcojQ6rmwtf8A5c/3VkuGUSvyRGEX1PecdwoW8Eh/FEIfeU/WE njvIwmn92aY= -----END PGP SIGNATURE-----

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Re: Government fear of strong crypto
by Peter Wayner 25 Jun '93

25 Jun '93

I seem to remember that Pres. Reagan authorized the NSA to help domestic law enforcement officials when "lives were at stake." But I don't have a citation. -Peter Wayner

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Re: Government fear of strong crypto
by Doug Porter 25 Jun '93

25 Jun '93

Jim McCoy says: > The NSA is not chartered for domestic surveillance work. This statement keeps showing up. If there is any support for it I'd like to hear it. We know it was not true as far back as twenty years ago, from July 1, 1969 to October 1973. For details on the MINARET Charter see page 150 of "The National Security Agency and Fourth Amendment Rights", and pages 323 and 324 of "The Puzzle Palace". NSA has a long history of ignoring whether they are chartered for an activity, of course. Doug

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Perspectives
by Dr. Cat 25 Jun '93

25 Jun '93

The letters John Gilmore received through FOIA are interesting. So are the reactions of the cypherpunks. I think it's valuable for society to have a group of people examine such information in an extremely skeptical manner, even bordering on paranoia. The notion that these documents are a ploy to fool people into thinking the government is aware of the problems with their proposal and has weighed them carefully is worthy of speculation. Such thoughts lead to potential avenues of investigation that may turn up useful information. But there seems to be an overabundance of such views... I think the cypherpunks can better serve society by considering ALL possibilities and investigating the more plausible ones. Including the possibilities that some of the bad guys aren't maximally devious, competent, or even bad guys. I see a lot of use of the word "they", as if the Department of Defense was part of the same group of people as NIST, NSA, the president, etc. etc. and they all are working together with the exact same set of goals and motivations. I think the situation in Washington is more complex than that. And DoD is one player I haven't heard anything previous about with regard to their stance on and involvement with Clipper. In addition to the notion that they totally support Clipper, it should be considered whether they might totally oppose it (unlikely), whether they've chosen not to be involved in the struggle over it and are simply trying to analyze its potential effects on them and disseminate the information internally to be better prepared, or whether perhaps there are differences of opinion between varying individuals in the DoD power structure. And of course, even if you label them bad guys, there's the possibility that someone wanted a summary of valid opposition arguments in order to be able to combat them more effectively, and naively failed to adequately protect them from being revealed to the opposition through the FOIA. I don't have any particular opinion as to what's going on here. I just feel I ought to say something any time I only see one point of view represented in a discussion of such a complicated issue. Particularly when such a small portion of the relevant information is, thus far, available. Dr. Cat

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Fermat Vindicated Maybe
by Duncan Frissell 24 Jun '93

24 Jun '93

>From today's NYT: Dr. Wiles [Andrew Wiles of Princeton University] presented his results this week at a small conference in Cambridge, England, his birthplace, on "Padic Galois Representations, Iwasawa Theory and the Tamagawa Numbers of Motives." He gave a lecture a day on Monday, Tuesday, and Wednesday with the title "Molecular Forms, Elliptic Curves and Galois Representations." There was no hint in the title that Fermat's last theorem would be discussed, Dr. Ribet said. "As Wiles began his lectures, there was more and more speculation about what it was going to be," Dr. Ribet said. The audience of specialists in these arcane fields swelled from about 40 on the first day to about 60 today [23 June]. Finally, at the end of his third lecture, Dr. Wiles concluded that he had proved a general case of the Tatiyama conjecture. Then, seemingly as an afterthought, he noted that that meant that Fermat's last theorem was true. Q.E.D. Duncan Frissell The bulk of whose experience with Fermat consists of a close reading of "Mathmateca Fantasia" and other maths science fiction as an adolescent. Loved the 5 color map theorem as well.

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Re: Timothy C. May:superhacker
by hkhenson＠cup.portal.com 24 Jun '93

24 Jun '93

A lot of people are afraid to ask if the goverment keeps files on them-- because they would be disapointed to find out that they have never done anything to warrant the government opening a file on them. I have never asked the feds, but I had an interesting experience with what a reporter had been given suposedly from a local police file. During a time I was starting a business (and had no time for such nonsense even if I had been so inclined) they had me pegged as the leader of a local group of eco terriorist who were buring down houses to contain "urban sprawl." I felt the file (I did not get a copy) was real, because I could remember a few things from several years previous I had done while under survailance, but, gad, I didn't even *know* any of the bozos who were eventually caught. At least in that case, the quality of the data in my file was complete nonsense. Keith

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Testing remailers
by nobody＠shell.portal.com 24 Jun '93

24 Jun '93

This is a remailer test. This message has just passed through 16 remailers. Sorry for the waste of bandwidth. Have a nice day.

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