December 2003 - cypherpunks-legacy

NSA Insecure Remailers?
by analyst＠netcom.com 17 Dec '03

17 Dec '03

I was thinking about remailer traffic analysis this evening and realized that everybody who has come into contact (i.e. received or sent email to a remailer) with a remailer is probably on an NSA list. Given the low volume of information on the Internet backbone, only 45 Mbits/sec, it is not hard to imagine that they at least perform routine traffic analysis looking for things like packets going to and from remailers (unless I'm missing something--please correct me). Encryption doesn't help here because the header info isn't encrypted. Given that most remailers are not randomly changing the sizes and delay times of incoming and outgoing traffic, this probably also allows someone like the NSA to correlate incoming and outgoing traffic and follow messages end-to-end (until they leave the NSA surveyed portions of the network, anyway). Given the magnitude of the traffic analysis problem (I estimate about 24 gigabytes/day of addressing info saved: 45 Mbits/sec,86400 sec, 5% of data is addressing), probably only the NSA and some defense agency we haven't yet heard of are actually performing this analysis right now. But given the declining price of storgae media, even saving everything on magnetic media and paying $1000/gig, it only costs about US$8.7 million to keep a year's worth of traffic headers around (media cost). So what? Well if Blacknet exists, it either means they are using something trickier than the anonymous remailers that I know about or they are going to be quickly washed up--at least if they do anything to run afoul of the big guys (or maybe they're just a trot line for unsuspecting cypherpunks?). I also don't know how much information you can get out of just header analysis--for example, would this allow tracing anonymous posters into Usenet newsgroups? I suppose there are still things that you can do in the presence of such surveillance to avoid detection: multiple remailer chains off of the main backbones for example--which I may not currently know about. I hope I have made some obvious errors that list readers can correct, but my assessment of the security provided by using anonymous remailers just dropped an order of magnitude. It sounds like I need to learn about mixes and DC-nets about now, which I presume are part of the solution to this dilemma? I have the dining cryptographers paper, could someone point me towards more info? Thanks. --------------------------------------------------------------------------- --- Benjamin McLemore analyst(a)netcom.com

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Eric Hughes & the Cypherpunks Movement
by L. Detweiler 17 Dec '03

17 Dec '03

There was an interesting article in RISKS 15.28x on pseudoanonymity by E.Hughes. Comments on pseudospoofing and pseudoanonymity by leading Cypherpunks are *extremely* rare, and we have to prize every one! I have asked many times and in many variations for more of these precious gold nuggets, but results have been unrewarding over the past few weeks. There has been a lot of commotion on the list lately on the subject of pseudospoofing, and maybe if the Eminent Leaders came out with a public statement on their personal knowledge, opinion, and involvement in pseudospoofing many people would be less upset, and the noise would die down! Just a hypothetical speculation, of course! They must have excellent reasons for withholding one for this long, even in the face of tremendous public and private pressure! (If anyone knows what those reasons are, could you tell me?) Anyway, on to this letter. The most interesting aspect of it is its brevity. Many interesting implications were raised in RISKS 15.25 and 15.27 about the cryptoanarchist movement in black marketeering, tax evasion, and sabotage of governments, and whether Cypherpunks == Cryptoanarchists. There was also insinuations of a secret mailing list, manipulation of others, widespread deception of the media and a massive hoax and conspiracy, a rampant pseudospoofing effort by the leadership behind the scenes, even involving customized software, a Cult Religion of Pseudoanonymity, etc. (You all know the black, sordid story!) Unfortunately, much to my disappointment, the Eminent Leader did not comment on any of these issues. But nevertheless I would like to analyze what little was available. The major point to make about this person is that everything he writes is extremely carefully crafted to have a precise, intended effect. I imagine that he spent a very large amount of time on this short posting, making sure that it did not contain any incriminating statements. It is a masterpiece of a deceptive and evasive message that supposedly appears to `set the record straight' while actually being completely, utterly empty of any true reassurances or denials. >L. Detweiler's recent article on the RISKS of confusing an online >identity with a potentially knowable physical one are quite >interesting, if hypothetical. Interesting the phrasing of `if hypothetical'. There is no indication of any personal knowledge of the veracity of any of the hypothetical situations. But! At the same time there is cleverly no statement in the form, `I am not aware of any' or `I can assure you that they do not exist' despite that this person would be in a position to issue a statement of this sort, and that exactly such a statement is what is called for. >I would be interested in hearing of situations where this practice >has actually occurred. If any RISKS members know of any such >incidents from first-hand experience, please share them with the >readership. This is another extremely clever method of evading any personal association, accountability, or responsibility for the issues raised. This eminent leader is personally aware of a massive pseudospoofing framework, namely his own, yet makes it appear he has no knowledge of any by requesting information from others. Quite ingenious! This was very similar to N.Szabo asking others for `pseudospoofing tools' and `posting sites'. The entire problem with pseudospoofing, of course, is that in the well-conceived cases only the practitioner has the kind of `first hand experience' the eminent leader requests. >Unfortunately, I think he really believes that the cypherpunks mailing >list has been dominated by a small cabal who have been using multiple >identities who talk with each other on the list in order to enforce >concensus and to suppress disagreeing positions, namely his. This is a clever method of (1) attempting to discredit L.Detweiler as someone who believes that all people who disagree with him are co-conspirators, and (2) not specifically mentioning those positions, and (3) reformulating the many issues of RISKS 15.25 which are extremely wide-encompassing, into a simple question of `a small cabal on the list' who `disagrees with L.Detweiler'. These are all quite ingenious ways of `begging the question' so to speak. >It just ain't so. Despite the exchange of probably over a hundred messages in my cypherpunk lifetime with this eminent leader, and reading dozens of his public postings, I've never seen this eminent leader use a colloquialism like `ain't' and its appearance, especially in this context, is quite curious! Notice how he doesn't actually state *what* isn't so, like `there is no cabal' or `I have no personal knowledge of anyone posting under fake identities.' Overall this is another meaningless statement that does not actually imply anything whatsoever. >Therefore, to set the record straight I feel I ought to make the >following public statement: Note that this statement below does not `set the record straight' on many of the issues raised, in particular the eminent leader's personal knowledge of pseudospoofing. >I, Eric Hughes, have never posted or communicated in any name other >than my own. Frankly, I think this is a baldfaced lie. The eminent leader would be implying, if it were to be taken literally and exactly, that he has never used the anon.penet.fi server or any account other than one with his name. What precisely does he *mean* by this statement? How are we to be sure? We need a direct answer to the question, ``What accounts have you posted from, and how were they identified?'' I have many examples of a Medusa claiming `I, Medusa, have never posted or mailed under any other name than Medusa.' This is because under the fanatic religion of pseudospoofing, the cultists actually maintain that the different `personalities' under the assorted `nyms' of a person actually constitute *different* *people*! This, of course, is a blasphemous abomination of the English language, warped to their own ends of deceit, very much like the use of the term `true anonymity' by N.Szabo or `pseudonym' by J.Gilmore. >I can personally testify that I am not the same as any >of the other people listed at the end of L. Detweiler's post, and I >can testify from personal experience that Arthur Chandler, Hal Finney, >Tim C. May, and Nick Szabo are all different people. This is an interesting statement. Again, I think it is a baldfaced lie. Notice that the eminent leader writes previously that `I have never communicated under any name other than Eric Hughes.' All of these statements would be superflous under that statement, if it were true. But he finds it necessary to be more specific, for some curious reason. The question in cyberspace is not about `people', but computer accounts, as in, `Have you ever posted a message from any of these accounts'? For example, if E.Hughes sent me mail that ``I have never been the originator of a message from the G.Broiles site goldenbear.com'' I would take that as authoritative. But he has never answered any of my questions in any specific form. Even questions like `How many pseudoanonymous identities are you using' he (and T.C.May) refuses to answer. >I also decline to answer, point by point, the numerous defamatory >innuendos made by L. Detweiler against the members of the cypherpunks >mailing list. Hee, hee, `defamatory innuendos' is a clever term. He does not actually point to any specific `defamatory innuendo' as defamatory! They are only defamatory if you can state they are false! Also, many of the comments are not directed at `members of the cypherpunks list' but at the *leadership*. But we have another ingenious diversion. The eminent leader implies that a `point by point' statement would be tedious and unjustified. I assure you, I would prize it beyond anything in my ~3,500 message collection of cypherpunk archives. > Might I also observe that none of the statements are >specific enough to actually count as accusation, but merely as general >slander? Another rather silly statement. Eminent leader E. Hughes, after many weeks of my trouble, has never answered *either* my `defamatory innuendoes' or my `specific accusations'. Imagine the sheer artillery that would be for your hordes of cultists who continue to assault me, Mr. Hughes! ``Mr. Hughes answered all your charges. Go to hell.'' * * * Why do I persist at this? Because the Cypherpunks wish to pretend that they are a respectable organization on the level of EFF or CPSR, with leaders on par with say, Barlow, Sobel, or Kapor or Godwin. The simple fact is that they are an obnoxious, arrogant, pathetic, repulsive bunch of cyber-guerrilas, pseudospoofers, and quasi-criminals who have no unity other than a Internet mailing list, which itself is used as a testbed for pseudospoofing perversions on unsuspecting and unwilling participants and cryptoanarchist disinformation and brainwashing. Oh, how I have given you the benefit of the doubt, and gone to great lengths to respect you! But your leaders are either undoubtedly corrupt or accomplices, with more interest in secret conspiracies, pseudoanonymity perversions, trust embezzlement, manipulation, and predation, privacy invasion, pornography, ego assuagement, elitist clique parties, and aquiring and dazzling their personality worshippers than anything substantial, such as Internet project development, that involves things upon which you urinate, like cooperation and openness. You cling to your elaborate fantasies with gripping white knuckles. Cypherpunks are blind to the ashes of their arson. `The Tyrant is not that bad!' `Hell is not such a bad place!' `Look how much we have accomplished'! You have nothing but gimmicks, trinkets and playthings, not a `foundation' but deadly quicksand traps. The only observation is that everything substantial accomplished by others you have done a great deal to simultaneously take credit for and maliciously sabotage, and everything you have accomplished is not substantial, and never will be, as long as you wallow in your gutter. But you are not content to wallow alone! You must drag the Current Internet and Future Cyberspace into your filth. I think that real leaders such as Zimmermann, Chaum, Card, and Sterling should have the sense to not only distance themselves but to condemn your parties of freakshow perversions. The cypherpunks list is a magnet for criminal apologists, moral relativists, libertarian extremists, demogogues, poseurs, and hypocrites. Frankly, I'm quite upset that respectable journals, like Wired, NYT, and RISKS have been subtly twisted and corrupted with the depraved Cypherpunk fantasies and lies. These knotty deceptions take an extraordinary amount of energy to untangle, and there is enough here to keep historians busy for decades. I'm grotesquely ashamed to have ever been associated with this sham, this mockery, this farce, that masquerades as a `group' or a `movement'. I have even lended credibility to tentacles by quoting them in my FAQs and in RISKS, oh how that makes me want to vomit. `Anonymity on the Internet' -- more like Disinformation, Brainwashing, and Lies by Tentacles. The cypherpunks list does not deserve to be advertised *anywhere* except as a dark pit to be avoided at all costs, the cypherpunks Movement is no more meaningful than graffiti spraypainted on a wall. It was only an infinitesimal whit better when it was just spread by word of mouth among the conspiring CA slime. Please, go back to your dark holes where you came from, and take your odious `movement' with you. Oh, what insidious despicable poison.

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a correction
by L. Detweiler 17 Dec '03

17 Dec '03

I wrote: > [The `Movement'] was only an infinitesimal whit better when it was just >spread by word of mouth among the conspiring CA slime. By `better' I meant -- `less evil'

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Re: Eric Hughes & the Cypherpunks Movement
by koontzd＠lrcs.loral.com 17 Dec '03

17 Dec '03

>I'm grotesquely ashamed to have ever been associated with this sham, >this mockery, this farce, that masquerades as a `group' or a >`movement'. I have even lended credibility to tentacles by quoting them >in my FAQs and in RISKS, oh how that makes me want to vomit. `Anonymity >on the Internet' -- more like Disinformation, Brainwashing, and Lies by >Tentacles. The cypherpunks list does not deserve to be advertised >*anywhere* except as a dark pit to be avoided at all costs, the >cypherpunks Movement is no more meaningful than graffiti spraypainted >on a wall. It was only an infinitesimal whit better when it was just >spread by word of mouth among the conspiring CA slime. Please, go back >to your dark holes where you came from, and take your odious `movement' >with you. Oh, what insidious despicable poison. (In your best N.E. accent) "ahll righht, who faarted?!"

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Chaos Communications Congress 1993 (fwd)
by Anonymous 17 Dec '03

17 Dec '03

From: bkr(a)drdhh.hanse.de (Bjoern Kriews) Newsgroups: comp.org.eff.talk,comp.security.misc Subject: Chaos Communication Congress 1993 Date: 26 Nov 1993 08:10:08 +0100 Organization: Digital Island Message-ID: <bkr.754297770@drdhh> NNTP-Posting-Host: drdhh.hanse.de [Sorry for crossposting this to so many groups - last year I received complaints that people didn't find the announcement] "Ten years after Orwell" 10th Chaos Communication Congress, Hamburg, Germany The Chaos Computer Club invites the global community to participate in the Chaos Communication Congress in Hamburg and celebrates the tenth anniversary of this convention. This hackers' meeting, taking place annually at the end of December, has become a traditional event which is characterized by a colorful mixture of absolute chaos, serious discussion and detailed presentation. Computer enthusiasts, scientists from well-known institutions, lawyers, politicians, artists and, of course, hackers as well as data-travellers and Internauts from many countries are going to meet at the 'Eidelstedter Buergerhaus' on December 27th-29th for an interdisciplinary exchange of data and other experience. Not only concentrating on technical topics, political and social issues will be focal points of discussion this year. After ten years of creative future concepts the time has come to look for achieved goals and new visions for the future. This year's list of topics: The so-called "great peep attack" (a proposed law reform allowing state authorities to listen in, even in private rooms, in order to fight organized crime) affects every german citizen and is considered one of the most important issues of the year. - What is technically possible? - What is planned and/or wanted politically? - How do the right of privacy and ban of encryption software fit together? Well-informed speakers talk about state-of-the-art technology and legal limits. Public discussion forums invite you to form your own opinion. Money always serves for interesting talk: - How can we improve Electronic Cash? - How to print your own money - How to wash it if it's dirty - How to open electronic cash machines without damaging them It's up to you to add to this list... Hardly noticed by the public, the female part of the hacker scene is growing. Female hackers' activities have become a regular part of the congress, the workshop on feminine computer handling is one of the key events. For the first time, there will be a Women Only room with lots of equipment to try out, opportunity to ask and learn as well as to discuss and create. Other highlights: Discussions and workshops on - citizen networks and electronic democracy - ISDN, MODACOM (german mobile radio data network) and Beepers - Bluebox versus Telekom - Electronic Warfare - Chip- and other cards - inventory differences - underground radio stations - Computer recycling - lockpicking - MIME and *ostscript viruses - copyright law and the GNU generation. Furthermore: the Hackcenter, the Chaos Cafe, the Chaos Archive, the movie theatre (among others: educational propaganda films by the former East German Ministry of State Security), a Zerberus BBS, the Internet-FreePort and lots of other things we forgot to mention. Feel free to contribute more interesting topics, workshops or presentations. Anyway, the hottest news for computer enthusiasts and hackers will be those you won't find in the press. What: 10th Chaos Communication Congress When: December 27th - 29th 1993 Cost: DM 42,- Three-day-ticket Where: Eidelstedter Buergerhaus Alte Elbgaustr. 12 D-22523 Hamburg +49-40-5710523 Contact: Chaos Computer Club Schwenckestr. 85 D-20255 Hamburg Germany Phone: +49-40-4903757 Fax: +49-40-4917689 E-Mail: ccc93(a)t42.ccc.de Press contact: Phone: +49-161-2447146 (european afternoon, please) For reservations in an inexpensive hotel (approx. DM 30,-/night), mail to: sleep(a)drdhh.hanse.de #!/bin/thanks to P. Kane for the word 'InterNaut'. -- bkr(a)drdhh.hanse.de - Bjoern Kriews - Stormsweg 6 - D-22085 Hamburg [76] - FRG By definition, a properly functioning kernel doesn't allow user programs to make it crash unless they say "please". (Richard Stallman)

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EFF Op-Ed from the NY Times
by Anonymous 17 Dec '03

17 Dec '03

From: mech(a)eff.org (Stanton McCandlish) Newsgroups: comp.org.eff.talk Subject: EFF Op-Ed from the NY Times Date: 30 Nov 1993 11:38:52 -0500 Organization: EFF mail-news gateway Message-ID: <199311301632.LAA28210(a)eff.org> NNTP-Posting-Host: eff.org Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit >From the New York Times Op-Ed Page, Wednesday, November 24, 1993 A Superhighway Through the Wasteland? By Mitchell Kapor and Jerry Berman Mitchell Kapor is chairman of the Electronic Frontier Foundation, a nonprofit group that promotes civil liberties in digital media. He was a founder of the Lotus Development Corporation, from which he resigned in 1986. Jerry Berman is executive director of the foundation. (Washington) Telecommunications and cable TV executives, seeking to allay concerns over their proposed megamergers, insist that the coming electronic superhighway will be an educational and informational tool as well as a cornucopia of interactive entertainment. Allow the marriage between entertainment and communications giants, we are told, and they will connect students with learning resources, provide a forum for political discourse, increase economic competitiveness and speed us into the multimedia information age. Both broadcast and cable TV were introduced with similar fanfare. The results have been disappointing. Because of regulatory failure and the limits of the technology, they failed to be saviors of education or political life. We love the tube but recognize that it is largely a cultural wasteland. For the Government to break this cycle of promise and disappointment, communications mergers should be approved or barred based on detailed, enforceable commitments that the electronic superhighway will meet public goals. The amount of electronic material the superhighway can carry is dizzying compared to the relatively narrow range of broadcast TV and the limited number of cable channels. Properly constructed and regulated, it could be open to all who wish to speak, publish and communicate. None of the interactive services will be possible, however, if we have an eight-lane data superhighway rushing into every home and only a narrow footpath coming back out. Instead of settling for a multimedia version of the same entertainment that is increasingly dissatisfying on today's TV, we need a superhighway that encourages the production and distribution of a broader, more diverse range of programming. The superhighway should be required to provide so-called open platform services. In today's channel-based cable TV system, program producers must negotiate for channel space with cable companies around the country. In an open platform network, we would avoid that bottleneck. Every person would have access to the entire superhighway, so programmers could distribute information directly to consumers. Consumers would become producers: individuals and small organizations could create and distribute programs to anyone on the highway who wants them. Open platform services will spur diversity in the electronic media, just as low production and distribution costs make possible a wide variety of newspapers and magazines. To prevent abuses by media giants that because of recent Federal court decisions will control the pipeline into the home and much of the content delivered over it, we need new laws. Like today's phone companies, the companies controlling the superhighway must be required to carry other programmers' content, just as phone companies must provide service to anyone who is willing to pay for it. We must guarantee that anyone who, say, wants to start an alternative news network or a forum for political discussion is given an outlet to do so. Americans will come to depend on the superhighway even more than they need the telephone. The guarantee of universal telephone service must be expanded to include universal access to the superhighway. Although market forces will help keep the new technology affordable, we need laws to protect consumers when competition fails. And because several companies will operate the highway, each must be required to interconnect with the others. Likewise, the new computers that will give us access to the superhighway should be built according to commonly accepted standards. Also, even an open, competitive market will leave out organizations with limited resources such as schools and libraries. To compensate for market oversights, we must insure that money -- whether through Federal support or a tax on the companies that will control the superhighway -- is made available to these institutions. Finally, people won't use the new technology unless they feel that their privacy is protected. Technical means, such as recently developed encryption techniques, must be made available to all users. And clear legal guidelines for individual control over access to and reuse of personal information must be established. Companies that sell entertainment services will have a record of what their customers' interests are; these records must remain confidential. Bell Atlantic, T.C.I., Time-Warner, U.S. West and other companies involved in proposed mergers have promised to allow the public full access to the superhighway. But they are asking policy makers to trust that, profits aside, they will use their new positions for the public good. Rather than opposing mergers or blindly trusting competition to shape the data highways, Congress should make the mergers hinge on detailed commitments to provide affordable services to all Americans. Some legislators, led by Representative Ed Markey, Democrat of Massachusetts, are working to enact similar requirements; these efforts deserve support. The best approach would be to amend these requirements to the Communications Act of 1934. Still the central law on open access, an updated Communications Act would codify the terms of a new social contract between the the telecommunications industry and the American people. Copyright 1993 The New York Times Company

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Unsubscribe
by Louis Cypher 17 Dec '03

17 Dec '03

Please unsubscribe me. It was ok when I owned my own system, but now that I sold it, I cannot keep up with all the traffic. It was fun.

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WiReD has a gopher (and its name was...)
by Anonymous 17 Dec '03

17 Dec '03

Newsgroups: comp.org.eff.talk,alt.wired From: kadie(a)cs.uiuc.edu (Carl M Kadie) Subject: Wired Magazine's gopher Message-ID: <CHBE7B.Jt(a)cs.uiuc.edu> Organization: University of Illinois, Dept. of Comp. Sci., Urbana, IL Date: Tue, 30 Nov 1993 17:06:46 GMT Wired Magazine has a gopher. It includes many articles. Try gopher gopher.wired.edu I've also added it to the CAF whatsnew server. Try gopher gopher.eff.org 5070 - Carl ANNOTATED REFERENCES (All these documents are available on-line. Access information follows.) ================= admin/access ================= Information on how to access one computer medium via another: access anonymous ftp via email, access gopher via email, access gopher via telnet, read netnews via gopher, read netnews via telnet, write netnews via email, ftp via gopher. ================= admin/whatsnewd ================= * Code for and description of "whatsnewd" (v. 0.42) (Connect your Gopher to "gopher.eff.org", port "5070" to play with it.) It is a gopher-protocol server. What it does: When a user gives a date (e.g. "1 day ago") or enters a dated bookmark (generated by a previous query), he or she gets a gopher menu of the gopher items that are new or changed since that date. ================= ================= If you have gopher, you can browse the CAF archive with the command gopher gopher.eff.org These document(s) are also available by anonymous ftp (the preferred method) and by email. To get the file(s) via ftp, do an anonymous ftp to ftp.eff.org (192.77.172.4), and get file(s): pub/academic/admin/access pub/academic/admin/whatsnewd To get the file(s) by email, send email to archive-server(a)eff.org. Include the line(s) (be sure to include the space before the file name): send acad-freedom/admin access send acad-freedom/admin whatsnewd -- Carl Kadie -- I do not represent any organization; this is just me. = kadie(a)cs.uiuc.edu =

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Statistics of Low-Order Bits in Images
by tcmay＠netcom.com 17 Dec '03

17 Dec '03

Several folks have recently mentioned the need to carefully look at the statistics/distributions of bit values in the low-order bits (least-significant bits, LSBs) of real-world images intended for steganographic use. I concur. This problem interests me. Material from Li and Vitanyi's "An Introduction to Kolmogorov Complexity and Its Applications," 1993, bears directly on the issues of "picture distance" and how much one can change an image before it's recognizably "different" or before filter programs can detect the presence (or absence) of characteristic structure in images. In this little article I'll be making some general points and reasoning informally about image statistics, picture distances, and the like. There's no doubt a more rigorous way to reason about these statistical properties, using sigmas and summations and Central Limit Theorems and the like, but I'm not that much of a real mathematician to be bothered with that. C'est la vie. Several points: 1. Probably not a pressing concern, yet. I expect few sites have LSB-analyzers, just as few folks are using LSB stegonagraphy. 2. Romana Machado's "Stego" program for the Mac is interesting, and may be useful, but it makes almost no effort to hide the _existence_ of the message bits, e.g., anyone with a copy of Stego can apply it to an image and recover the plaintext or ciphertext. (I mean in contrast to some of the schemes which require a copy of the original image, a kind of one-time pad approach, in which one XORs or subtracts the original image to see the "differences" in the LSBs--a cryptanalyst without the "reference" image is unable to extract any bits for further analysis.) (I suggest we keep these two models in mind. Proposal for jargon: "Type 1 Stego": No reference model needed: message bits are just the specified bits, e.g., LSB, or larger low-order bits. "Type 2 Stego": a reference model--an image or DAT or whatever--is needed to XOR with message to recover the plaintext or ciphertext (if more encryption was used originally).) 3. With fairly noisy 8-bit images, such as might be gotten by frame-grabbing a video image under poor lighting or focus conditions, my experiences at Intel (I ran an image processing lab, for electron microscope analyis of microprocessors) tells me that the lowest _several_ bits of each pixel are "noisy." Very noisy. The bottom bit is "almost purely noise" (also a dangerous term!). But I agree that more recent images need to be looked at and the statistics analyzed. Still, I suspect the bottom bit, the LSB, will be found to have Gaussian noise characteristics. Note also that images are often run through filters, as in PhotoShop, which can give Gaussian characteristics where before there were none. 4. Can "image analyzers" in the hands of border security/law enforcement be used to proseute holders of images that have such white noise characteristics in the LSBs? I doubt it. I interject this point here because an important long-term issue for stego is whether the "Crypto Authority" (resonance with Gibson's "Turing Authority") can make such images ipso facto illegal. I suspect this is hopeless, both because many images have these characteristics and because many people will massage their images to be this way, regardless of original camera-CCD characteristics. 5. All of these arguments apply to the LSBs in DATs. Ambient room noise, noise in microphones, thermal noise in the electronics, etc., all contributes to there being almost no "signal" in the LSB of a 16-bit CD or DAT sample of music. (There are anecdotal reports of people being able to hear effects here, and different noise-shaping filters may have audible effects at least some of the time. So, I do agree that these statistics ought to be looked at, eventually. Some of my audio magazines have articles on this, which I'll try to look at soon.) 6. Here's a strategy which may work OK even if the statistical patterns of the LSBs are not "completely random" (a dangerous term, of course). - take a plaintext or ciphertext and compress it with a good compressor (L-Z may not be enough to wring out all the structure and raise the entropy to the full 8 bits per character, for ASCII). A good encryption of the text should of course produce high entropy. - XOR the compressed (high entropy) text with the LSBs of the image. - the resulting LSBs should have _similar statistics_ as compared with the original image. "Noise" has been added, but no knew structure has been added. Consider a couple of examples to see this: Original image (in bits) : 1 0 1 0 1 1 0 1 1 0 1 0 1 0 1 1 1 1 0 1 Random 1s and Os: 1 1 0 0 1 0 1 0 1 0 0 0 1 1 1 0 1 0 1 0 Resultant Image (XOR): 0 1 1 0 0 1 1 1 0 0 1 0 0 1 0 1 0 1 1 1 (Another example: If one toggles all the bits in a binary image, the "Hamming distance" between the images is maximal, and yet the "picture distance" is very small, i.e., the images look nearly the same. The picture distance being small means the structure is the same, even though the Hamming distance is, by definition, the greatest it can be. This provides a powerful clue that there is a "lot of room" to manipulate images so as to pack bits into this "Hamming space" while still keeping the resulting pictures in a "tiny picture space volume.") Well, this is of coure not a proof, but gives a feel for why XORing with a high entropy image will not _add_ structure. However, it can certainly _remove_ structure! Which takes us back to the original issue of the statistics (structure) of the LSBs of images. If in fact there were "clumps" of 1s and 0s, "ridges" and "valleys" caused by camera/CCD characteristics, then XORing the LSB image with a "random" image will demolish this structure. This is nothing more than the role of the one-time pad....to remove structure but allow its immediate reconstruction on the other end. At least in this case one does not have to worry about the ciphertext _adding_ unwanted structure, only that it may _remove_ structure already present in the image (and perhaps "typical" of images not carrying stego bits). 7. A better approach may be to take two very similar images, perhaps successive frame grabs with the same camera/digitizer, and use the statistics of the LSBs directly as part of the "one-time pad" above (Type 2 Stego). This could be used to give the LSBs the same "structure" (ridges and valleys of pixel values, for example) as a "real image" but without leaking message bits. (More work needed here.) (I apologize for any vagueness here. Partly it is that I haven't worked this out completely. Partly it is the lack of a blackboard to draw pictures on--verbal descriptions get confusing after a while. And partly it is that this message is already too long and I want to wrap it up.) 8. None of this subtlety really matters too much, I suspect. An image or DAT contains _so much room_ for stego bits that the problem of finding a tiny fraction of message bits in megabytes or hundreds of megabytes (DATs) of noisy source material seems well beyond current crunch capabilties. Perhaps images being sent to some sensitive location could be given a quick analysis to see if the LSBs are "too regular," but even this I doubt. And at least the XOR method described above won't introduce new structure....at worst the images or DATs would appear to be "too random." Perhaps we need to paraphrase Eric's line: "Use a random image, go to jail." --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: PGP and MailSafe available. Note: I put time and money into writing this posting. I hope you enjoy it.

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Unsubscribe
by Paul Gilberti 17 Dec '03

17 Dec '03

Please unsubscribe me. I really thought that this list was for serious discussion of crypto technology/news. Instead, I'm just tired of weeding through my mail of immature postings of posters who are afraid to post under their own names (DL), and all the traffic regarding the censorship of the same.

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democracy and L. Detweiler
by baumbach＠atmel.com 17 Dec '03

17 Dec '03

L. Detweiler is a champion of democracy. He has argued strongly for it here on this forum. I am not a supporter of democracy. A crowd of people has no greater rights than one person. L. Detweiler disagrees with this. I shall confront this disagreement with an example that strikes to its core. I propose a vote. This vote will have no time limit. If at any point you wish to change your vote you are free do so. This vote is non-binding on those who do not support democracy. This vote will be conducted publicly on this list. ======================================================================= VOTE: Proposition desist L. Detweiler will cease posting to the cypherpunks mailing list. He will no longer concern himself with the activities of those on the cypherpunks mailing list here or on any other forum. [I support]/[I Do not support] ======================================================================= L. Detweiler will be the only judge of the results of this vote. If he believes a majority of unique individuals carry this proposal one way or another, then by his honor and support for democracy he is bound by it. If he recants his support for democracy, then he is not bound by it. ------------------ I shall cast my vote here: I support Proposition desist. Peter Baumbach baumbach(a)atmel.com

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Re: The Cure
by hawkwind＠dink.foretune.co.jp 17 Dec '03

17 Dec '03

>It craves fame. It resents what it perceives to be the fame of the >better-known members of this list to be. It is jealous of that fame, >and wants some for itself. It is sick and ugly, small and unintelligent, >resentful of its underdeveloped brain and the fact that everyone he looks >up to instantly recognizes his stupidity. And now it has found a way to get >those very people to acknowledge it, discuss it, feel threatened by it. >It is used to rejection, so the endless repeats of it mean nothing. And >then even less in the face of the warm glow at the center of the >Cypherpunks collective attention. > >This is the first and the last word I'll ever write about about it. >If we all did that, it would go away. > >Coerr > REALLY excellently stated! Great analysis of the nature of the problem. Thank you, do you mind if I quote this to others? Alas, though, I can not from long and bitter experience agree with you about the solution. In the real world physical verbal/facial expressions of disapproval and disdain might rapidly rid the group of the problem person, but in cyberspace, such traditional cultural prods are non-existent. The aberrant user KNOWS he faces no meaningful penalties or censure and thus has no inducement not to continue his chaotic ways. I do feel that in addition to the observations you made above, that such people often take sheer perverse delight in the mere poisoning of the creativity of the group being creatively atrophic themselves.

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Who is this Detweiler guy anyway?
by an48848＠anon.penet.fi 17 Dec '03

17 Dec '03

As a fairly recent addition to this list, I'm unfamilliar with the history of cypherpunks. Can anyone enlighten me? Thanks. ------------------------------------------------------------------------- To find out more about the anon service, send mail to help(a)anon.penet.fi. Due to the double-blind, any mail replies to this message will be anonymized, and an anonymous id will be allocated automatically. You have been warned. Please report any problems, inappropriate use etc. to admin(a)anon.penet.fi.

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Re: Knights who say NII (was Crypto(A), govt & NII)
by fnerd＠smds.com 17 Dec '03

17 Dec '03

> Steve Witham writes: > > > Giving the government savvy advice, telling them they should do whatever > > will promote, say, competition or open forums...what effects will these > > have? They may provide justifications, expertise and targeting info > > for interventions, for instance. New ways to get involved... Mike Godwin replies: > The government is already tempted to get involved, all the time. We can't > make the government go away by resolving that it would be nice if they > weren't around. Best to work from where we are, not where we'd like to be. Sure, I agree. It's just, will the process-that-be have a tendency to be encouraged to intervention in general, by positive-sounding things in what you say. > > I can't think of one positive thing (as opposed to the negative thing, > > disengagement) government can contribute to the goals of EFF. On being true police, see below. > Government is not the only potential source of harm--private industry can > be plenty harmful. Private business can be nasty, slow and unhelpful, but short of physical sabotage and threats, they can't do nearly the kind of harm and prevention of alternatives that government does. > > ...the most centralized organization in the world as the > > decentralist's tool or ally doesn't seem workable to me. The > > means clashes against the ends. > > I don't see how. One actually can use a weapon to keep the peace, for > example. Yes, you're right. I wasn't thinking about that because I assumed there's a minimum of physical crime in the communications industry. But now that I think about it, there's one thing State governments could limit: local governments' interference (franchises) in communications. But other than real basic policing like that, the means clash with the ends. Government is okay at nabbing true bad guys, not at trying to steer people in good directions. > > Telling a bull that he should make whatever > > positive contributions he can to the china shop...is worse than just > > not mentioning that there are none. > > I think you're reasoning from your conclusions here, not toward them. Well, sure, I'm talking from my view of how things are. Mostly I'm just saying that the *need* for positive government involvement is dubious while the *danger* is obvious in the current state of things, and if you aren't always saying that, then your well-informed comments and laudible goal statements can be misconstrued more easily, because in certain circles, radical deregulation is not assumed. That's my not-so-humble-but-trying (IMNSHBTO?) point in a nutshell. Your participation without this particular sternness, may, as one side-effect, encourage and assist where we all won't be happy it did--and maybe it'll fail to push through the single most helpful idea. I know, it's not your particular hobbyhorse. It's just what I'm afraid will happen. > What's more, government ain't the only bull in this shop. Although the FCC is smaller than AT&T, there's nothing in private industry with the momentum, power and difficulty of correcting that our layers of government have. Business without the power of government behind it (which status-quo businesses do have right now) faces much more immediate corrective pressure than government. Even combinations of big nasty companies are less of a problem. Throw me in that briar patch, puh-*leeze*, it's better than this one. -fnerd(a)smds.com quote me -----BEGIN PGP SIGNATURE----- Version: 2.3a aKxB8nktcBAeQHabQP/d7yhWgpGZBIoIqII8cY9nG55HYHgvtoxiQCVAgUBLMs3K ui6XaCZmKH68fOWYYySKAzPkXyfYKnOlzsIjp2toust1Q5A3/n54PBKrUDN9tHVz 3Ch466q9EKUuDulTU6OLsilzmRvQJn0EJhzd4pht6hanC0R3seYNhUYhoJViCcCG sRjLQs4iVVM= =9wqs -----END PGP SIGNATURE-----

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What recipient-end mail filters are available?
by Anthony Garcia 17 Dec '03

17 Dec '03

I'm aware of two mail-filtering systems that operate at the recipient's end, procmail and Elm filter. Are there others? -Anthony Garcia agarcia(a)neosoft.com

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Entropy, Randomness, etc.
by jerry＠terminus.dell.com 17 Dec '03

17 Dec '03

With all this talk about entropy, randomness, and gaussian distributions, I'm hoping we can clear up some of the confusion that I am having. My understanding of a random number is a number is generated from two or more unrelated events. In order for this number to be most useful cryptographically, it needs a even distribution. This distribution is such that any one number in the range of possible values is equally probable as any other number. Does this make this distribution a gaussian distribution? Maybe I just don't understand the theory behind the random numbers well enough, but with all of these terms floating around it is hard to keep track. The reason I want to get some of these things clarified, is because I am becoming more interested in some of the analysis people have been talking about being possible. Also how are these statistical measurements done? Is it as simple as a histogram? (useful for simple alphabet transliterations). Are we talking frequency analysis with FFTs and more advanced things? How do we measure the entropy of a random number, or a series of random numbers? Have people on the list done this, or is this still in the range of people that do math and number theory for a living? Give a particular set of data used to generate a random key, such as, a unix box's /dev/mem, how can one measure the number of bits of entropy? These topics are probably covered in some of the basic books in the field, but all of the reference's I've been able to locate don't go into specifics of how to measure the quality of random numbers. Unless some measurements are made, you can't really be sure that those /dev/mem MD5 hashes don't come up the same 10%, 30%, or more of the time. It seems that a lot of assumptions are being made about what is good and what isn't. I plan to build a hardware random number generator and I have a couple of different circuits to do it, but I've heard some comments about some types of noise not being "good" cryptographically. -- Jeremy Porter ------------- Systems Engineering -------- Dell Computer Corp. ------ jerry(a)terminus.us.dell.com ---- --- 70 4F BD AE 6D E9 D2 66 48 18 8B E7 64 7F 59 8F --- Support your Second Amendment rights to encryption technology.

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soundfile stego
by jel＠sutro.SFSU.EDU 17 Dec '03

17 Dec '03

>> Also, I am told that humans have a tough time identifying >> the phase of the frequency components of the sounds they >> identify. So one could hide date in the phase relationships >> among the frequency components of, say, recorded speech. > >This sounds interesting. How about detection, how will some >random phase relationships stand out against normal phase of >various frequencies? I suspect that the unusual phase relationships would stick out, to anyone looking at the speech with,say, an oscilliscope. Eg, a squarewave would look pretty mangled if you shifted its component frequencies by some random amount, even though a human being might not be able to detect the difference between a squarewave, and a component-frequency shifted squarewave. On the other hand, how often does speech over some electronic medeum actually get analyzed this deeply?

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A change of pace
by Anonymous 17 Dec '03

17 Dec '03

Newsgroups: comp.org.eff.talk From: strnlght(a)netcom.com (David Sternlight) Subject: Re: EFF Op-Ed from the NY Times Message-ID: <strnlghtCHBurB.7on(a)netcom.com> Reply-To: david(a)sternlight.com (David Sternlight) Organization: DSI/USCRPAC References: <199311301632.LAA28210(a)eff.org> Date: Tue, 30 Nov 1993 23:04:21 GMT In article <199311301632.LAA28210(a)eff.org>, Stanton McCandlish <mech(a)eff.org> wrote: >From the New York Times Op-Ed Page, Wednesday, November 24, 1993 > >A Superhighway Through the Wasteland? > By Mitchell Kapor and Jerry Berman [Proposal for new laws to regulate the information highway omitted] Like most elitists and autocrats, eff's leaders believe in government intervention for the things they like (this topic) but not for the things they don't (Clipper). They believe in the private sector unrestricted for things they like (cryptography) but not for the things they don't (the information highway). David -- David Sternlight When the mouse laughs at the cat, there is a hole nearby.--Nigerian Proverb

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re: Big Brother/Bank Acco
by Duncan Frissell 17 Dec '03

17 Dec '03

M >Given the material in the WiReD 1.6 article, how likely is it that a M >true anonymous digital cash system would be allowed? I know, I know; M >there's "no way to prevent it"; however, I think that concept is M >based on the premise that the Government proceeds rationally. The East German government did not "proceed rationally" and yet is no longer with us. M >If somebody with an axe to grind gets hold of the "kidnapped baby" M >scenario described in _Applied_Cryptography_, plenty of public M >outrage and indignation could be generated. To what end. We have had the Kiddie Porn Over the Nets story of the Day every day for the last six months in the US and the UK. Have the nets been shut down? With the clearance rate for *murders* in NYC falling down towards 30%, I doubt if we have much to worry about for our minor "crimes." M >Go on, reassure me that "all is well". All is as well as can be extected and much better than we used to fear. DCF "I never expected to live to see the Death of Communism" -- Friedrich Hayek a few months before his death (and a few months after the SU's death. --- WinQwk 2.0b#1165

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Crypto Anarchy, the Gover
by Duncan Frissell 17 Dec '03

17 Dec '03

T >You mean, how likely is that the government will allow a system that T >makes taxation almost impossible, that enables black markets, that T >facilitates the transfer of illegal information, and that basically T >nukes the present arrangement? T > T >I don't think they'll "allow" it. But this doesn't mean it won't T >happen. For all of you who didn't hear my talk at ECFP '93 in London on the 20th (quite a few since there were fewer than 75 there) here is my conclusion which addresses this subject. **** "And what can we call this new form of social organization growing on the nets and in the modern fluid business environment? When two or more people can meet together and communicate freely and privately without interference by outsiders, they can trade -- they can form a market. If this trade on the nets is made free from even the possibility of external regulation, what we have is a free market and a free society." **** Remember kids God fights on the side with the heaviest artillery. Unless the government can come up with a way of blocking the above communication, it is SOOL. T >Imagine this: to get on the Data Superhighway, which will likely be T >the only major lines if the government succeeds in making it the T >mandatory standard, every data packet must have a "license plate." T >Don't laugh! The idea of a license plate on data packets is coming. It T >would provide the kind of traceability that control freaks like T >Detweiler claim to want So what if the car has a license plate if you can't tell what is in the car. No matter what happens telecoms will be cheap. Cheap means you can establish accounts and run a virtual network without disclosing the contents of the network messages or even that the network exists. You can hide your virtual network inside a much larger pseudo network which contains nothing interesting. DCF "The Trader swims in the sea of communications" -- Left out of Mao on Guerrilla Warfare because of editing error. --- WinQwk 2.0b#1165

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Re: Statistics of Low-Order Bits in Images
by kqb＠whscad1.att.com 17 Dec '03

17 Dec '03

Several people are attempting to create an algorithm to mask the presence of a steganized encrypted message in the least significant bits of an image. Don't forget that no matter how fancy your algorithm or how closely you mask your steganography with a model of what the statistics of an ordinary image look like, you have to assume that your opponent also knows your steganization algorithm, including your masking technique. (Otherwise you are just relying on security through obscurity.) This leaves you with three problems: (1) your opponent may have a much better model of an ordinary image than you do, and still be able to discern the existence of masked steganography, (2) since your opponent knows your steganization algorithm, he/she can look for any "signature" that your steganography masking model leaves, and (3) your opponent can "desteganize" all your images and check their statistics for deviations from the statistics for "desteganized" ordinary images. Resolving problems (1) and (2) requires a lot of work constructing good models. Resolving problem (3) requires, I think, a modeling function for steganography that is invertible only with a secret key. (Otherwise, your opponent could desteganize your image and find a uniform random distribution, which indicates an encrypted message.) Since this type of function is, to my knowledge, not well-developed, don't expect it to be secure. Thus, if breaking it could compromise your secret key for desteganization, then don't use the same public/private key pair for both encryption and steganography. Kevin Q. Brown INTERNET kqb(a)whscad1.att.com or kevin_q_brown(a)att.com

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Re: Entropy, Randomness, etc.
by collins＠newton.apple.com 17 Dec '03

17 Dec '03

Good questions. >My understanding of a random number is a number is generated from >two or more unrelated events. No. This may be one general category of ways to manufacture random numbers, but specifically a random number is just an arbitrary number typically drawn from a sequence of independent arbitrary numbers. The quality of 'randomness' is a measure of the independence of the elements in the stream. Therefor, there is no such thing as a random number except as an element of a sequence or other context from which to establish independence. >In order for this number to be most useful cryptographically, it needs >a even distribution. No. In order for this number to be cryptographically useful, it must cost more to guess the number (perhaps knowing the numbers that came before) than the reward for guessing it correctly. It happens that non-flat distribution of a sequence is a lever for cheaper guessing, thus flat distribution is natural characteristic of high-quality random sequences. >Does this make this distribution a gaussian distribution? No. Gaussian (a.k.a. 'normal') distribution is the bell curve (and clearly indicates a relation between samples). Math texts describing this distribution often use the phrase 'distribution of some random variable x', by which they in fact mean 'distribution of samples from a varying source'. >Also how are these statistical measurements done? See Knuth, "The Art of Computer Programming", Volume 2: Seminumerical Algorithms, Chapter 3: Random Numbers. >Is it as simple as a histogram? Yes. >Are we talking frequency analysis with FFTs and >more advanced things? Yes. >How do we measure the entropy of a random number, or a series of >random numbers? Ah. Now we're talking. Entropy is closely related but not equal to 'randomness'. Entropy is a measure of information often expressed as the fraction of information-size to data-size. Randomness is a measure of unpredictability. A sufficiently random sequence will be of very high entropy from the perspective of the 'guesser', though not necessarily from the that of the generator (e.g. a PRNG). The best way to measure entropy (if that is what you want to measure), is to build a sufficiently powerful Markov model, or the equivalent, to predict the sequence, and treat it like a compressor. The number of bits output is the entropy of the sequence with respect to that model. If you can't build a model as smart as your presumed attackers (as smart as them, not as smart as any model they might build), then you will have to use more tests to assure yourself of indepence of elements in the sequence (see Knuth, et al). In practice however, most of these methods represent very low bars over which any RNG _must_ jump, and which often poor ones can. Most RNGs are broken by understanding how they work, and exploiting weaknesses in their construction and context (e.g. poor 'seed' selection). >Have people on the list done this, or is this still in the range of >people that do math and number theory for a living? Yes, and Yes. >These topics are probably covered in some of the basic books in the field, >but all of the reference's I've been able to locate don't go into >specifics of how to measure the quality of random numbers. See Knuth. >Unless some measurements are made, you can't really be sure that those >/dev/mem MD5 hashes don't come up the same 10%, 30%, or more of the time. >It seems that a lot of assumptions are being made about what is good and >what isn't. You should be exactly as paranoid as it is cost effective to be. Hope this helps. Scott Collins | "Few people realize what tremendous power there | is in one of these things." -- Willy Wonka ......................|................................................ BUSINESS. voice:408.862.0540 fax:974.6094 collins(a)newton.apple.com Apple Computer, Inc. 5 Infinite Loop, MS 305-2B Cupertino, CA 95014 ....................................................................... PERSONAL. voice/fax:408.257.1746 1024:669687 catalyst(a)netcom.com

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Statistics of Low-Order Bits in Images
by jazz＠hal.com 17 Dec '03

17 Dec '03

>Sounds like the simple solution is for people everywhere to replace >the low order bits of all of their pictures with good random noise. You're kidding, right? Image processing software, and music processing equipment, are designed to get the maximum performance out of the storage medium. I find it pretty unlikely that any developer of image processing tools is going to deliberately drop one bit of precision off each n-bit unit; sheesh, image files are big enough without software deliberately wasting bits. As for introducing noise into the low-order bit of music CDs, definitely not; the trend is towards equipment that can extract the last dribble of information from well-recorded sources, and towards recording equipment that can meaningfully record every bit of every word. Why do you think there are 64x-oversampling players and the like? Eric's right; you'll have to build your own tools to make things noisy, as the trend elsewhere is to make things unnoisy. On the other hand, have you looked at the new mini-disc technology? That stuff already introduces audio compression, and the bits on a minidisc should be pretty high in entropy; of course, twiddling bits in a compressed audio recording may have dramatic effects on sound... Jason

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dithering, repudiable steganography
by jel＠sutro.SFSU.EDU 17 Dec '03

17 Dec '03

REPUDIABLE STEGANOGRAPHY I have a book (unfortunately not with me now) describing the format of data on music CDs. It seems that there is a kind of objectionable, heard noise in digital recordings called granulation noise. This is peculiar to digital; analog recording doesn't have this problem. Granulation noise manifests itself at low amplitudes, when the signal being represented is just at the resolution of the digital sampling. For example, if the signal is a sinusoid with a peak-to-peak amplitude represented by just a little greater than one bit difference in each sample. The problem is, the sampled sinusoid sounds just like a square wave when it is played back. Input, the signal: +--------------------------------------------------------------------- 2 | | xxx xxx | xx xx xx xx | x x x x 1 | x x x x | x x x x | x x x x | x x x x 0 +x-----------------x-----------------x-----------------x-------------- | x x x | x x x | x x x -1 | x x x x | x x x x | xx xx xx xx | xxx xxx -2 | +--------------------------------------------------------------------- Output, the digitized, sampled signal: +--------------------------------------------------------------------- 2 | | | | xxxxxxxxxxx 1 | xxxxxxxxxxx | | | 0 +xxxx-----------xxxx-----------------xxxx-----------xxxx-------------- | | | -1 | xxxx xxxx xxxx | | | -2 | xxxxxxxxx xxxxxxxxx +--------------------------------------------------------------------- This introduces (would introduce) lots of strong harmonics, making a very quiet flute, say, sound very unflutelike. The people who make commercial CDs get around this problem with a technique called dithering. They add to each sample a number from {-2, -1, 0, 1 2}, picked randomly. I.e., they randomly scramble the low few bits of each sample. The interesting thing about this is that, while it obviously degrades the signal, the result sounds better to human ears! It solves the problem of granulation noise. (The noisy flute sounds better than the clear but mangled squarewave thing the flute sounds like through the granulation noise). Of course there is something like 93 db dynamic range on a CD, so the dither hardly makes a dent in the usual sound quality -- it's only there to solve the granulation noise problem, which is only a problem at very low signal strengths. The only requirement for the dither bits is that they be such that they sound random, like noise. But any random source of bits with this property would work just as well for dithering. In particular, let's suppose you have an encrypted file, represented as a sequence of symbols, each of which has exactly 5 values it can assume. Musically, this would sound exactly like noise :-) . So *this* file could be used to dither an audiofile, instead of the "real" random values currently used. I guess what I really mean to say is that this insures that the low bit in a dithered file is *really* random; hence could be replaced with a bit from your encrypted file. Moreover, such a dithered audio file has some nice steganographic properties. 1) Repudiability. Under the assumption that the encrypted file cannot be cracked without the possession of the key to the file (which the owner of the steganographically-injected audio file has but claims ignorance of), the dither *really does* look like genuine, random dither. She can claim that the file is in fact a recording of the minutes of the last cypherpunks meeting, or a 3 hour concert that she taped off the radio, and no TLA can prove otherwise. Usually, a steganographically hidden datum (a microdot, invisible ink, etc.) doesn't have this property. 2) Zero storage requirements. This follows from 1), really. If you hide data in the unused parts of the last blocks on disk in a disk file, or in a hidden partition, the secrecy of the data (the "steganographic integrity"?) depends on the enemy not knowing or suspecting the existence of the data. PROBLEMS: You wouldn't be able to hide anything in your private copy of Michael Jackson's Thriller; the enemy could simply compare your copy with the standard copy, making the differences (the hidden file) stand out. Unless you were Warner Brothers, in which case you could just steganographically-inject ALL copys of Thriller with the secret file. This would make storage of the hidden file trivial. You could get a copy from the nearest Wherehouse. [I don't know if W.B in fact publishes Thriller; it's just an example] I wonder if CD pulishers know that they could make some money on the side by hiding data for people in their thousands of CDs? Anyway, while I don't know the format for DAT, I suspect there is some point where the sound signal is dithered to mask the granulation noise, and at this point Alice with information to hide could inject her file. Do digital pictures employ dithering to prevent aliasing? I think so. --John. jel(a)sutro.sfsu.edu

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soundfile stego
by jel＠sutro.SFSU.EDU 17 Dec '03

17 Dec '03

You know, you don't have to think of somehow modifying a file pointwise in the time domain. How about this, to stego a sound file: Do an FFT of the *entire* file. Assuming the file is two hours = 7200 seconds, the frequency res of the transformed file will be about 140 microhertz. Pick a band that humans don't usually pay much conscious attention to when they hear music; say 18 KHz through 19.5 KHz. Replace the low bit in each of these frequency space samples (there are 1500 / 0.000140 ~= 1E7 such samples) with the stego data. Inverse transform the modified, frequency space representation of the file back into the time domain, and voila! I suspect you would not be able to tell the difference from the original with your naked ears. But this is not repudiable; I suspect the spectrum of the file would look artificial. xxxxxxxxxxxxxxxxxxxx Also, I am told that humans have a tough time identifying the phase of the frequency components of the sounds they identify. So one could hide date in the phase relationships among the frequency components of, say, recorded speech.

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