Re: Encrypted search?
At 10:11 AM +0100 9/22/03, Dave Howe wrote: Tyler Durden wrote: When the search is performed, the "stupid" thing to do (I think...someone correct me) is to take the user's ID, encrypt it, and then determine if matches an encypted member of the list (and I don't see encrypted each entry individually as a desirable thing). I am assuming that this allows a savvy user to reverse-engineer the encryption. What you do is hash the ID, then compare it to the list of hashed entries, using the ID as the key to decrypt the data associated with that entry while that isn't subject to reverse engineering, the abuse it *is* open to is random guessing of IDs (every "success" gives someone else's record, with failures having no penalty) Adding a password (and combining it with the ID to give your key) will address some of that, but really you need to encrypt each entry individually to prevent someone simply decompiling your code and obtaining your full data list. Another option is one I don't have the background at this stage to understand. Let's assume the entire list has been encrypted in one shot. Is there some function such that when this encrypted list is convolved with the user ID a "Yes" or "no" can be obtained (indicating presence or absence from the list)? no. if you trial encrypt the sample ID for comparison, you hand them the key to the whole list. Yes, these are all good solutions. If you want a case study of how this might help a company like Amazon, go here: http://www.wayner.org/books/td/u1.php --- My new books: _Policing Online Games_ (http://www.wayner.org/books/pog/) _Java RAMBO Manifesto_ (http://www.wayner.org/books/rambo/)
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Lately, there has been some discussion on mailing lists and blogs about the fact that srcabmling the oredr of ltetres in Egnilsh deson't afefct raebditly. I decided to write some code to experiment with it. You can try out the Java applet here: http://www.wayner.org/books/discrypt2/wordsteg.php Source code is available protected by the LGPL. It builds upon an earlier experiment here: http://www.wayner.org/books/discrypt2/sorted.php Please write if you have questions, thoughts, comments, etc. Peter Wayner [EMAIL PROTECTED]
Searching for uncopyable key made of sparkles in plastic
Several months ago, I read about someone who was making a key that was difficult if not "impossible" to copy. They mixed sparkly things into a plastic resin and let them set. A camera would take a picture of the object and pass the location of the sparkly parts through a hash function to produce the numerical key represented by this hunk of plastic. That numerical value would unlock documents. This was thought to be very difficult to copy because the sparkly items were arranged at random. Arranging all of the sparkly parts in the right sequence and position was thought to be beyond the limits of precision for humans. Can anyone give me a reference to this paper/project? Thanks! -Peter
Re: Question on P=NP
At 8:55 AM -0800 12/1/02, Sarad AV wrote: hi, Is the problem P=NP or not 'Decidable'. I don't even think we know. I vaguely remember someone saying that it would be really fascinating if it turned out not to be decidable. -Peter
Re: Fwd: Re: Fwd: Book Review: Peter Wayner's "Translucent Databases"
I think Bob made some great points about my book, but it's clear that this debate is revolving around a few sentences in Bob's review. Perhaps he miscategorizes Brin, perhaps he doesn't. I haven't read _Transparent Society_ in some time. Still, it's important to realize that this isn't just a battle between the state and its citizens. Encryption can provide a practical tool and a great option for the data management engineers. Brin has a good point about the value of openness, but I'm sure he doesn't extend it to things like people's credit card numbers. Brin would probably be interested in the book and the way it leaves some things in the clear. It's all about translucency, which is, after all, partially transparent. The glass is half empty or full. So maybe there's something in common here? The right use of encryption (and any anonymity that comes along with it) can protect businesses, customers, clients, employees and others. I'm sure it might also be used to by a few elites to avoid scrutiny, but that doesn't have to be the case. For me, the mathematics of on-line anonymity are essential parts of on-line security. While I think that there are plenty of personal and emotional reasons to embrace anonymity, one of the best is the higher amount of security the systems offer. Simply put, identity-based systems are more fragile because identity theft is so easy. Systems designed for anonymity avoid that weakness because they're designed, a priori, to work without names. So I think they're just bound to be a bit safer. It should be noted that the anonymous techniques developed by Chaum, Brands and others do not have to be used to avoid scrutiny. You can always tack on your true name in an additional field. To me, the systems just avoid relying on the the name field to keep people honest. I'm glad Bob sees the resonance between _Translucent Databases_ and the world of cypherpunk paranoia, but I would like to avoid a strong connection. It's not that there's no relationship. There is. But the book is meant to be much more practical. It explores how to use the right amount of encryption to lock up the personal stuff in a database without scrambling all of it. In the right situations, the results can be fast, efficient, and very secure. So the techniques are good for the paranoids as well as the apolitical DBAs who just want to do a good job. > > >>It is particularly dishonest of a so-called reviewer not only to >>misinterpret and misconvey another person's position, but to abuse >>quotation marks in the way Robert Hettinga has done in his review of >>Translucent Databases By Peter Wayner. Openly and publicly, I defy >>Hettinga to find any place where I used the word "trust" in the fashion or >>meaning he attributes to me. >> >>In fact, my argument is diametrically opposite to the one that he portrays >>as mine. For him to say that 'Brin seems to want, "trust" of state >>force-monopolists... their lawyers and apparatchiks." demonstrates either >>profound laziness - having never read a word I wrote - or else deliberate >>calumny. In either event, I now openly hold him accountable by calling it >>a damnable lie. This is not a person to be trusted or listened-to by >>people who value credibility. >> >>Without intending-to, he laid bare one of the 'false dichotomies" that >>trap even bright people into either-or - or zero-sum - kinds of >>thinking. For example, across the political spectrum, a "Strong Privacy" >>movement claims that liberty and personal privacy are best defended by >>anonymity and encryption, or else by ornate laws restricting what people >>may know. This approach may seem appealing, but there are no historical >>examples of it ever having worked. >> >>INdeed, those mired in these two approaches seem unable to see outside the >>dichotomy. Hettinga thinks that, because I am skeptical of the right >>wing's passion for cowboy anonymity, that I am therefore automatically an > >advocate of the left wing's prescription of "privacy through state >>coercive information management'. Baloney. A plague on both houses of >>people who seem obsessed with policing what other people are allowed to know. >> >>Strong Privacy advocates bears a severe burden of proof when they claim > >that a world of secrets will protect freedom... even privacy... better > >than what has worked for us so far - general openness. > > > >Indeed, it's a burden of proof that can sometimes be met! Certainly there >>are circumstances when/where secrecy is the only recourse... in concealing >>the
Re: sources on steganography
At 11:19 AM -0400 5/29/02, Hector Rosario wrote: >I am writing my dissertation on steganography. Basically I'm writing a >technical monograph that would be of use to undergraduate instructors. >What do you think are the best sources on steganography on >the Web? What about books other than Johnson, Katzenbeiser & Peticolas, >and the volumes covering the four international workshops on information >hiding. I know that my book, _Disappearing Cryptography_, is being used as a textbook in a few schools. It's a bit broader than the others because it uses a more inclusive view of the topic. You can read a bit more here: http://www.wayner.org/books/discrypt2/ The book on Watermarking by Cox et al is also very nice, although very focused and very detailed. -Peter
Still more steganography tools.
To help flog the second edition of Disappearing Cryptography and encourage a general education in things steganographic, I'm continuing to roll out Java applets on the book's website. This week I've added a few new features to last week's applet that let you hide information in the noise of an image. That is, replace the least significant bits of an image with either an ASCII text message or random data. You can replace anywhere between 1 to all 8 of the image's bit plane. I think it's amazing how much you can stuff in an image before it starts to degrade. The new features allow you to examine the least significant bits of an image. One option will delete the seven most significant bit planes and keep only the least. Another option lets you compare the most significant with the least, although it depends a great deal on the image. This experiment has its problems. Video cards don't always offer enough precision. You'll get more consistent results if you use a higher setting on your video card. The JPEG images don't have enough resolution. Also, this system relies upon 24-bit color, a file format that's rarely found in nature. More sophisticated systems can target compressed images. Try it here: http://www.wayner.org/books/discrypt2/bitlevel.php You can try earlier applets like this one for hiding information in the order of a list of items: http://www.wayner.org/books/discrypt2/sorted.php Or this one for hiding in the voice over to a baseball game: http://www.wayner.org/texts/mimic/ Source code protected by the GPL available for all of these. Just ask. You might also be interested in my other new book, Translucent Databases, for people who must guard sensitive information in their database: http://www.wayner.org/books/td/
More steganography tool fallout from Disappearing Cryptography
To help flog the second edition of Disappearing Cryptography and encourage a general education in things steganographic, I'm continuing to roll out Java applets on the book's website. The latest applet lets you hide information in the noise of an image. That is, replace the least significant bits of an image with either an ASCII text message or random data. You can replace anywhere between 1 to all 8 of the image's bit plane. I think it's amazing how much you can stuff in an image before it starts to degrade. This experiment has its problems. Video cards don't always offer enough precision. You'll get more consistent results if you use a higher setting on your video card. Also, this system relies upon 24-bit color, a file format that's rarely found in nature. More sophisticated systems can target compressed images. Try it here: http://www.wayner.org/books/discrypt2/bitlevel.php You can try earlier applets like this one for hiding information in the order of a list of items: http://www.wayner.org/books/discrypt2/sorted.php Or this one for hiding in the voice over to a baseball game: http://www.wayner.org/texts/mimic/ Source code protected by the GPL available for all of these. Just ask. You might also be interested in my other new book for people who must guard sensitive information in their database: http://www.wayner.org/books/td/
re: Satellite Hacking Article Now Free
At 3:12 PM -0700 5/1/02, [EMAIL PROTECTED] wrote: >Seems to me that oneof the keys to permanently unlocking sat TV is >to do away with the vendor's receiver. From my novice perspective, >it seems many or most of the attacks against pirate devices are >based on the assumption that the pirate must still have a set-top >box which is still, indirectly, under control of the service >provider (that is its unmodified). What if an affordable software >based radio replaced the set-top box and the smart card >functionality? It would seem to me that 3M (Three Musketeer) >attacks, wherein one or more legal purchasers of the service >broadcast in real-time the required stream decryption codes over >ICQ/IRQ to all the other SDR boxes. This must have been thought of >or already tried. What am I missing Peter? Nothing. I think that's correct. The only problem is broadcasting the keys is not simple. The latest systems change keys frequently-- as often as every 20 or 30 seconds I seem to remember. If you change the channel, you need a new key. It's not like the old days when the key changed daily or monthly. If you have such a service broadcasting the keys, it's not too hard to track you down. So I think it's not a practical solution. -Peter
Satellite Hacking Article Now Free
Last year I wrote a long piece about people hacking DirecTV satellite signals. Now I'm releasing it for free to the web with a couple of embedded ads for my latest books. If you're interested in a few clever people who find ways to defeat some of the best security systems available, you might want to read it. The link is at the top of my home page/blog: http://www.wayner.org/ If you can't find it there, try here: http://www.wayner.org/books/f7.pdf You are free to circulate this as long as you leave the ads for _Disappearing Cryptography_ and _Translucent Databases_ in place. Please be aware that there is a new legal climate in Canada, the hotbed for most of the public hacking. The Canadian Supreme Court effectively re-criminalized the behavior with a new decision last Friday, April 22. Before that date, the lower courts accepted the arguments of the pirates who claimed that the law didn't protect DirecTV because DirecTV wasn't legally broadcasting in Canada. This changes the legal equation, but it doesn't affect one of the major root causes of the piracy. Canadians who want to watch the better, cheaper American programming will still have no choice but to steal it. If you have thoughts, suggestions or pointers, please don't hesitate to contact me. Peter Wayner [EMAIL PROTECTED]
