Re: The Shining Cryptographers Net
On Thu, 18 Jan 2001 [EMAIL PROTECTED] wrote: Or does somebody have a good defense against this hyper-active attack? The only thing I can suggest would be if the rotation stations could somehow count or limit the number of photons going through so that they would know when there were extra. I think this is possible in theory; whether it can be done in practice is questionable. Hm? As far as I know there's no way to detect (count) a photon that doesn't affect its quantum state in some way that can be later detected. In this case, that's not an option, because you're trying to use the quantum state to transmit information. If you fiddle with it by trying to count photons, the information will change. Is there a detector that affects some *other* part of the Quantum state, and won't mess with the polarization? Another idea would be for the stations to actually absorb the photon in some manner that preserved its polarization, and then to re-emit it. These could be primed to pass only a single photon. Now you are talking serious voodoo. I don't think that this can be done this year. Maybe not this decade. Bear
Re: The Shining Cryptographers Net
At 02:04 PM 1/18/01 -0800, [EMAIL PROTECTED] wrote: the rotation stations could somehow count or limit the number of photons going through so that they would know when there were extra. I think this is possible in theory; Right, it is. Here's a Gedankenexperiment: temporarily trap the signal in a cylindrical waveguide resonator (organ pipe). The pressure on the end-caps is proportional to photon number and independent of polarization angle. From this we conclude we can measure number in a way that commutes with polarization. I went overboard when previously I said "any" attempt at integrity-checking would mess up the signal. Still, integrity-checking of a single photon would be hard. I don't think she could learn much with a single photon, I'm not so sure about that. Remember, photon counters (which measure A_dagger A) are not the only measuring devices in the world. There are also voltmeters (which measure A_dagger plus A). For low-amplitude analog signals, the voltmeter is vastly more informative. I have not yet cobbled up a believable apparatus for measuring the polarization angle of a single photon, but I don't think it would be terribly hard to do so.
Re: What's Wrong With Content Protection
John -- Great essay... thanks for replying at such length! I'm going to decline your (perhaps rhetorical) invitation to provide a devils-advocate counter-argument, because I'm not the right person to do so; I am far too liberal in my own views to be a fair representative of the "dark side". In any case, I was asking more for an education (which you have generously provided) than an argument. Cheers, Ron Rivest
Re: The Shining Cryptographers Net
Ray Dillinger wrote, quoting me: Another idea would be for the stations to actually absorb the photon in some manner that preserved its polarization, and then to re-emit it. These could be primed to pass only a single photon. Now you are talking serious voodoo. I don't think that this can be done this year. Maybe not this decade. Actually there is a report out just today that could be a big step towards this capability. From http://www.aip.org/physnews/update/521-1.html: For the first time, physicists in two separate laboratories have effectively brought a light pulse to a stop. In the process, physicists have accomplished another first: the non-destructive and reversible conversion of the information carried by light into a coherent atomic form. This experiment captures light and transforms it into an excited gas state, in a reversible way, so that the original light pulse can restored at a later time: Usually photons (the quanta of light) are absorbed by atoms, destroying the information carried by the light. With the present method, in principle, no information in the light pulse is lost. If this applies to the polarization information as well then it would be close to what I called for above. Then you'd still need some way to be able to distinguish how many photons' worth of energy you'd caught in your gas, or to limit the emission to only a single photon. If so then this would be a "single photon" filter. So perhaps the idea is not as far-fetched as it sounds. Hal
Re: Full text to the book ``Underground'' released.
The site below has been offline because of heavy traffic. Mirrors, in case you can't get through: http://www.attrition.org/ee/underground-book.zip http://www.politechbot.com/docs/underground.011800.txt.gz -Declan On Thu, Jan 18, 2001 at 08:31:03AM +1100, Julian Assange wrote: [More security than cryptography but I'm passing it along... --Perry] I very pleased to announce that thanks to Random House, Suelette Dreyfus and myself the complete and unabridged electronic text to our famed computer crime book ``Underground'' (approx 500 pp.) has been publically released. +-+ | Format | Name| Size (bytes) | |-| |-| | Text | underground.txt | 979993 | |-| |-| | Text, ZIP | underground.zip | 357915 | |-| |-| | Text, GZIP | underground.txt.gz | 355953 | |-| |-| | Text, BZIP2| underground.txt.bz2 | 265014 | |-| |-| | Palm Basic Doc | underground.pdb | 519140 | |-| |-| | Palm Teal Doc | underground-tealdoc.pdb | 520661 | +-+ The Palm formated files will allow you to read the book on a Palm Pilot and various other handheld machines. See http://www.underground-book.com/download.php3 Feel free to forward this message. Julian. -- Julian Assange|If you want to build a ship, don't drum up people |together to collect wood or assign them tasks and [EMAIL PROTECTED] |work, but rather teach them to long for the endless [EMAIL PROTECTED] |immensity of the sea. -- Antoine de Saint Exupery
3G crypto algorithms
Dear cryptographers, In contrast with GSM, the 3GPP organisation (responsible for 3G wireless phone standards) is making all of its documents public. However, the way in which these documents are made public is unlikely to result in immediate gratification for those who would just like to go in and look at the crypto algorithms. For that reason, I have undertaken to construct a Web page to help cryptographers learn about and study the crypto algorithms for 3G wireless phones. I believe that the algorithms will receive much more and better scrutiny if it is easy to find them (and other 3G documents that are relevant to them). This page can be found at http://www.research.att.com/~janos/3gpp.html Thank you for your attention! Janos A. Csirik. -- Janos A. Csirik, Mathematics Cryptography, ATT Labs - Research
Re: What's Wrong With Content Protection
John Gilmore wrote: Few or no manufacturers are willing to put ordinary digital audio recorders on the market -- you see lots of MP3 *players* but where are the stereo MP3 *recorders*? They've been chilled into nonexistence by the threat of lawsuits. The ones that claim to record, record only "voice quality monaural". Which is ironic, because there's any amount of free software out there that will do it. We don't need their steenkin' MP3 recorders. :-) Cheers, Ben. -- http://www.apache-ssl.org/ben.html "There is no limit to what a man can do or how far he can go if he doesn't mind who gets the credit." - Robert Woodruff
