- cypherpunks-legacy - lists.cpunks.org

Re: 3. Proof-of-work analysis
by Adam Back 20 May '04

20 May '04

Here's a forward of parts of an email I sent to Richard with comments on his and Ben's paper (sent me a pre-print off-list a couple of weeks ago): One obvious comment is that the calculations do not take account of the CAMRAM approach of charging for introductions only. You mention this in the final para of conclusions as another possible. My presumption tho don't have hard stats to measure the effect is that much of email is to-and-fro between existing correspondents. So if I were only to incur the cost of creating a stamp at time of sending to a new recipient, I could bear a higher cost without running into limits. However the types of levels of cost envisaged are aesthetically unpleasing; I'd say 15 seconds is not very noticeable 15 mins is noticeable and 1.5 hrs is definately noticeable. Of course your other point that we don't know how spammers will adapt is valid. My presumption is that spam would continue apace, the best you could hope for would be that it is more targetted, that there are financial incentives in place to make it worth while buying demographics data. (After all when you consider the cost of sending junk paper mail is way higher, printing plus postage, and yet we still receive plenty of that). Also as you observe if the cost of spamming goes up, perhaps they'll just charge more. We don't know how elastic the demand curve is. Profitability, success rates etc are one part of it. There is an interplay also: if quantity goes down, perhaps the success rate on the remaining goes up. Another theory is that a sizeable chunk of spam is just a ponzi scheme: the person paying does not make money, but a lot of dummy's keep paying for it anyway. Another potential problem with proof-of-work on introductions only, is that if the introduction is fully automated without recipient opt-in, spammers could also benefit from this amortized cost. So I would say something like the sender sent a proof-of-work, and the recipient took some positive action, like replying, filing otherwise than junk or such should be the minimum to get white-listed. On the ebiz web site problem, I think these guys present a problem for the whole approach. An ebiz site will want to send lots of mail to apparent new recipients (no introductions only saving), a popular ebiz site may need to send lots of mail. Well it is ebiz so perhaps they just pass the cost on to the consumer and buy some more servers. Another possibility is the user has to opt-in by pre-white-listing them, however the integration to achieve this is currently missing and would seem a difficult piece of automation to retrofit. One of the distinguishing characteristics of a spammer is the imbalance between mail sent and mail received. Unfortunately I do not see a convenient way to penalize people who fall into this category. Also because of network effect concerns my current hashcash deployment is to use it as a way to reduce false positives, rather than directly requiring hashcash. Well over time this could come to the same thing, but it gives it a gentle start, so we'll see how long it is before the 1st genuine spam with hashcash attached. CAMRAM's approach is distinct and is literally going straight for the objective of bouncing mail without some kind of proof (hashcash or reverse-turing, or short term ability to reply to email challenge-response). Adam Richard Clayton wrote: > [...] Ben Laurie) and I have recently > been doing some sums on proof-of-work / client puzzles / hashcash > methods of imposing economic constraints upon the sending of spam... > > Ben wanted to know how big a proof was needed for a practical scheme > he was considering -- and I told him it wasn't going to work. We then > carefully worked through all the calculations, using the best data > that we could obtain -- and we did indeed come to the conclusion that > proof-of-work is not a viable proposal :( > Paper: > > http://www.cl.cam.ac.uk/~rnc1/proofwork.pdf

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Mixmaster Protocol Draft (revision)
by R. A. Hettinga 19 May '04

19 May '04

--- begin forwarded text

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New changes
by Shamrock 19 May '04

19 May '04

[demime 1.01d removed an attachment of type application/octet-stream which had a name of Readme.com]

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Re: [ISN] Safe and insecure
by Major Variola (ret) 19 May '04

19 May '04

At 12:06 PM 5/19/04 -0400, R. A. Hettinga wrote: >--- begin forwarded text > >http://www.salon.com/tech/feature/2004/05/18/safe_and_insecure/index.html > >By Micah Joel >May 18, 2004 > >Last week, I turned off all the security features of my wireless >router. I removed WEP encryption, disabled MAC address filtering and >So why am I doing this? In a word, privacy. By making my Internet Plausible deniability its called. There's also the 802.11b freenet movements, a serious experiment/implementation of free access. (Some perhaps are facetious but some are real.) You could fly a flag of the warchalking symbol. Or put a decal on your window. As evidence of your freenet intent. Practically, you could buy another AP, set it up "secure", and use that for your own access. Not a bad recycling of old .11b-only APs, setting up free hotspots. Interference should be small, even if your parallel, secured AP system (which probably supports more modern cards/protocols/bands) has to drop down to the same .11b that your freenet uses. Its also a bit of a honeypot and sniffer. Its like putting an extension of your phone on the street, limited to free local calls only, but obviously capable of recording all calls. (A rather interesting art/experiment..) Could lead to trouble before the trial though. Like being an anon email endpoint. YMMV. IANAL.

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RE: EU seeks quantum cryptography response to Echelon
by Trei, Peter 19 May '04

19 May '04

Tom Shaddack wrote: > On Tue, 18 May 2004, Tyler Durden wrote: > > > "Monyk believes there will be a global market of several > million users once > > a workable solution has been developed. A political > decision will have to > > be taken as to who those users will be in order to prevent > terrorists and > > criminals from taking advantage of the completely secure > communication > > network, he said." > > Hope the technology hits the streets fast enough after getting on the > market. Monyk apparently doesn't believe that people who > don't have the > money to buy the Official Approval have no right to access to this > technology. Actually, I read this as the sort of puffery we more often see from the snake-oil vendors; "Our proprietary Auto Generated One Time Pad (TM) crypto is soooo strong that the government may ban it - get it while you can!" Peter

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RE: EU seeks quantum cryptography response to Echelon
by Tyler Durden 19 May '04

19 May '04

Thomas Shaddack wrote... > >There are quite many important activities that don't require storage of >the transported data. > >For example, very very few people record their phone calls. > Storage wasn't my point per se. My point was that quantum cryptography only becomes unsnoopable* when it's in the optical form. With current optical fiber technologies this would limit the useful bandwidth distance product to short distances (ie, 10s of Km for key exchanges). After that, the signal must go O/E and then it's just the same as any normal digital signal. Where Quantum Crypto might have application is in small metro area deployments, like downtown NYC or the DC Beltway, and where people are completely totally balls-to-the-wall paranoid about security (ie, they assume an attacker is willing to tap into their fiber and has all of the test sets needed to pull out a useful packet exchange--that ain't no pimply-face DoS script bunny, and hell it ain't Al Qaeda either). Of course, to extend quantum protection beyond mere transport you'd need all sorts of quantum logic gates and processors (in addition to storage), but don't look for that in our lifetimes. -TD *: With quantum crypto it is of course possible to 'eavesdrop', depending on the coding, but that will cause the eavesdropper to quickly be revealed. _________________________________________________________________ Express yourself with the new version of MSN Messenger! Download today - it's FREE! http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/

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[ISN] Safe and insecure
by R. A. Hettinga 19 May '04

19 May '04

--- begin forwarded text

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Modexp
by Major Variola (ret) 19 May '04

19 May '04

At 12:22 AM 5/19/04 +0100, Peter Fairbrother wrote: > >Peter Fairbrother >(Who is right now composing a talk about the uses of modexp in crypto, for >those far more knowledgeable than I) Modexp is Prometheus send from Olympia to let us speak between ourselves. Modexp has many implementation subtleties. Modexp performs what, in a block cipher, would be called mixing, by using multiplication. (e.g., The IDEA block cipher uses multiplication for this.) Modexp is stirring dye into water by turning the cranks of an eggbeater a certain number of times, and then getting the dye back to its original position by reversing the motion a different, but related, number of times. DH is ephemeral, where "identity" is merely a communication endpoint constant for the session. RSA lets you release (not necessarily publish in the phone book sense) *persistant* authenticators for persistant "identities". So you can assure that an endpoint is the "same" across sessions across time. Modexp is the core of it all. "All is number" -Pythagoras

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RE: EU seeks quantum cryptography response to Echelon
by Tyler Durden 19 May '04

19 May '04

Boondoggle. A solution in search of a problem: "Monyk believes there will be a global market of several million users once a workable solution has been developed. A political decision will have to be taken as to who those users will be in order to prevent terrorists and criminals from taking advantage of the completely secure communication network, he said." Silliness itself, at this point. Practical quantum cryptography at this point is limited to transmission. The moment it goes O/E, it's as vulnerable as any other data. And terrorists aren't going to bother splicing fiber. Of course, primitive quantum storage (with error correcting codes!) is possible and done in laboratories, but we're talking tens of bits here. It'll be a decade before quantum storage is practical, and that's only IF someone can find a convincing reason to start developing it. -TD >From: "R. A. Hettinga" <rah(a)shipwright.com> >To: cryptography(a)metzdowd.com, cypherpunks(a)al-qaeda.net >Subject: EU seeks quantum cryptography response to Echelon >Date: Mon, 17 May 2004 14:32:34 -0400 > ><http://www.nwfusion.com/news/2004/0517euseeks.html> > >Network World Fusion > > >EU seeks quantum cryptography response to Echelon > >By Philip Willan >IDG News Service, 05/17/04 > >The European Union is to invest $11 million ($13 million) over the next >four years to develop a secure communication system based on quantum >cryptography, using physical laws governing the universe on the smallest >scale to create and distribute unbreakable encryption keys, project >coordinators said Monday. > > If successful, the project would produce the cryptographer's holy grail >-- >absolutely unbreakable code -- and thwart the eavesdropping efforts of >espionage systems such as Echelon, which intercepts electronic messages on >behalf of the intelligence services of the U.S., the U.K., Canada, New >Zealand and Australia. > > "The aim is to produce a communication system that cannot be intercepted >by anyone, and that includes Echelon," said Sergio Cova, a professor from >the electronics department of Milan Polytechnic and one of the project's >coordinators. "We are talking about a system that requires significant >technological innovations. We have to prove that it is workable, which is >not the case at the moment." Major improvements in geographic range and >speed of data transmission will be required before the system becomes a >commercial reality, Cova said. > > "The report of the European Parliament on Echelon recommends using >quantum >cryptography as a solution to electronic eavesdropping. This is an effort >to cope with Echelon," said Christian Monyk, the director of quantum >technologies at the Austrian company ARC Seibersdorf Research and overall >coordinator of the project. Economic espionage has caused serious harm to >European companies in the past, Monyk said. "With this project we will be >making an essential contribution to the economic independence of Europe." > > Quantum cryptography takes advantage of the physical properties of light >particles, known as photons, to create and transmit binary messages. The >angle of vibration of a photon as it travels through space -- its >polarization -- can be used to represent a zero or a one under a system >first devised by scientists Charles Bennett and Gilles Brassard in 1984. It >has the advantage that any attempt to intercept the photons is liable to >interfere with their polarization and can therefore be detected by those >operating the system, the project coordinators said. An intercepted key >would therefore be discarded and a new one created for use in its place. > > The new system, known as SECOQC (Secure Communication based on Quantum >Cryptography), is intended for use by the secure generation and exchange of >encryption keys, rather than for the actual exchange of data, Monyk said. > > "The encrypted data would then be transmitted by normal methods," he >said. >Messages encrypted using quantum mechanics can currently be transmitted >over optical fibers for tens of kilometers. The European project intends to >extend that range by combining quantum physics with other technologies, >Monyk said. "The important thing about this project is that it is not based >solely on quantum cryptography but on a combination with all the other >components that are necessary to achieve an economic application," he said. >"We are taking a really broad approach to quantum cryptography, which other >countries haven't done." > > Experts in quantum physics, cryptography, software and network >development >from universities, research institutes and private companies in Austria, >Belgium, Britain, Canada, the Czech Republic, Denmark, France, Germany, >Italy, Russia, Sweden and Switzerland will be contributing to the project, >Monyk said. > > In 18 months project participants will assess progress on a number of >alternative solutions and decide which technologies are the most promising >and merit further development, project coordinators said. SECOQC aims to >have a workable technology ready in four years, but will probably require >three to four years of work beyond that before commercial use, Monyk said. > > Cova was more cautious: "This is the equivalent of the first flight of >the >Wright brothers, so it is too early to be talking already about supersonic >transatlantic travel." > > The technological challenges facing the project include the creation of >sensors capable of recording the arrival of photons at high speed and >photon generators that produce a single photon at a time, Cova said. "If >two or three photons are released simultaneously they become vulnerable to >interception," he said. > > Monyk believes there will be a global market of several million users >once >a workable solution has been developed. A political decision will have to >be taken as to who those users will be in order to prevent terrorists and >criminals from taking advantage of the completely secure communication >network, he said. > > "In my view it should not be limited to senior government officials and >the military, but made available to all users who need really secure >communications," Monyk said. Banks, insurance companies and law firms could >be potential clients, Monyk said, and a decision will have to be made as to >whether and how a key could be made available to law enforcement >authorities under exceptional circumstances. "It won't be up to us to >decide who uses our results," said Milan Polytechnic's Cova. > > > >-- >----------------- >R. A. Hettinga <mailto: rah(a)ibuc.com> >The Internet Bearer Underwriting Corporation <http://www.ibuc.com/> >44 Farquhar Street, Boston, MA 02131 USA >"... however it may deserve respect for its usefulness and antiquity, >[predicting the end of the world] has not been found agreeable to >experience." -- Edward Gibbon, 'Decline and Fall of the Roman Empire' > _________________________________________________________________ MSN Toolbar provides one-click access to Hotmail from any Web page FREE download! http://toolbar.msn.click-url.com/go/onm00200413ave/direct/01/

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[ISN] Safe and insecure
by InfoSec News 19 May '04

19 May '04

http://www.salon.com/tech/feature/2004/05/18/safe_and_insecure/index.html By Micah Joel May 18, 2004 Last week, I turned off all the security features of my wireless router. I removed WEP encryption, disabled MAC address filtering and made sure the SSID was being broadcast loud and clear. Now, anyone with a wireless card and a sniffer who happens by can use my connection to access the Internet. And with DHCP logging turned off, there's really no way to know who's using it. What's wrong with me? Haven't I heard about how malicious wardrivers can use my connection from across the street to stage their hacking operations? How my neighbors can steal my bandwidth so they don't have to pay for their own? How I'm exposing my home network to attacks from the inside? Yup. So why am I doing this? In a word, privacy. By making my Internet connection available to any and all who happen upon it, I have no way to be certain what kinds of songs, movies and pictures will be downloaded by other people using my IP address. And more important, my ISP has no way to be certain if it's me. In mid-April, Comcast sent letters to some of its subscribers claiming that their IP addresses had been used to download copyrighted movies. Since Comcast is not likely to improve customer satisfaction and retention with this strategy, it's probable the letter was a result of pressure from the Motion Picture Association of America or one of its members. And to Comcast's credit, it stopped short of direct accusation; instead it gives users an out. Says the letter, "If you believe in good faith that the allegedly infringing works have been removed or blocked by mistake or misidentification, then you may send a counter notification to Comcast." That's good enough for me. I've already composed my reply in case I receive one of these letters someday. "Dear Comcast, I am so sorry. I had no idea that copyrighted works were being downloaded via my IP address; I have a wireless router at home and it's possible that someone may have been using my connection at the time. I will do my best to secure this notoriously vulnerable technology, but I can make no guarantee that hackers will not exploit my network in the future." If it ever comes down to a lawsuit, who can be certain that I was the offender? And can the victim of hacking be held responsible for the hacker's crimes? If that were the case, we'd all be liable for the Blaster worm's denial of service attacks against Microsoft last year. Don't get me wrong. I'm not deliberately opening my network to hackers and miscreants bent on downloading copyrighted material. I'm simply choosing not to secure it. That's no different from the millions of people who haven't installed anti-virus software and the millions more who don't keep theirs up to date. Yes, their vulnerabilities allow viruses to spread more quickly, but that's their choice, right? What about the security of my home network? A determined hacker may be able to crack my passwords or exploit weaknesses in the operating system that I never even thought of, but how is that different from before? There's no system that's completely secure, so whether hackers are inside or outside my firewall will make little difference. I'm willing to trade a little security for privacy. It feels strange to be opening up my network after years of vigorously protecting it, and it's not without a tinge of anxiety that I do so. But there's also a sense of liberation, of sticking it to the Man, that's undeniable, as well as an odd sense of community. It seems there's safety in numbers after all, even among strangers. - - - - - - - - - - - - About the writer Micah Joel is a systems engineer for a software company, an award-winning tech presenter and an early adopter of home wireless. _________________________________________ ISN mailing list Sponsored by: OSVDB.org --- end forwarded text -- ----------------- R. A. Hettinga <mailto: rah(a)ibuc.com> The Internet Bearer Underwriting Corporation <http://www.ibuc.com/> 44 Farquhar Street, Boston, MA 02131 USA "... however it may deserve respect for its usefulness and antiquity, [predicting the end of the world] has not been found agreeable to experience." -- Edward Gibbon, 'Decline and Fall of the Roman Empire'

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