January 1993 - cypherpunks-legacy

Re: bbs
by nowhere＠bsu-cs.bsu.edu 13 Jan '93

13 Jan '93

>So they are using a whole bunch of accounts in an effort to conceal their >identity? And they hope that one of the accounts will be approved >for full access to adult material, without the sysop really knowing >who they are? Yes, the intention is to get one approved without the SYSOP really knowing who he approves. >Do you always check the phone number supplied as part of the registration >process or wait until the user abuses the BBS? It seems that someone >could simply start taking names out of the phone book if he wanted to >conceal who he really is... I used to check phone numbers, now I only check those of users with strange names or wait until they abuse the system. The first thing I check when someone abuses my system is their identity. If it's fraudulent, I put the account in the system kill file and they can no longer login. I use a pretty good method for allowing access to adult areas. A consent form must be filled out and signed. Then it is mailed to me with a photocopy of the same person's driver's license (SSN can be blacked out, I'm not concerned with it). I file it away and give them access if it looks correct. Generally, I detect system abuse pretty soon after it occurs. Then, I handle the situation as quickly and efficiently as possible. The same user rarely tries it again. I did voice validate all of my users, but that got to be tedious, so I just check when something happens. Many BBS's require that they be able to call a user back directly before granting full access. This would not work over the Internet, a University modem pool like many were using here, or long distance for the cheap SYSOP. There are, however, a flurry of programs that perform "automatic call-back telephone number verification." Chael Hall -- Chael Hall nowhere(a)bsu-cs.bsu.edu, 00CCHALL(a)LEO.BSUVC.BSU.EDU, CHALL(a)CLSV.Charon.BSU.Edu (317) 285-3648 after 3 pm EST

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re: mental poker protocol
by Karl L. Barrus 13 Jan '93

13 Jan '93

Hal writes: >Am I missing something in the description of the protocol, or was the >actual protocol perhaps a little different than this? Oops. I typed too quickly; the posted protocol specified shuffling the entire deck to form message M3. Thus, each player draws from a full deck. While this isn't exactly poker, I'm still willing to play somebody. So Hal's right: the original protocol is different - it's not broken like the one I posted :-) The post to sci.crypt was in response to a bit commitment question. Here, players commit by making public their hashes. Later, everyone can verify when the messages are known. If anyone's interested, send me a notice to elee9sf(a)menudo.uh.edu. (The server for my other account is acting erratic and I'm considering moving my subscription). /-----------------------------------\ | Karl L. Barrus | | elee9sf(a)menudo.uh.edu | <- preferred address | barrus(a)tree.egr.uh.edu (NeXTMail) | \-----------------------------------/

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Mental poker.
by Hal 13 Jan '93

13 Jan '93

Mental poker protocols are notorious for having sometimes subtle weaknesses. I missed the posting on sci.crypt which Karl mentioned but his description of the protocol seems to have a flaw: > 4) B shuffles the remaining 47 cards, lists them by number, appends a > random bit stream to create M3, and computes the hash. B sends hash > MD5(M3) to A. > [...] > 6) B sends A M3 so A get get her cards. If B in step 6 sends A message M3, which lists the 47 cards left after B has chosen his 5 from the 52 they started with, then A will be able to see which 5 B chose; those are the 5 not listed in M3. Am I missing something in the description of the protocol, or was the actual protocol perhaps a little different than this? Hal Finney 74076.1041(a)compuserve.com

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mental poker
by Karl L. Barrus 13 Jan '93

13 Jan '93

Okay, anybody want to play mental poker with me??? A protocol involving bit committment was posted to sci.crypt recently, which we can use to play. There is an RSA protocol, but a commutative encryption/decryption is required, which I don't think PGP provides. So here is the protocol: 1) A shuffles cards, creates a message M1 that lists the cards by number. A appends a random bit stream, and computes the hash (using MD5). A sends hash MD5(M1) to B. 2) B composes message M2 that lists the cards he chooses by number. B appends a random bit stream, and computes the hash. B sends the hash MD5(M2) to A. 3) A sends B M1 so B can get his cards. 4) B shuffles the remaining 47 cards, lists them by number, appends a random bit stream to create M3, and computes the hash. B sends hash MD5(M3) to A. 5) A chooses cards by number, appends a random bit stream to create M4, and computes hash. A sends MD5(M4) to B. 6) B sends A M3 so A get get her cards. A and B can catch cheating by comparing the various message and hashes. Getting extra cards can be left as further extensions, as can multiple players (3 or more). Any takers? By the way, the hash function implementation I have is the sigfetch routine contained in tripwire. It includes md5, md4, md2, snefru, crc, and crc32. So before a game starts the players should verify their respective hashers. /-----------------------------------\ | Karl L. Barrus | | barrus(a)tree.egr.uh.edu (NeXTMail) | | elee9sf(a)menudo.uh.edu | \-----------------------------------/

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security of constructed addresses
by Karl L. Barrus 13 Jan '93

13 Jan '93

Alert! Hal Finney has alerted me to a problem with the way my script builds an anonymous remailer chain. Simply saving eachheader portion into a seperate file and running pgp on the pieces reveals each link in the chain. The solution (also from Hal Finney) is: hide the intermediate hops until they get to the machine that needs them. (machine1, encrypt1(machine2, encrypt2(machine3, encrypt3(user@dest)))) Here, the entire header is decrypted at each remailer, revealing the next destination to that remailer only. No peeking ahead! The only remailer that will be revealed is the first one, where mail has to be sent anyway. I'll rework the script, provide a ksh version, and write a little help file ASAP. /-----------------------------------\ | Karl L. Barrus | | barrus(a)tree.egr.uh.edu (NeXTMail) | | elee9sf(a)menudo.uh.edu | \-----------------------------------/

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Cascading aliases
by Hal 12 Jan '93

12 Jan '93

I think Matthew Rapaport's point is good that much of the trouble with the automatic assignment of aliases comes from the automatic mailing to the user of a new alias. Most of the remailing servers have a special address or command you can send meaning "assign me a new alias, and tell me what it is". Probably, as Matthew says, they should only mail back the newly assigned alias when one of these special commands is used. I'm still not convinced that automatic alias assignment should always be done when mail goes through a server from a new address. It seems like this might generate so many aliases that it would be too great a load on the servers, especially if remailers become more widely used. But it's hard to say how bad a problem this is. I feel that the main purpose of an anonymous address is to protect the anonymity of the person being addressed, not people who send to him. Just because a person chooses to be anonymous is no reason to expect that everyone who wants to talk to him also wants to be anonymous. I think it would be better to only provide anonymity when asked. Systems that do too much for people sometimes get in the way. Hal Finney 74076.1041(a)compuserve.com Distribution: Cypherpunks >INTERNET:cypherpunks@toad.com

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Crypto Bus to Winter Usenix in San Diego
by hugh＠domingo.teracons.com 12 Jan '93

12 Jan '93

[The Bays (SF and Monteray) area CypherPunks are thinking of takeing a bus to Usenix, if you don't live near the Bays you might want to ingore this message.] Ok a bus will cost about $2500 round trip (keeping the bus in the parking lot for the three or four days of Usenix). If we get 20 people to ride the bus the cost per person is about $125, if we get 30 folks the cost per person is about $83, both of these are ROUND trip prices. If you are interested in rideing the Crypto Bus I need a commitment from you as to a price point. If you are willing to ride the bus at say, $115, then send me <hugh(a)toad.com> (and NOT the group!) email saying what your price point is and if we get enough people then we will do a bus. I need as many commitments as possable this week (before the new year) to get a bus reserved, if you don't read this before the new year then respond on monday or tuesday next week. Late commers will be taken on a first come first served basis, if there are enough folks to do a bus in the next few days. Bus will leave SF Bay area and make a day trip into Mexico, and return to SF Bay area. We get to stop and eat where we want! If you are willing to leave early Sunday, Monday, Thursday or Friday so that we can do a long streach of Mexico coast or something please include that in your email to me. If you have questions please feal free to contact me. ||ugh Daniel Just a 555 acting as a Bus Driver...

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Random number generators
by gnu＠cygnus.com 12 Jan '93

12 Jan '93

> MONTE CARLO TECHNIQUES, > widely used in computer simulations of physical systems, entail the > wholesale generation of random numbers. A new study by scientists at > the University of Georgia (Alan Ferrenberg, 404-542-8460) shows that > even the most advanced random-number generators are biased under > certain circumstances (A.M. Ferrenberg et al., 7 Dec. Physical Review > Letters). Using one state-of-the-art program, the Marsaglia-Zeman > random-number generator, Ferrenberg discovered that a simulated > performance of the two-dimensional Ising model (which models the > behavior of a plane of neighboring spins) did not agree with the > results when calculated exactly by mathematical methods. He traced the > discrepancy to the random- number generator. Other generators tried > had differing faults. > (Science News, 19 & 26 Dec.) Can someone get the paper(s) and/or talk to the researcher? Does he have any programs he can throw into the pot for generating or testing random numbers? John

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Re: Politics of Rmailers
by pmetzger＠shearson.com 12 Jan '93

12 Jan '93

> From: Crys Rides <crys(a)eith.biostr.washington.edu> > > >>>>> On Sat, 9 Jan 93 23:32:18 PST, tribble(a)xanadu.com (E. Dean Tribble) said: > > E.> Date: Sat, 9 Jan 93 17:52:01 -0800 > E.> From: uunet!netcom.com!norm (Norman Hardy) > > E.> I can imagine a system administrator choosing to require that > E.> all mail originating from his machine include a signature that > E.> correctly identifies the local name of the sender. > > E.> I can imagine it, but none exist. This is mostly because the From: > ^^^^^^^^^^^ > E.> field is supplied by the mailer and satisfies that requirement, > E.> whereas requiring things in teh body of the mail message goes against > E.> the grain of how the systems are used. > *Bzzzzt* Wrong answer, thank you for playing. The public access bbs > system running out of Chapel Hill, automatically appends the same signature > to all outgoing messages, and other sites are considering the same measures. Mr Rides; Your rudeness is exceeded only by your apparent incapacity to read. As has been stated, quite clearly, no one is doubting that such systems exist. The "none exist" in the last paragraph refers to REASONS FOR THIS PRACTICE, not to the number of sites practicing it. As was said, the "From:" field satisfies the stated requirement without the need for autosignatures. The notion of an automatic footer when automatic headers exist already that satisfy the identification requirement is without merit. Perry

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share room at RSA conference Thursday?
by phr＠napa.Telebit.COM 12 Jan '93

12 Jan '93

Does anyone have crash space, or need some, at the Sofitel hotel on Thursday night? (I'm not sure if it's all booked up or what the room rates are). I live fairly close to Redwood City but figure that staying at the conference hotel is the only way I'll have any chance of getting up early enough for the 9:00 A.M. session on Friday. I might also be interested in splitting up a room on Wednesday night but the interesting sessions on Thurs. don't start til 10:45 a.m. which is not quite as bad... Please reply by direct email, as I'm not on the list any more. Thanks. Paul

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