December 1992 - cypherpunks-legacy

Re: Secure Key exchange
by karn＠qualcomm.com 01 Dec '92

01 Dec '92

<phr(a)napa.Telebit.COM> allegedly asks: >> If you meet someone claiming to be John Gilmore, >> how will you know he's not an impostor? Get a copy of last Saturday's New York Times. John's picture appears on page 7. Of course, it's always possible for the NSA to print up a "special edition" of that paper just for you... :-) Phil

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thoughts on digital cash
by Marc Horowitz 01 Dec '92

01 Dec '92

I've thought a bit about digital cash since the thread started here, and I have a bunch of thoughts. I hope I'll be coherent. ** For production use, you want a real, live bank or other entity to issue the "money". Assuming the digital cash is backed by gold, or securities, or something else tangible, you don't want the bank to go away with all your money. Or, if you read in the newspaper "Feds seize First National Bank", you want to know if they've just seized *your* bank, and therefore will be able to watch your deposits and withdrawals. If you don't know who your bank really is, you won't know. ** All of the above applies to your escrow agent (who may be your bank) for similar reasons. Public key systems provide non-repudiability, but knowing provably that a pseudonym just stole money or goods from you doesn't help you get it back. Sure, it tarnishes their reputation, but if they steal a whole lot of money all at once, they won't care. ** Anonymity in banking is a well-known concept. If I transfer money from my numbered swiss bank account to your numbered swiss bank account, nobody knows anything, except who the bank is. And I don't see Switzerland giving up their enviable position in the international banking community willingly. All we need to do is convince a swiss bank to do some digital cash banking. Easier said than done. ** Legality of starting our own anonymous electronic bank: what do the laws say, anyway? As long as I pay taxes on any profit, I can form a sole proprietorship to freely buy and sell purple widgets with very little government interaction. Would it still be legal if I got a whole lot of people to accept purple widgets instead of cash? Would it be legal if we called it "digital purple widgets" instead of "digital cash"? I'd really like to see some sort of digital cash system set up. My feeling is that there would be a stronger demand than most people think for such a thing, even if it weren't anonymous and untraceable and all that. But if it has those features, too, and we do it first, it will get used. And de facto standards are hard to get rid of. Marc

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John Gilmore on CNN
by tcmay＠netcom.com 01 Dec '92

01 Dec '92

Our own John Gilmore's fame in the NSA-tweaking community continues. I just saw John interviewed by CNN for a report on crypto, the recent case involving the Friedman papers, and RSA Data Security's problems getting export licenses for its products. The piece ran on "Headline News," and possibly on the main CNN channel as well (as is typical). John spoke about crypto and the need for private individuals to have secure communications, a woman from CPSR spoke about recent threats to further limits communications privacy, and Jim Bidzos from RSA spoke about licensing for exports. The NSA had no substantive comment. All in all, no surprises for any of us. It was too brief, of course, but seemed fairly done. Reports like this will gradually get the word out. By the way, you should all check out John's excellent articles he wrote in sci.crypt about the declassification of the Friedman papers. If you don't have Usenet access, I'll mail them to the first several people who request them. (I'd just post them here, but John's in Japan and I can't get his permission.) --Tim -- .......................................................................... 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 | PGP Public Key: by arrangement.

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Chaum's DigiCash
by Marc Horowitz 01 Dec '92

01 Dec '92

Does anybody have any contact information for David Chaum or DigiCash? I think it's worthwhile to find out if any of the problems we've been discussing have been previously solved. It's possible that our experiment could increase visibility of digital cash to the point that a real commercial venture could work, in which case he may even be interested in helping us. Email me personally, I'll summarize. Marc

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386des wanted
by S.E. Brown 01 Dec '92

01 Dec '92

Does anyone possess a copy of the des package 386des? I've heard that it is incredibly fast, and would like to look at a copy. I have been unable to find it on any of the regular crypto haunts on the inet. Thanks in advance Shawn

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Re: remailers
by ghsvax!hal＠uunet.UU.NET 01 Dec '92

01 Dec '92

Fen Labalme quotes some messages with concerns about people needing permission from the sysadmins to run remailers. The current remailers, based on Eric Hughes' approach, don't have this problem. I don't even know who the sysadmin is on the system where I run the remailer. They don't know anything about it. Eric's remailers don't require continual processes to be run, root privileges, hacking the mail tables, or anything special. All you need is to be on a Unix system which supports the ".forward" file. This is typically implemented by the mail programs which deliver mail to the user's mail file. The programs check to see if a file called .forward exists in the user's home directory, and if so they treat its contents as either a program to pipe the incoming mail into, or a user name or list of user names to send the mail to. This is the hook by which Eric's remailers operate. The .forward file is set up so that mail is piped to a program which sorts the mail based on its headers, using the mh utility slocal or, in my case, a perl script which provides some of the same functions. Each message is checked like this, and if it doesn't contain any of the special stuff which activates the remailer software, it is simply deposted in the user's mailbox file as usual. Otherwise the remailers run and forward it as requested. With this solution, there's no need for anybody to be aware that you are running a remailer, as long as it's not too much of a load in terms of extra message traffic. Hal 74076.1041(a)compuserve.com

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Why not just do it?
by mark＠coombs.anu.edu.au 01 Dec '92

01 Dec '92

With all the talk of banking regulations etc with regard to messing with the monetary system, why dont we just create a test system where everyone emails in an amount that they are prepared to coughup if they really had to, but at the moment dont (have to). Then we can go ahead with the digital "cash" scenario and not be governed by the banking/security laws of any country because no real money is involved. The object is to get a system going, find flaws, create software and protocols and basically experiment with it. The issue of actual cold hard cash is, to me, a not important. After all it's just numbers. Eric volunteered to do this earlier and, if he still wishes to, I'd be willing to participate in it. Maybe he doesnt have the benefit of a big cushy bank trust account earning him intrest for his work, but I dont think that was a consideration for him anyway. Mark mark(a)coombs.anu.edu.au

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Rumors of your existence
by Joe Thomas 01 Dec '92

01 Dec '92

As a follower of sci.crypt and comp.org.eff.talk, I felt I had to check up on the owners, if any, of this e-mail mailbox that was listed at the end of St. Jude's "Cypherpunk Movement" article in Mondo 2000 Issue 8. How "patently false" are the rumors you can be contacted here? Joe

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Re: Unlabelled PGP messages
by wcs＠anchor.ho.att.com 01 Dec '92

01 Dec '92

Hal Finney points out some problems with unlabelled messages, where the headers don't identify the public key by keyid - remailers include your email address, while newsgroups / broadcasts might have a LOT of articles, such that decrypting them to see if they're for you would be impractically slow. Some techniques that may help: - a remailer-to-newsgroup anonymous poster, which lets you send the remailer articles (presumably with unlabelled keys) to be posted to the alt.whatever group -- should be an easy combination of existing tools. - include an optional non-address label along with the unlabelled message. If you're having an ongoing secret conversation with somebody, you can secretly tell them the label to include, Subject: Unlabelled PGP message label: fnord If you don't see the fnords, you don't have to decrypt them. You don't want to use anything that can be traced to you, and you probably don't want to use labels in a sequence, or use the same label throughout a conversation, but it could help. You could also, if you're only mildly paranoid, use something like a 4-bit checksum of the PGP key or the key length as a label - it's not enough to identify which key it is, but it's enough to cut down on your decryption by a factor of 16. A longer checksum is too revealing - even 8 bits identifies 1/256th of the crypto community, which isn't very anonymous. With all these methods, if you're concerned about traffic analysis, you've still got to download the messages you don't care about to your machine before discarding them. - The Conventional Data Encryption (DEK) packet includes a checksum, which lets you know if you've successfully decrypted it using the RSA key, so you can tell quickly enough whether a message is for you, without decrypting the message itself. The RSA step probably takes most of the time for short messages, but it's still a win. (PGP does lose some security this way, since the Bad Guys can also tell if their exhaustive search of PGP keys has gotten the right one, and now they can go beat up the Key-Certifier to find out who the key really belongs to, but it's a start. If you want heavier anonymity, you have to do without the checksum. There's also an extremely small chance of an incorrect PGP key producing a correct checksum, but it's about 2**-26, and it still gives an incorrect session key.) Bill Stewart, somewhere in New Jersey

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