December 2003 - cypherpunks-legacy

A weakness in PGP signatures, and a suggested solution (long)
by dlv＠bwalk.dm.com 17 Dec '03

17 Dec '03

I've been engaged in a lively debate with a few members of the cypherpunks mailing list about forgeries that are hard to repudiate even if PGP signatures are used. One of the participants suggested that I post a summary to alt.privacy.pgp and sci.crypt, which is just what I'm doing. (My apologies to the mail.cypherpunks readers who already saw much of this once.) I'll illustrate the problem with several scenarios of forgeries. (It's funny that earlier today I was showing a friend how easy it is to post forgeries. She seemed suitably impressed. :) Scenario 1: Bob once sent Carol an e-mail that looked like this: ----------------------------------------------------------------------- From: Bob@boxb To: Carol@boxc Date: 25 Dec 1965 Subject: Carol, we're history Message-ID: <111@boxb> ----BEGIN PGP SIGNED MESSAGE---- I no longer wish to go out with you. Merry Christmas! ----BEGIN PGP SIGNATURE---- Version 2.6.2 12341234... ----END PGP SIGNATURE---- ----------------------------------------------------------------------- Carol can forge an e-mail to Alice that looks like this: ----------------------------------------------------------------------- From: Bob@boxb To: Alice@boxa Date: 25 Dec 1995 Subject: Alice, we're history Message-ID: <222@bobb> ----BEGIN PGP SIGNED MESSAGE---- I no longer wish to go out with you. Merry Christmas! ----BEGIN PGP SIGNATURE---- Version 2.6.2 12341234... ----END PGP SIGNATURE---- ----------------------------------------------------------------------- We assume that it's easy for Carol to forge the RFC 822 headers to make it look like the e-mail came from Bob. That's why many of us use digital signatures. The signed portion of Bob's original e-mail did not state that the message is addressed to Carol (e.g., "Dear Carol"). Alice will probably verify that the signature matches Bob's private key and assume that the e-mail is authentic and has been sent to her by Bob. To repudiate the e-mail, Bob might have to point out that the "Received:" headers differ from his usual e-mails, without relying on PGP. In fact, the presense of his verifiable signature would create more of a presumption of authenticity of Alice's part. Scenario 2: Bob sends the same e-mail as above to Carol. David, a rogue sysadmin, gets a copy of the e-mail, forges the same e-mail as above to Alice. Scenario 3: Bob sends a signed e-mail to Alice. Alice sees it in her newsfeed, forges a Usenet article, makes it look like it came from Bob, and includes the body of Bob's e-mail as the body of the Usenet forgery. Usenet forgeries are easy. Again, if the signed text happens to be suitable, then Bob will have difficulty repudiating the forgery. He won't not be able to use the PGP signature, which will in fact verify. Hopefully, he'll be able to point out that the RFC 1036 Path: header is different from his usual header (which may not be the case). Many Usenet readers would be unconvinced and Bob's reputation would be damaged. Scenario 4: Bob posts a signed Usenet article to alt.sex. Alice forges a usenet article in Bob's name to misc.kids, recycilng the signed body, which would probably be considered inappropriate for misc.kids. Same result as #3. Scenario 5: Bob posts a signed Usenet article to some innocuous newsgroup. Alice reposts the same body in a forgery in Bob's name. The forgery can be cross-posted to numerous "inappropriate" newsgroups ("velveeta"), or multi-posted ("spam"). Certain rogue self-apponited net.cops forge cancels for all copies of Bob's article, including the original. (They are a bigger menace than the forgers :) (As several people know, I have been a victim of some of the above-described kinds of forgeries.) I think the underlying problem is that the way PGP signatures are used by most people, they validate a text, but allow it to be quoted out of context in an e-mail or Usenet forgery. I suggest to the kind folks working on PGP 3 that there should be a standard protocol to include within the signed portion the information on when and for whom this text is written: i.e. the list of e-mail recipients and/or Usenet newsgroups, which could be easily compared with the RFC 822/1036 headers of an e-mail/Usenet article. Perhaps there could be a new option for PGP to look _outside_ the signed block and match the headers with what's inside the block. For example, suppose the signature block says: this text was written by alice(a)zog.org, posted to alt.sex and alt.sex.banal and e-mailed to bob(a)masons.com. Suppose PGP is asked to check the signature in a file that purports to be a e-mail or a Usenet article and has some headers before the signed portion. If there is a list of To: recipients, and it includes someone other than the recipients listed within the signed block; or if there is a Newsgroups: header, and it includes newsgroups not listed within the signed portion; then the input is bogus. For compatibility with the existing software, if the signed block doesn't include this info, then this checking should't be done, of course. After I posted the above suggestion to cypherpunks, one very respected member of that list informed me that "the security multiparts standard (RFC 1848) includes a provision for signing the headers as well as the body of a message. The security multiparts can be used with PGP, and there is even an Internet Draft for it (draft-elkins-pem-pgp-02.txt), but there is not yet consensus for adopting this as a standard on the pgp-mime mailing list." I hope my examples will convince some that present practice of signing pieces of text which can be quoted out of context in a forgery is just not enough. We need to have an easy way to sign the headers without resorting to mine. --- Dr. Dimitri Vulis Brighton Beach Boardwalk BBS, Forest Hills, N.Y.: +1-718-261-2013, 14.4Kbps

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Re: DejaNews and Alta Vista Search Tools, and Privacy Implications
by Bill Stewart 17 Dec '03

17 Dec '03

At 03:28 AM 12/27/95 -0800, tcmay(a)got.net (Timothy C. May) wrote: >Anyway, a point of clarification of a point, lest there be the belief that >_all_ Cypherpunks are opposed to comprehensive Web search tools: ...... ...offshore... ...... >Face it, every single word written by any of us to any Usenet newsgroup, >going back to the beginning of Usenet, and expanding out to many >ostensibly-private mailing lists, will fairly soon be searchable. The Internet not only makes it easier for everybody to get their 15 minutes of fame, it guarantees that anything stupid you've said in public over the last 15 years will be available to the entire world. So deal with it... I'm more bothered by people indexing what I read. What kinds of Cypherpunk technology can we use to affect this? I don't think we need to do too much work on _increasing_ data collection; the commercial markets will figure that one out fast enough, though understanding technical possibilities enough to stay ahead is good. Remailers and nymservers are obvious starts on the information-hiding end, and even the basic non-encrypted cypherpunks remailers are good enough for most applications. The problem is getting them widely deployed. I've seen a couple of web-page-based remailers, and they're probably easy to deploy widely; they're not very secure without SSL, but they're a start, and people on SSL-equipped systems can run them securely. Anon web proxies are more work to deploy, but they're not mysterious, and the main limits to deploying them are economics. Nymservers, however, are still pretty new - technology like anon.penet.fi is generally good enough for most people if you've got an operator you trust, and an economic base that makes it worth running them. But the more secure nymservers are still complex, and probably not something the average hacker can just pop up and run - we probably need to explore them more before it'll be easy to do. While I like getting services provided through community spirit, like most of the remailers, I suspect Tim's right that pay-per-use privacy services are going to evolve, and probably dominate. Among other things, they're in the balance between the couch-potato on-line services and real Internet connections; they're probably more likely to be offered by people who want full-time connectivity, and will be used to offset the slightly higher costs of real service. However, partly due to patent issues, and partly just to convenience, I don't think they all need to use fully-anonymous digicash for every transaction; most of them can get by with service-provider tokens that may be paid for by digicash or by less-anonymous systems. One of the main threats I see to privacy services is the Exon bill - it's pretty obvious that most US service providers will have to limit access to people over 18, in spite of any of the Good Senator's claims otherwise. If the Feds start making examples of people before any serious court cases get decided (or after, if the good guys lose), that probably means that service providers will have to check ID to protect themselves. There may be a market for services that validate that their customers are over 18, but provide anonymity within that. #-- # Thanks; Bill # Bill Stewart, stewarts(a)ix.netcom.com, Pager/Voicemail 1-408-787-1281 # .... Heading back to The Big Phone Company

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Re: AWARD: CHRISTMAS NET SCROOGE - AT&T & NETSCAPE
by nobody＠REPLAY.COM 17 Dec '03

17 Dec '03

-----BEGIN PGP SIGNED MESSAGE----- [ Non-crypto garbage deleted ] The Vince Foster articles were more relevant than this garbage (not to mention the fact they made more sense). P.S. This post is in the public domain. G. E. T. A. F. U. C. K. I. N. G. C. L. U. E. - --- [This message has been signed by an auto-signing service. A valid signature means only that it has been received at the address corresponding to the signature and forwarded.] -----BEGIN PGP SIGNATURE----- Version: 2.6.2 Comment: Gratis auto-signing service iQBFAwUBMOGjoCoZzwIn1bdtAQHRJwF/fATfL+ZmsLlB8wgGdme5QkXExqw8Fa0G MZuaH93wUT5B+VgTQSuWPfqfd+zaUUTo =jf8w -----END PGP SIGNATURE-----

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Did anyone see...
by Marshall Clow 17 Dec '03

17 Dec '03

On C-Span today: 2:06 pm ET/11:06 am PT Secret Codes Used in World War II National Security Agency -- Marshall Marshall Clow Aladdin Systems <mailto:mclow@mailhost2.csusm.edu> "Eternal vigilance is the price of PostScript" -- MacUser Jan 96 DTP and Graphics column

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Re: COMMUNITY CONNEXION ANNOUNCES APACHE-SSL COMMERCE
by Alex de Joode 17 Dec '03

17 Dec '03

: At 01:12 PM 12/26/95 -0800, sameer wrote: : > The Apache-SSL Commerce webserver is the only commercial encrypting : > webserver with source available. Ian Goldberg, graduate student at : > U.C. Berkeley, well-known for his work on SSL security, commented on : > the importance of available source, ftp://ftp.hacktic.nl/pub/replay/pub/apache/ -AJ-

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GEY_ser
by John Young 17 Dec '03

17 Dec '03

12-27-95. W$Jug: A test of superfast cable modems at Boston College prove addictive to speed freak faculty and students downloading junk data in seconds not minutes and hours, thus accelerating mind-rupture. And, an editorial red flags the telecom billions giveaway; nags Republicans to shut the geyser and not-reg the I-Way. GEY_ser

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Crypto specialist wanted
by P.J. Ponder 17 Dec '03

17 Dec '03

CSI's most recent _Computer Security Alert_ has a listing for: Cryptographic specialist for a San Diego based firm. Headhunter's address is: vfalcon(a)onramp.net (I know this is isn't jobs.misc, but traffic having been relatively light, I'm passing this on to others who may be interested in crypto, but aren't on CSI's mailing list. Now back to frequency hopping radios and Anti-Fred)

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German government orders censorship of CompuServe -- a sign of things to come djf
by Dave Farber 17 Dec '03

17 Dec '03

Posted-Date: Wed, 27 Dec 1995 17:47:17 -0500 X-Sender: farber(a)linc.cis.upenn.edu Date: Wed, 27 Dec 1995 17:47:17 -0500 From: Dave Farber <farber(a)central.cis.upenn.edu> Subject: IP: German government orders censorship of CompuServe -- a sign of things to come djf To: FOR IMMEDIATE RELEASE CONTACT: William Giles Russ Robinson CompuServe Incorporated CompuServe Incorporated 614/ 538-4388 614/ 538-4274 COMPUSERVE(R) SUSPENDS ACCESS TO SPECIFIC INTERNET NEWSGROUPS COLUMBUS, Ohio, Dec. 28, 1995 -- During the past week, CompuServe Incorporated temporarily suspended access to more than 200 Internet newsgroups in response to a direct mandate from the prosecutor s office in Germany. Each of the newsgroups that was suspended was specifically identified to CompuServe by the German authorities as illegal under German criminal law. CompuServe did not select any groups or determine the nature of the newsgroups that have been impacted by this action. German government officials, as part of an investigation of illegal material on the Internet, ordered CompuServe to do what was necessary with respect to specified newsgroups in order to comply with German law. German authorities are investigating newsgroups and other Internet content that may contain child pornography, other pornographic material illegal for adults, as well as content that although not illegal for adults is of such an explicit nature that it is illegal for minors. While access has been suspended, CompuServe continues to work with German authorities to resolve this matter. CompuServe cannot alter the content on the Internet in any way and has only suspended access to the disputed newsgroups through CIS. The issues being investigated in Germany, like those being addressed across the industry, need to remain focused on the individuals and groups placing content on the Internet. CompuServe, as an access provider, is not responsible for the origination or nature of content on the Internet over which it has no creative or editorial control. The global market is vital to CompuServe. We currently have 500,000 members in Western Europe and anticipate doubling that number in the next year. As the leading global service, CompuServe must comply with the laws of the many countries in which we operate. However, laws in different countries are often in conflict, and this creates new challenges unique to the emerging online industry. CompuServe is investigating ways in which we can restrict user access to selected newsgroups by geographical location. >

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Only accepting e-mail from known parties
by tallpaul＠pipeline.com 17 Dec '03

17 Dec '03

[Below is the original I failed to post to the group as a whole. Sorry about the temporal confusion that produced.] On Dec 25, 1995 14:53:19, 'Adam Shostack <adam(a)lighthouse.homeport.org>' wrote: > The basic problem is that (personal) spam is a social, not a >technical problem. If someone wants to annoy you via the internet, >they can do so. You can raise the cost of their annoying you, but you >need to be careful not to make it difficult to talk to you. > I agree in many ways. On a personal level, I am far more interested in the *social* are of this form of privacy. It is more a problem of the data-hermit than privacy. And in a society increasingly generating narcissistists, I see the problem getting worse. Negroponte of the MIT Media Lab can sing the praises of the personal e-newspaper with personal filters to cut out everything uninteresting while culling the world new feeds for desired information. I see this feeding into the narcissitism problem. E.G. Imagine two people who "feel" that members of the other gender are "only interested in one thing." Each wakes up in the morning and looks at their personal e-paper. She reads nothing of particularly nasty rapes, serial rapists at large, rapists who have been convicted, and rapists who an uncaring pro-male system has let out to rape again (i.e. been found not guilty). He reads nothing of particularly nasty robberies of men by women, serial robberies by prostitutes, female robbers who have been convicted, and robbers who an uncaring pro-female system has let out to rob again. Both believe that their custom filtered feeds are the *real* events going on in the world and are far more accurate than any non-customized news feed. I hope nobody takes this as a generic attack on the privacy issues that the list is devoted to. I am a great supporter of privacy and pro-privacy tek. But I see myself as a realist on privacy issues, not as a privacy-utopian or a privacy-dystopian. We live in a post-Faustian world. It is divided into two groups of people. First are those who understand the post-Faustian character and devote themselves to getting used to it and even having fun with the new opportunities while understanding that the new world also generates new problems (like furthering data-narcicism). Second are those classic-reactionary forces (from all parts of the political spectrum) who whine about how the post-Faustian world is personally unfair to them and how everybody in the world has a personal obligation to them to move the world back to its pre-Faustian origins. --tallpaul PS to Tim May: I understand your posts on material that is off-topic. I usually agree with your posts. But I see the issues I discussed above as far more on topic (even if highly mediated) than, say, the ongoing discourse on the differences between an Army Captain and a Navy Captain.

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Re: another anonymous poster helping to destroy our rights
by tcmay＠got.net 17 Dec '03

17 Dec '03

At 5:25 PM 12/27/95, Jeff Barber wrote: >Fred Cohen writes: >> >> We just heard from another anonymous poster trying to destroy our rights >> to free speech. How long will the cypherpunks put up with this? > >As Tim May has explained over and over again, "the cypherpunks" do not >exist. Cypherpunks is a mailing list, not a society or club. >"The cypherpunks" as a group can do nothing about what gets posted to >this list except comment on it. Precisely. Some of the many advantages of having no centralized structure/leadership, and no formal rules/policies, are: -- less wrangling over leadership and rules (if you think we wrangle and fight too much, look at organizations that spend *all* of their time choosing leaders, having boardroom fights, setting policies, fighting, electioneering, etc...it makes our easily-filtered flame wars pale by comparison) -- no leaders means no one in a position of leadership to sue for the many "infractions" some of our list members commit (violations of export laws, posting of stolen code, libel, etc., all allegedly, of course) -- no centralized focus, save for the toad.com machine, which could be replaced quickly (or cypherpunks could become "alt.cypherpunks" and then truly have no center, not that I am advocating this, for various reasons). This lack of a point of pressure, a center, means opponents have nothing to jab at...they can't write threatening letters to the "Board of Directors" demanding that certain actions cease, etc. >Finally, it should be noted that the kind of messages you're posting >lately are eerily reminiscent of Detweiler's mental deterioration just >before he went off the deep end. In fact, the line "How long will the >cypherpunks put up with this?" may be an exact quote. Indeed. When I saw this "How long will the Cypherpunks put up with this?" I initially thought it was tongue in cheek. Apparently not. --Tim May Views here are not the views of my Internet Service Provider or Government. ---------:---------:---------:---------:---------:---------:---------:---- Timothy C. May | Crypto Anarchy: encryption, digital money, tcmay(a)got.net 408-728-0152 | anonymous networks, digital pseudonyms, zero Corralitos, CA | knowledge, reputations, information markets, Higher Power: 2^756839 | black markets, collapse of governments. "National borders are just speed bumps on the information superhighway."

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