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Brute Force attack Question
by ichudov＠galaxy.galstar.com 17 Dec '03

17 Dec '03

Hello, I've been thinking about brute force attacks, and there is something that I do not understand. Maybe someone could explain me where I am wrong. Suppose Alice sends letters to BoB, and they always exchange plain text ASCII data. Suppose also that they use DES for encryption. They are afraid that Perry intercepts their messages and tries to brute force their DES key. Perry has 100,000 computers (and 20,000 couriers alone:) and his brute force attacks are as follows: he tries all keys in succession, looks at the decrypted texts, and *if* the decrypted text looks like a potential message (has only ASCII characters for example) he looks at that key closer as it is likely that he has found the right key. What is Alice and Bob decide to obscure their letters and add random NON-ASCII characters at random places? They may agree to just ignore all non-ASCII characters, so these characters would never change the meaning of their letters. If they do that, Perry does not have any easy way to tell whether he really recovered the right plaintext or not, because even correct key would still produce a lot of non-ASCII characters. If percentage of ASCII characters in all 256 byte space is 40%, Alice and Bob may agree to put in junk characters to make up exactly 60% of the message. This way messages will look like random character data. Is there any good method for attackers to circumvent this obscurity? What is the general method to make a judgment whether the recovered text really is a plain text if Alice and Bob noisify their letters? I can think of this: we sift through all recovered plaintexts and remove all non-ASCII bytes, and then do some simple testing to see whether the remaining ASCII data resembles normal English texts. This kind of testing seems to be quite expensive though, compared to just testing for ASCII vs. non-ascii bytes. Anything else I am missig? Thanks. - Igor.

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Exporting cryptosystems in pieces: Re: Question [NOISE, mostly]
by Bill Stewart 17 Dec '03

17 Dec '03

Cc: vice.president(a)whitehouse.gov, The cypherpunks list has been discussing ITAR again. :-) >> If it is illegal (by our governments standards...) to export programs >>like PGP, etc., and you can send the whole source code in a message >>because that is also considered illegal, then could you send the code, >>broken up into many pieces, and send THAT in Email, would that be >>illegal? Exporting components of military hardware, including cryptosystems, is also specifically banned by ITAR. How big a piece is enough to get you prosecuted is a question for the nastiest of the N prosecutors out there, and whether you can be convicted is a question for the best of the 12 jurors you'll have.... Vince Cate's arms exporter page lets you export a highly-useful fully working cryptosystem in three lines with one mouse click (developed by Adam Back and an international cast of dozens.) Adam Back's export-three-lines-of-PGP-at-once is a more blatant test of this; go see his web pages. Here's my two bits worth - the following bits are components of PGP, Netscape 3.0b5, and also of RSAREF. 0 1 # Thanks; Bill # Bill Stewart +1-415-442-2215 stewarts(a)ix.netcom.com # http://www.idiom.com/~wcs # Confuse Authority!

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Pro-Crypto Fireworks
by jya＠pipeline.com 17 Dec '03

17 Dec '03

Fireworks expected at Thursday encryption hearing Washington, July 24 (Reuter) -- After sailing through two quiet subcommittee hearings, a bill to relax restrictions on computer encoding faces a much choppier ride before the full Senate Commerce Committee on Thursday. The committee will hear from some of the Clinton administration's big guns on crime and national security, including FBI Director Louis Freeh and William Crowell, deputy director of the National Security Agency. [Snip] Netscape's James Barksdale, who entranced senators at a June 12 subcommittee hearing, will return Thursday to again make the case for relaxing export restrictions. [Snip] Others expected to testify Thursday include William Reinsch, undersecretary for the Bureau of Export Administration at the Commerce Department; Tandem Computers Inc. President Roel Pieper; and Grover Norquist, president of Americans for Tax Reform. The hearing will be broadcast live over the Internet, starting at about 9:15 a.m. EDT using Progressive Network's Real Audio software. The technique was first used at a June 26 subcommittee hearing on the encryption bill. Computer users anywhere in the world with sound capability can tune in at http://www.hotwired.com/wiredside. -----

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Keyserver at jpunix.com is retiring
by John A. Perry 17 Dec '03

17 Dec '03

-----BEGIN PGP SIGNED MESSAGE----- The PGP public keyserver at jpunix.com has developed a stability problem over the past week or two that I can't seem to account for. The keyserver stops in the middle of a run and leaves the lock file so all incoming key requests get backed up until I notice it and manually fix it. Having to continually monitor the keyserver has become burdensome and is not doing anyone any good. I've always been happy to provide the keyserver as a public service to the PGP users community but, the keyserver is not getting any better no matter what I do to try and fix it. There are no errors generated and no log entries to point me to what the problem is. With this in mind, I have decided to retire the keyserver at jpunix.com effective 07/27/96 sometime in the AM Central Standard Time. If you have any applications that point to this server, I would ask that you point your application to one of the other servers or make some arrangement to use a different server. It's been an honor and a pleasure to provide this service and I apologize in advance for any inconvenience this may cause. John Perry - perry(a)alpha.jpunix.com - PGP-encrypted e-mail welcome! WWW - http://www.jpunix.com PGP 2.62 key for perry(a)jpunix.com is on the keyservers. -----BEGIN PGP SIGNATURE----- Version: 2.6.2 iQCVAwUBMfacNFOTpEThrthvAQGl0AQAjcBWAe4beWMCZ6yyeoxkgPqjm3hyVmgb 7DeX8/MQ8tpOG+pMzalslBfWRtOaOk9mU/q2N82gEIq6/QcEvY8yUF105+87k6h3 U7mjBnbSjIAGOHBBARo2kzzmfxqVDCoo9SW+idm94HBNeRsIeFFGndII2YHivyP7 milYetDY0b8= =OkkS -----END PGP SIGNATURE-----

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Keyserver at jpunix.com is retiring
by John Perry 17 Dec '03

17 Dec '03

-----BEGIN PGP SIGNED MESSAGE----- The PGP public keyserver at jpunix.com has developed a stability problem over the past week or two that I can't seem to account for. The keyserver stops in the middle of a run and leaves the lock file so all incoming key requests get backed up until I notice it and manually fix it. Having to continually monitor the keyserver has become burdensome and is not doing anyone any good. I've always been happy to provide the keyserver as a public service to the PGP users community but, the keyserver is not getting any better no matter what I do to try and fix it. There are no errors generated and no log entries to point me to what the problem is. With this in mind, I have decided to retire the keyserver at jpunix.com effective 07/27/96 sometime in the AM Central Standard Time. If you have any applications that point to this server, I would ask that you point your application to one of the other servers or make some arrangement to use a different server. It's been an honor and a pleasure to provide this service and I apologize in advance for any inconvenience this may cause. John Perry - perry(a)alpha.jpunix.com - PGP-encrypted e-mail welcome! WWW - http://www.jpunix.com PGP 2.62 key for perry(a)jpunix.com is on the keyservers. -----BEGIN PGP SIGNATURE----- Version: 2.6.2 iQCVAwUBMfacNFOTpEThrthvAQGl0AQAjcBWAe4beWMCZ6yyeoxkgPqjm3hyVmgb 7DeX8/MQ8tpOG+pMzalslBfWRtOaOk9mU/q2N82gEIq6/QcEvY8yUF105+87k6h3 U7mjBnbSjIAGOHBBARo2kzzmfxqVDCoo9SW+idm94HBNeRsIeFFGndII2YHivyP7 milYetDY0b8= =OkkS -----END PGP SIGNATURE-----

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Re: Netscape
by jim bell 17 Dec '03

17 Dec '03

At 07:00 PM 7/23/96 +0000, The Deviant wrote: >On Mon, 22 Jul 1996, Tom Weinstein wrote: >> Also, notice the simple verification system MIT was allowed to use, and >> the complex one we're required to use. >> > >I'm curious, exactly whop is it that _required_ you to use that system.? Excellent point. There's a difference (or, at least, there had BETTER BE a difference!) between following the laws and "doing everything the government wants, exactly the way it wants." It would be interesting to see the specific explanation which was given Netscape as to why they were required (if, indeed, they were required...) to use a specific system. It seems to me that a far more productive stance by Netscape would have been to say to the State Department, "We're going to put this software on the 'net. We're happy to put in any precautions which are SPECIFICALLY required under law and/or ITAR. However, we insist that you document the fact that they are required, with full and complete legal explanations for your assertions. Moreover, we insist that you explain why this position is consistent with MIT's posting of PGP." At the very least, this would have set the government's position WRT ITAR in stone, Part of the reason the governemnt has gotten so much 'mileage' out of ITAR is the fact that they morph it to do whatever they want, whenever they want. The best way to fight this is to tie down their position. Jim Bell jimbell(a)pacifier.com

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FW: Distributed DES crack
by geeman＠best.com 17 Dec '03

17 Dec '03

---------- From: Remo Pini[SMTP:rp@rpini.com] Sent: Wednesday, July 24, 1996 7:34 AM To: cypherpunks(a)toad.com Subject: Re: Distributed DES crack -----BEGIN PGP SIGNED MESSAGE----- To: cypherpunks(a)toad.com Date: Wed Jul 24 16:31:44 1996 Has anyone thought about TI or Motorolas DSP-Eval-Boards (at 99$ a piece at 40 MHz with optimized assembler they might easily outrun a PPro200) Don't look at me that way, I know only little about DSP-Programming. >>> DSP's are optimized for add/multiply ... and you get their memory-access pipelining; but I am not too sure how they'd do on a DES algo. I wouldn't get too excited.

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Re: DES-Busting Screen Savers?
by Bill Stewart 17 Dec '03

17 Dec '03

Tim and others have discussed the effectiveness of random search vs. centralized servers, problems of cheating, scaling, etc. My take is that, if you can ignore scaling, the best approach is probably to have a central server that doles out keyspace and wraps around when it reaches 100%, and doesn't worry too much about collecting results - even if there are cheaters, machine failures, etc., and people don't finish their keyspace, it'll be more likely to cover the whole space than randoms. (Make it a web page, and use cut&paste to transfer to the search programs so they don't need to be network-equipped.) To support scaling, make it easy for people to run subset servers; grab a chunk of keyspace from the main server and dole it out to people who ask you for it. If you want to get fancy, hack a DNS server to allow people to register their machines as NNN.descrack.org, 0<=NNN<1000, so that people can find subsets without having to ask the main server. >>> a brute force "screen saver" for >-- By the time the total amount of computons expended has equalled the >amount that would have been expended in a "no duplications" allocated >search, the Poisson probability distribution says that 1/e = 36.8% of the >keyspace will not have been searched; the rest of the probabilty lies in >keyspace searched once, twice, three times, etc. # Thanks; Bill # Bill Stewart +1-415-442-2215 stewarts(a)ix.netcom.com # http://www.idiom.com/~wcs # Confuse Authority!

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Re: Brute-forcing DES
by Steve Reid 17 Dec '03

17 Dec '03

> Specialized DES-cracker chips have of course been considered. Diffie and > Hellman's nearly 20-year-old paper on cracking DES considered this. > Wiener's calculation of a few years ago did more that this: he also > architected a basic system. And the "how many bits is enough?" (sorry I > don't have the official name on the tip of my tongue) panel considered such > designs last year. Yep, I'm familiar with the issue. Bottom line is, it'll take thousands of times the CPU power of the RC4-40 crack. Probably not 2^16 times more; I think RC4 has a longer initialization. > But actually building a DES cracker entails a level of commitment very > difficult to achieve in an informal, volunteer effort. Not exactly > something that 10 or 20 people can work on usefully. > The advantage of the cracks done last year, the French and Australian > cracks, and the MIT cracks, were that the "entry costs" for joining the > project were low. I'm not talking about one individual or organization building one big DES cracker. I'm thinking that DES chips _could_ be used to supliment the PCs in a distributed crack. People with PCs would feed keyspace through their PCs and people with DES chips could feed keyspace through their DES chips. DES chips just happen to have a _lot_ more cracking power than PCs, so they could make a big difference. Adding one DES chip would be like adding hundreds of PCs to the effort. PCs will probably still be the main factor simply because they're ubiquitous. Even with a bunch of DES chips and a massive legion of PCs, this is going to take a long time. Perhaps we should be looking at the thousands of computers and many months, more like the RSA-129 crack than the RC4-40 crack. >From "The Magic Words Are Squeamish Ossifrage": > We believe that we could acquire 100 thousand machines without > superhuman or unethical efforts. If Lenstra et al know what they're talking about, then WE CAN DO THIS!!! ===================================================================== | Steve Reid - SysAdmin & Pres, EDM Web (http://www.edmweb.com/) | | Email: steve(a)edmweb.com Home Page: http://www.edmweb.com/steve/ | | PGP (2048/9F317269) Fingerprint: 11C89D1CD67287E68C09EC52443F8830 | | -- Disclaimer: JMHO, YMMV, TANSTAAFL, IANAL. -- | ===================================================================:)

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Re: DES-Busting Screen Savers?
by Alan Olsen 17 Dec '03

17 Dec '03

At 05:01 AM 7/25/96 +0000, The Deviant wrote: >> To support scaling, make it easy for people to run subset servers; >> grab a chunk of keyspace from the main server and dole it out >> to people who ask you for it. If you want to get fancy, >> hack a DNS server to allow people to register their machines >> as NNN.descrack.org, 0<=NNN<1000, so that people can find >> subsets without having to ask the main server. >> > >Or hack it to use a 56 bit IP netmask-ish thing, and keep track of keys >that way (i'm not endorsing this idea, just pointing it out) I can see some problems doing this sort of allocation for those of us on dial up providers. When the IP address changes from log in to log in recording the IP address is not much help. You could always hand them a digital signature with the key space signed by the server... --- Alan Olsen -- alano(a)teleport.com -- Contract Web Design & Instruction `finger -l alano(a)teleport.com` for PGP 2.6.2 key http://www.teleport.com/~alano/ "We had to destroy the Internet in order to save it." - Sen. Exon "Microsoft -- Nothing but NT promises."

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