December 2003 - cypherpunks-legacy

Discrete logs 1
by Hal Finney 17 Dec '03

17 Dec '03

"Even adders can multiply using log tables..." PGP is moving to discrete log based cryptography. It will still support RSA, but people will be encouraged to generate discrete log keys. It will use RSA to encrypt to people with RSA keys, and discrete log crypto to encrypt to people with discrete log keys. Many discrete log cryptosystems will be patent free after next year. It may be that they will become more popular over the next few years for that reason. RSA has several more years before its patents expire. Most people are not as familiar with the math behind discrete logs as they are with RSA. The general idea of the difficulty of factoring is pretty easy to understand. It's much easier to multiply two large primes together than to figure out what the primes were just by looking at the result. Discrete logs require a little more explanation. First I am going to write a little bit about the lore of logarithms. I think today a lot of people don't know what they are. When I was a boy, in the 1960's, computers and even calculators were not widely available. Yet engineers in many fields needed to perform calculations. Reaction rates, material strengths, friction, current flow, all such calculations require multiplication and division of numbers with several significant digits. The choices were basically to multiply it out the long way, which was slow, error-prone, and wasteful because it generates twice as many digits as you need; use a slide rule, which usually only gets you two or three digits of accuracy; or to use log tables, which could get you four or five, or sometimes even more, accurate digits. The logarithm of a number is the power that you have to raise some specified base (usually 10 for these purposes) to in order to get that number. The logarithm of 100 base 10 is 2 because 10**2 = 100. The log of 1000 is 3. For numbers not powers of 10, the logarithm has fractional parts. The logarithm of 20 is about 1.3, for example. To multiply two numbers, you find their logs and add them, and then turn the result back into a number. To divide, subtract the logs. So most of the work is just in looking up what the logs are using published tables. Actually we do use logs in a crude form in much of cryptography. Any time you say that the product of two 512 bit numbers is 1024 bits what you mean is that the log base two of the smaller numbers is about 512, and so the log base two of their product is 512+512 or 1024. By the time I was in high school calculators were becoming fairly widespread, but we still learned how to use log tables to do multiplication and division. Whole books were published containing nothing but tables of the logarithms of numbers. You can still find these sometimes in used book stores. There were lots of tricks to using these tables which we had to learn. Logarithms of numbers less than 1 are negative, but the trick was to treat them as the sum of a positive fractional part and a negative integer, so for example the log of .2 was treated as +.3 - 1. This made it easier to look up the values. And there were special sub-tables within the tables to help with interpolating, looking up log values between the entries in the table. Using these you could get more accuracy in your answers. All this was part of the craft of working engineers and scientists of the time. It's hard for people today, raised on throwaway and even virtual calculators, to understand the sense of power that came from using logs for calculations. Until we learned these advanced techniques the only accurate alternatives were the terribly tedious hand methods. Being able to get results by adding up a few numbers from a book was an amazing improvement. The discrete logs used in crypto have very different mathematical properties than regular logarithms, but I thought this bit of history would spark some memories in old-timers and give a new perspective for younger people. Hal

3 2

Key for dbell@maths.tcd.ie (key id 0x20C0C719)
by Derek Bell 17 Dec '03

17 Dec '03

-----BEGIN PGP SIGNED MESSAGE----- In message <199610310150.RAA09499(a)blacklodge.c2.net>, Lou Zirko writes: >Date: Wed Oct 30 20:49:53 1996 >Can you provide the key for key id 0x20C0C719, or a location where it can >be obtained so that your signed messages to cypherpunks can be verified. OK - my key is at http://www.maths.tcd.ie/~dbell/key.asc Apologies for the oversight, Derek -----BEGIN PGP SIGNATURE----- Version: 2.6.3ia Charset: noconv iQCVAgUBMnjte1XdSMogwMcZAQHPTwP/RvZ6psgaexodOyQ7MvzeS58UdhDZymA6 lJJMyc9ndKeL7v+z6nMzSxA+Isnhe1huGFs9A8ICFVXY6zT+uml//352StwClIoc 0qR4N64vHJVz1G7O5uXjyehT+viI08R5f6qdH5tDjJ9Zt7+zLRCDGOVcCp5mgSdO BRkAQuB+u9Y= =uBxL -----END PGP SIGNATURE-----

1 0

Inappropriate postings
by Kimmo Suominen 17 Dec '03

17 Dec '03

Dear Cypherpunks, I apologize for having gatewayed inappropriate messages to this mailing list via my systems. One of our new feeds for centralized mailing list subscribal was leaking in messages from their USENET feed. I've asked them to fix this. I have also taken steps to make sure no such misconfigured systems can cause gatewaying through my system again. Sincerely, Kimmo Suominen Trans-Atlantic Communications

1 0

COR_set
by John Young 17 Dec '03

17 Dec '03

10-31-96. FiTi: "How to crack secret computer codes." Bellcore researchers plan to publish on the Internet this week technical details of a new method of cracking encryption systems used to protect computer data. The approach relies on spotting errors made by computers and applying a mathematical equation to work out secret encryption codes. "This is very sophisticated math. The only people who will understand it are other cryptography experts." ----- http://jya.com/corset.txt (3 kb) COR_set Details of the Bellcore smartcard hack? When, where?

1 0

RE: tcmay in favour of redistribution of wealth?
by Duncan Frissell 17 Dec '03

17 Dec '03

At 02:27 PM 10/31/96 +0000, Hard Media wrote: > >Where Walter Wriston/Third World debt is concerned the events are not >natural, we'r not talking about a flood, which is a "natural" event but the >actions of a man, or if you prefer an organisation. There is nothing "natural" >about these. > >A country in debt to the IMF/World Bank or Citibank must accept >"Stabilisation Policies" : Tim is opposed to the existence of the World Bank and Robert McNamara. No libertarians I know of favor the existence of the World Bank. DCF

1 0

Computer Security Risk Assessment Software?
by Ross Wright 17 Dec '03

17 Dec '03

On or About 31 Oct 96 at 12:19, Dr.Dimitri Vulis KOTM wrote: > which I assume is NOT what you have in mind :-) Do you mean > something that'll take a survey of a company's computer security Boom. Nail, head, one shot!!!! What's on the market now in that area? > and > assess the risk (like Stan) or something more global? The issues are: Information Risk Assessment and Management and also Information Security Assessment. > AFAIK, there's > no tool on the market to help in all aspects of risk management even > for a small outfit, because there are so many sources of risk. There > are many good specialized packages. "Ross Wright" <rwright(a)adnetsol.com> writes: > I am about to do some marketing on a certain company's Risk > Assessment Software. At this time I can't say who that firm is, but > I need information on what other firms are offering this type of > software. I figured someone on this list would know. =-=-=-=-=-=- Ross Wright King Media: Bulk Sales of Software Media and Duplication Services http://www.slip.net/~cdr/kingmedia Voice: 415-206-9906

1 0

Shift Control's new look
by the.news＠shiftcontrol.com 17 Dec '03

17 Dec '03

Shift Control has a new look this week. It's out with the old red, black and white, and in with a distinctly tasteful blue and cream. And the change in colours is just the start. We've listened to the feedback we've had about the site, and made it quicker and easier to access and read. The content, of course, is as good as ever. In Critical Shift, William Leith asks what has happened to our heroes. "We don't want heroes anymore," he writes, "because we think we've failed as a race. We are hungry for stories which tell us about how nasty and greedy and self-destructive we are, because this is what we believe. We don't fall for a nice, smiling man who is nice to people. We wonder what he's hiding." In Write Out of Control, we have three new pieces of writing. There's the next exclusive (and rather shocking) instalment of Toby Litt's novel, 'œ'. We also have the first winner of our White Out of Control competition. Not only can you read it, but you can also write the sequel and win £200. And, in 'Large', Nick Green describes an awesome summer of pills and thrills on the festival scene. "The first event of the summer," he writes, "saw me at my most ineffectual, having been rendered completely useless by what can only be described as 'a lethal drugs cocktail'. I didn't realise that a seemingly harmless combination of acid, speed, Ecstasy and skunk could be quite so debilitating." In Plug n Play we bring you an interior design special - From Habitat to Hell and Back - and Fags-u-like, in which our special panel of cigarette connoisseurs smoke their way through several packs of fags in order to tell you which are the best. We've also changed our weekly diary. Instead of Roland bragging about his hyperactive social life, he now presents you with 10 essential cultural happenings for the week ahead. Gigs, clubs, movies and books - they're all in Roland's diary. Yes, you'd be mad not to visit www.shiftcontrol.com this week. Regards, The Shift Control Team Shift Control is produced by the Guardian New Media Lab, with help from Stella Artois and Boddingtons.

1 0

Re: silly putty
by Adamsc＠io-online.com 17 Dec '03

17 Dec '03

On Wed, 30 Oct 1996 17:19:38 -0800 (PST), sameer wrote: > Would anyone be interested in 50 pounds of silly putty? A >friend of mine would be grateful if I could help him get rid of 50 >pounds of silly putty. It would be $500. You mean that silly putty sells for more than tri-tip? # Chris Adams <adamsc(a)io-online.com> | http://www.io-online.com/adamsc/adamsc.htp # <cadams(a)acucobol.com> | send mail with subject "send PGPKEY" "That's our advantage at Microsoft; we set the standards and we can change them." --- Karen Hargrove, Microsoft (quoted in the Feb 1993 Unix Review editorial)

1 0

Re: German Draft Digital Signature Law
by um＠c2.net 17 Dec '03

17 Dec '03

Some more crypto-related news from Germany: In Germany, online banking is a very popular application of the phone company's online service T-Online. Now Bank 24, a subsidary of Deutsche Bank, is beginning to offer online banking on the Internet (http://www.bank24.de) They use SSL to transfer Java applets that securely encrypts the financial data. Export SSL is secure enough to guarantee that the applets are authentic. So much about exporting crypto hooks... As journalist Detlev Borchers reports, the German tax consultants' association Datev (http://www.datev.de) distributes a software toolkit that allows their clients to transfer confidential data to the consultants via AOL. CompuServe or T-Online. The toolkit uses PGP to encrypt the data. At a press conference, the Datev spokesman was very surprised to learn about political problems with encryption software -- because as he said, the German tax authorities also use PGP (however, in a variant where the patented IDEA algorithm has been replaced). Last, but not least: Addison Wesley Germany has now published a German edition of Applied Cryptography. The book does contain source code. I wonder how they got the "munitions" from the US to the German printer?

1 0

On the Importance of Checking Computations
by John Young 17 Dec '03

17 Dec '03

The Bellcore report, "On the Importance of Checking Computations" on technical details of fault-based cracking reported in today's FT, is available at: http://www.bellcore.com/SMART/index.html Here's an outline: On the Importance of Checking Computations (Extended abstract) Don Boneh, Richard A. DeMillo, and Richard J. Lipton Math and Cryptography Research Group, Bellcore Abstract: We present a theoretical model for breaking various cryptographic schemes by taking advantage of random hardware faults. We show how to attack certain implementations of RSA and Rabin signatures. We also show how various authentication protocols, such as Fiat-Shamir and Schnoor, can be broken using hardware faults. 1. Introduction Transient faults Latent faults Induced faults 2. Chinese remainder based implementations 2.1 The RSA system 2.2 RSA's vulnerability to hardware faults 3. Register faults 4. The Fiat-Shamir identification scheme Theorem 4.1 4.1 A modification of the Fiat-Shamir scheme 5. Attacking Schnoor's identification scheme Theorem 5.1 6. Breaking other implementations of RSA Theorem 6.1 7. Protecting against an attack based on hardware faults 8. Summary References ----- Registration is required for access. Two formats are available: Acrobat PDF (112kb) and Postscript PS (86kb). Before registration, there is a brief "context" at: http://www.bellcore.com/SMART/secwp.html Here's the first two paragraphs: Context for "On the Importance of Checking Computations" "On the Importance of Checking Computations" describes a fault-based method for breaking various cryptographic algorithms and exposes the degree to which computing faults can compromise information security. Once the authors -- Richard DeMillo, Dan Boneh and Richard Lipton -- articulated and proved their conceptual breakthrough, they realized that it might be successful in a wide variety of application scenarios. Fault-based attacks potentially endanger many network security products and systems. The paper summarizes the proof for the basic attack. Proof for fault-based cryptanalysis builds on the premise that an adversary can observe a faulty computation that occurs during cryptographic transactions. The faults that are exploited can occur at various sublevels within the logic level of a computing device -- that is, in the switching circuitry where arithmetic operations are performed or in the register transfer area where temporary values are stored in memory. The likelihood of faults occurring is not discussed in the paper. [Snip balance of Context]

1 0