December 2003 - cypherpunks-legacy

Re: Weak RSA keys?
by cme＠ellisun.sw.stratus.com 17 Dec '03

17 Dec '03

>Date: Thu, 7 Oct 93 14:35:52 -0700 >From: hughes(a)ah.com (Eric Hughes) >Message-Id: <9310072135.AA01702(a)ah.com> >Out of curiosity, does anybody here know how to calculate any >expectations for gcd(p-1,q-1) for, say, 2^n < p < q < 2^(n+1) ? I >don't know enough number theory myself. Eric, I don't think it's number theory you want so much as probability theory. I'm going to look at this to get the answer to the problem as you formulated it, but for values of n large enough (or, for values of 0 greater than (2^{-n}) :-) there's a simple form for that expected value. You can take it as an upper bound for the actual one: [note: I haven't verified this more than once...] E = sum_i sum_m p_i^{-m} where p_i is the i-th prime. - Carl

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E[gcd(p-1,q-1)]
by cme＠ellisun.sw.stratus.com 17 Dec '03

17 Dec '03

I just wrote: > > E = sum_i sum_m p_i^{-m} > >where p_i is the i-th prime. That didn't take into account that p and q were knwn to be odd. So, assuming p and q are randomly chosen odd numbers: E[gcd(p-1,q-1)] < 2.5 + sum_j 1/(p_j - 1) where p_j is the j-th odd prime. It's "<" because this doesn't take into account that there are (relatively small) values of m such that p_i^m > min(p,q). It also doesn't take into account the second order probability effects from depeltion of range. - Carl

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Re: The Bank of the Internet!? (fwd)
by msattler＠netcom.com 17 Dec '03

17 Dec '03

At 16:14 93/10/10 -40962758, Douglas Barnes wrote: >At the moment we are beginning the process of surveying members of local >groups and employers in the high tech field to see if they are interested >in being part of the field of membership of a fully digital Credit Union. >We had our first Austin cypherpunks meeting yestereday, and it's clear that >they will be the core of the new CU. And when you look further... I'm ready! ----------------------------------------------------------------------------- Michael S. Sattler msattler(a)netcom.com +1 (415) 358-3058 Digital Jungle Software Encrypt now; ask me how. (finger for PGP key) All that is required for evil to triumph is for {wo}men of good will to do nothing.

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Breaking DES
by an41418＠anon.penet.fi 17 Dec '03

17 Dec '03

My understanding of how an exhaustive search on the key space can be used to break DES is that for every key, K, D(K,Cipher) is applied until the output matches something legible. Say that some random string, to be thrown out, is added to the beginning of the plain text, and that DES is applied in cbc mode, then how could such an attack work? My point, I don't see how DES can be broken if the initial block is a grabage block, and cipher block chaining is used. Please enlighten me (gently). One other point... is the decision to encrypt - decrypt -encrypt when applying triple des arbitrary? Why not just encrypt with k1 and then encrypt with k2. Isn't the effect the same? Thanks a lot, Wonderer ------------------------------------------------------------------------- To find out more about the anon service, send mail to help(a)anon.penet.fi. Due to the double-blind, any mail replies to this message will be anonymized, and an anonymous id will be allocated automatically. You have been warned. Please report any problems, inappropriate use etc. to admin(a)anon.penet.fi.

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Zimmerman on the Hill....
by Peter Wayner 17 Dec '03

17 Dec '03

What time will Zimmerman be delivering his telegram to the Hill tomorrow? Does anyone know the date and time and location? I would appreciate the information. Thanks, ' Peter Wayner

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Re: RSA Security
by peb＠PROCASE.COM 17 Dec '03

17 Dec '03

> if someone were to discover a efficient method for >factoring, I don't believe that we would know about it for a long time. Yes, but consider that being world famous has its advantages for contracting and lecture fees... If factoring were discovered to cost polynomial time, then it would require an international math hooligan conspiracy to keep it quiet. Paul

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RSA Security
by nobody＠rosebud.ee.uh.edu 17 Dec '03

17 Dec '03

Everyone here, of course, knows that breaking the RSA encryption scheme can be no harder than factoring huge numbers. The present security in RSA rests in the fact that nobody has found an efficient way to do it. At the same time, however, nobody has been able to show that it can't be done. We are simply going on faith and past history. The problem is that if someone were to discover a efficient method for factoring, I don't believe that we would know about it for a long time. For example, if by some stroke of genius, I were to discover an efficient way to factor, you would never hear about it from me! Being the greedy person that I am, I would say to myself: "How can I make a buck from this?". I would probably go to the government or some company (quietly) and say to them: "For X dollars each, I will break RSA keys for you." The beauty is that I would not need to disclose the algorithm for factoring. They could easily check if the results that I gave them were correct!

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Why X/Open in London?
by Duncan Frissell 17 Dec '03

17 Dec '03

I noted that Novell was supposed, today, to assign its rights to Unix to the X/Open consortium based in London. You don't suppose that X/Open was founded in London so that future Unix versions could integrate crypto without bothering with US export laws. <G> Another blow to America's competitiveness. Duncan Frissell --- WinQwk 2.0b#0

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Security through obscurity
by an41418＠anon.penet.fi 17 Dec '03

17 Dec '03

I know that it is pretty much accepted by the security community that security through obscurity is useless. There are countless references to this, and it is a strong argument in favor of publishing algorithms. >From time to time, however, it is healthy to question policies such as these and ask ourselves whether or not this is a good idea. It seems that Denning has changed her mind on this by advocating the secrecy of the skipjack algorithm. All of the known plaintext attacks on algorithms such as DES, that involve exhaustive key search are based on knowledge of the algorithm. Wouldn't keeping the algorithm a secret render such chips, as the one presented in Eurocrypt '93 useless? I agree that analysis is more difficult when you don't know if an intruder has compromised your algorithm, but if it were my data that I wanted kept secret I wouldn't give the cracker a head start by publishing my algorithm. Clipper has proven how difficult it is to reverse engineer an algorithm. Let me just say that I know I have violated an accepted doctrine of computer security, but I think it's okay to question even the most accepted ideas every once in a while. I thought this would be a bit provocative. Wonderer ------------------------------------------------------------------------- To find out more about the anon service, send mail to help(a)anon.penet.fi. Due to the double-blind, any mail replies to this message will be anonymized, and an anonymous id will be allocated automatically. You have been warned. Please report any problems, inappropriate use etc. to admin(a)anon.penet.fi.

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Re: Zimmerman on the Hill....(the details)
by djw＠eff.org 17 Dec '03

17 Dec '03

Phil Zimmermann will be testifying Tuesday October 12th at 1:30 pm: Rayburn Room 2172 House Foreign Affairs Committee Subcommittee on Economic Policy, Trade, and the Environment Also featured will be demos of DES downloaded from foreign ftp sites and a large array of foreign-produced DES-based security packages. [It's always wise to check the room assigned on the day of the hearing.] ................................................................... Daniel J. Weitzner, Senior Staff Counsel <djw(a)eff.org> Electronic Frontier Foundation 1001 G St, NW Suite 950 East Washington, DC 20001 202-347-5400 (v) 202-393-5509 (f)

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