MetaFilter posts tagged with math and numbers

Beware of Oddity

Potomac Avenue — Thu, 07 May 2009 08:00:50 -0800

Happy Odd Day! Join the facebook group, win 575 dollars! Previously

15 bits of crypto should be enough for anybody

finite — Fri, 16 May 2008 22:01:42 -0800

On May 13, security advisories published by Debian and Ubuntu revealed that, for over a year, their OpenSSL libraries have had a major flaw in their CSPRNG, which is used by key generation functions in many widely-used applications, which caused the "random" numbers produced to be extremely predictable. [lolcat summary] How bad is it? It's pretty bad. Understand that these keys are used not only for encryption, but also for authentication. The keyspace has been reduced to a mere 32,768 possibilities, and you can already download them all, along with tools to use them. Worse still, in the days before the issue became publicly known, there was a noticeable spike in the number of brute-force attacks on SSH servers, indicating that there has already been significant exploitation of this vulnerability. Partial timeline of events: In May 2006, a bug led to a question which led to the fateful patch being applied to md_rand.c (in Debian's "unstable" development branch). In April 2007, Debian 4.0 "etch" and Ubuntu 7.04 were both released, which was the beginning of the inclusion of the buggy version of OpenSSL in officially-released distributions. The bug remained unfixed through the releases of Ubuntu 7.10 and 8.04. On May 7, 2008, the patch to fix the problem was committed to Debian's source repository, and on May 13 the issue was officially disclosed and updated packages were made available to users. (The patch's availability days before public disclosure of the bug appears to be a violation of Debian's policy.) Here are some responses from Debian blogs, and two from an OpenSSL developer.

3 is an odd prime, 5 is an odd prime, 7 is an odd prime, 9 is a very odd prime...

Wolfdog — Tue, 10 Jul 2007 06:34:53 -0800

The Prime Game is not really much of a game, but it is a neat & little-known fact about the decimal representation of prime numbers.

Operation Kaprekar

fatllama — Sat, 13 Jan 2007 22:19:42 -0800

Mysterious number 6174. An excellent recreational math article.

Significant numbers

scarabic — Fri, 11 Nov 2005 14:09:41 -0800

Significance of numbers. Not to be confused with the concept of "significant figures," this page lists the significance of numbers 0 through 1000. See! "2 is the only even prime." Hear! "24 is the largest number divisible by all numbers less than its square root." Thrill! "3367 is the smallest number which can be written as the difference of 2 cubes in 3 ways." Whoa!

Number Spirals

jjray — Thu, 15 Apr 2004 09:40:12 -0800

Number Spirals: Coincidences of order. "In mathematics you don't understand things. You just get used to them."

Oh, it's nothing...

moonbird — Mon, 29 Sep 2003 22:19:04 -0800

This post is about nothing. Zip. Zero. Zilch. Nada.

bicyclingfool — Mon, 30 Apr 2001 22:37:54 -0800

LavaRand ...harnessing the power of Lava Lite® lamps to generate truly random numbers....

That's a bold statement, but who am I to doubt the power of the lava lamp. The mathematical purist may disagree with the "truely random" part, but this geek speak convinced me that LavaRand can handle all my random number needs.

Skot — Thu, 15 Mar 2001 12:40:07 -0800

Mathematician Bums Out Entire Scientific Community His "Omega" number--infinite and incalculable--guts hopes for pure mathematics, physicists' hopes for a Theory of Everything, and is just in general kind of bafflingly cool. Builds on the whole Godel/Turing foundation of hopelessness!