Kernel security: beyond bug fixing [LWN.net]

Kernel security: beyond bug fixing

Posted Nov 3, 2015 5:24 UTC (Tue) by JdGordy (subscriber, #70103)
In reply to: Kernel security: beyond bug fixing by cladisch
Parent article: Kernel security: beyond bug fixing

"A very common error is trying to use a von Neumann extractor to remove correlations (this extractor is guaranteed to work only on data that has no correlations to begin with)."

pardon?!

to post comments

von Neumann extractor is not useful

Posted Nov 3, 2015 7:42 UTC (Tue) by cladisch (✭ supporter ✭, #50193) [Link] (2 responses)

A von Neumann extractor requires that the pairs "01" and "10" are equally likely in its input. This is true for a Bernoulli sequence (which, in toy examples, can be generated with a biased coin), but this has no relation with most random data occuring in the real world.

von Neumann extractor is not useful

Posted Nov 16, 2015 4:10 UTC (Mon) by kevinm (guest, #69913) [Link] (1 responses)

How exactly do you get two consecutive 01 transitions without an intervening 10 transition?

von Neumann extractor is not useful

Posted Nov 16, 2015 5:55 UTC (Mon) by cladisch (✭ supporter ✭, #50193) [Link]

0101
(You cannot use the same bit for two decisions; that would break the output, too.)