Re: Entropy and Equivalent Key Lengths?

From: Allen Pulsifer (amicrypt_at_amishare.com)
Date: 08/13/04 

Date: Fri, 13 Aug 2004 11:17:40 -0400

> if you pick a password of lengh n from a randomly chosen fragment
> of text, then a brute force guessing attack would require 2^(1.3*n) trials
> on average.

I believe it would take 2^(1.3*n - 1), on the average. For example, a
128 bit key has 128 bits of entropy and can be brute forced with an
average of (2^128)/2 = 2^(128-1) tries. After 2^128 tries, you would be
guaranteed to find the key.

Allen

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