Re: [WEB SECURITY] Using JavaScript to generate "secure" passwords.

["Stephan Wehner" <stephanwehner@xxxxxxxxx>]

On Jan 31, 2008 9:42 AM, Michael Vance <Michael.Vance@xxxxxxxxxxxxx> wrote:
> I think that Billy's original point is still valid.  If the algorithm that is being used is known or easily guessed (and the SHA family would be the best first guess for long hash values), then the entropy of the hash results is identical to the entropy of the source and is still subject to pattern analysis and replay techniques.  If you only have 1,000,000 possible source values, you still only have only a fixed set of 1,000,000 possible hash values.  Those values may appear to be more random to the human eye because they're longer and cryptographically generated, but all you've done is substitute one set of values for another with a one-to-one relationship.  That would be like saying that a substitution cipher is more secure if you replace each single letter with a three-letter combination.  That may be true, but only trivially so for modern cryptanalytic techniques.

Since the page has a nice indicator of how much entropy has been
collected, I think the problem is more about how that indicator is
moved. So input is : mouse-coordinates over time, output is estimate
of entropy collected. That looks like a different problem to me; it's
not gathering entropy as such, but determining how much entropy has
been gathered.

(Might it be easier to ask the user to pound away at the keyboard and
collect the keystrokes?)

Stephan

> -Michael


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Stephan Wehner

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