[21555] in cryptography@c2.net mail archive
Re: Entropy Definition (was Re: passphrases with more than 160
daemon@ATHENA.MIT.EDU (Greg Rose)
Thu Mar 23 20:52:09 2006
X-Original-To: cryptography@metzdowd.com
X-Original-To: cryptography@metzdowd.com
In-Reply-To: <44221178.5010406@av8n.com>
Date: Thu, 23 Mar 2006 14:50:01 -0800
To: John Denker <jsd@av8n.com>
From: Greg Rose <ggr@qualcomm.com>
Cc: Aram Perez <aramperez@mac.com>,
Cryptography <cryptography@metzdowd.com>
At 22:09 -0500 2006/03/22, John Denker wrote:
>Aram Perez wrote:
>
>>* Can you add or increase entropy?
>
>Shuffling a deck of cards increases the entropy of the deck.
As a minor nit, shuffling *in an unpredictable manner* adds entropy,
because there is extra randomness being brought into the process. If
I was one of those people who can do a perfect riffle shuffle,
reordering the cards in this entirely predictable manner does not
increase or decrease the existing entropy.
So in one sense, the answer is a simple "no"... nothing you can do to
a passphrase can increase its (that is, the passphrase's) entropy.
You can add randomness from another source, and increase the total
entropy, but I don't think that is relevant to the original question.
Greg.
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