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The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:20:17 ADT
Bill Frantz (frantz@netcom.com)
Sat, 11 Jul 1998 23:14:54 -0800
At 7:15 PM -0800 7/11/98, Mike Rosing asks:
>Let's first define entropy. According to my reference (Reif,
>Fundamentals of Satistical and Thermal Physics, McGraw-Hill 1965)
>If P is the number of states accessable to a system, then the entropy S
>is given by S = k ln(P) where k is a constant. Entropy is a measure of
>the number of states accessable to a system. Shannon tosses in a minus
>sign, but is measuring the same thing, the total number of chacters is
>the number of accesible states for a communications system.
It think my much more intuitive view is similar to Shannon's. If I have
160 bits of entropy in my system, then the probability of guessing its
current state is 1 in 2**160. That is using only external information
about its state.
In the case of a random number generator, we certainly hope that the
information used to seed it is not included in the accessible external
state. Furthermore, the outputs of the generator should not reveal the
internal state.
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The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:20:17 ADT