# why we call it entropy - Openssl

This is a discussion on why we call it entropy - Openssl ; Von Neumann counseled Shannon to call it entropy because "no one really knows what entropy is". ;-) I wanted to say that it's inherently problematic to use things like the "randomness" in the interarrival time of events like interrupts, etc. ...

# Thread: why we call it entropy

1. ## why we call it entropy

Von Neumann counseled Shannon to call it entropy because "no one
really knows what entropy is". ;-)

I wanted to say that it's inherently problematic to use things like the
"randomness" in the interarrival time of events like interrupts, etc.
to "gather" "entropy" -- Ted has touched on this with his comment on
solid state disk drives, etc.

A bit stream may have 1 bit of entropy per bit of message (i.e. an
entropy of 1), and therefore be incompressible -- perhaps what Schwartz
thinks he means when he says "truly random" -- and be entirely predictable.

We want nicely-distributed "random" numbers without apparent bias,
with an apparent entropy of one, so that 10 bits of key material
is really 10 bits of key; what makes such numbers cryptographically
useful is that no amount of collected material enables us to
predict bits anywhere else in the stream (past or future, if viewed
temporally).

I have given Herr Schwartz enough of my grossmutterlich Freundlichkeit
for one day. Ppppt.

- M

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2. ## Re: why we call it entropy

Michael Sierchio wrote:

> A bit stream may have 1 bit of entropy per bit of message (i.e. an
> entropy of 1), and therefore be incompressible -- perhaps what Schwartz
> thinks he means when he says "truly random" -- and be entirely predictable.

In case this isn't obvious, apply Von Neumann's corrector to the fractional
component of the binary representation of a transcendental number.

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