Re: /dev/random -- can I enlarge the `randomness stock'?

From: H. Peter Anvin (hpa@zytor.com)
Date: Thu May 25 2000 - 20:22:37 EDT

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    Followup to: <Pine.LNX.4.21.0005260055450.13990-100000@server.serve.me.nl>
    By author: Igmar Palsenberg <maillist@chello.nl>
    In newsgroup: linux.dev.kernel
    >
    > > What if you simply tuned a cheap FM receiver to just static and fed
    > > that into a soundcard. Then reading from /dev/dsp or something would
    > > return pretty good random data, right ?
    >
    > Nope... Unless the receiver recieves a resonable amount of random
    > interference, the data isn't considered random enough.
    >

    Thermal noise is probably your most easily available source of
    randomness. The hard part is estimating the amount of entropy
    derivable, unfortunately; electrical interference can cause the
    entropy to be less than what you would expect. The /dev/random mixing
    function takes care of removing the predictable stuff, but you still
    need to get a value (conservative is fine) for the amount of entropy
    actually available.

             -hpa 

    -- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."

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