svn commit: r239569 - head/etc/rc.d

[Xin Li]

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On 09/11/12 15:48, Arthur Mesh wrote:
> On Tue, Sep 11, 2012 at 03:37:09PM -0700, Xin Li wrote:
>> Using gzip is better than not using it though, since 4k worth of 
>> compressed data is better than 4k worth of plain text because of 
>> higher entropy destiny (note that the FreeBSD gzip uses 64K of 
>> input/output buffer for compression by the way so maybe only the
>> first 64K is meaningful if we take only 4k of output).
> 
> Since there is 1:1 correspondence between compressed and
> uncompressed data, entropy should be the same in both. I am not
> sure it's better to use compression than not -- you do end up
> seeding fewer bytes to yarrow, but you spend more CPU cycles
> compressing it...

Well, 1:1 correspondence is when we fed full text to /dev/random,
which we don't, right?  Only the first 4K gets consumed.  So:

Situation 1: we have 45K of plain text, and only first 4k is fed to
/dev/random at about 5 bits of entropy per byte;

Situation 2: we have 45K of plain text, compress to e.g. 25K and only
first 4k is fed to /dev/random at more than 7.6 bits of entropy per byte;

Therefore I think Situation 2 is better than situation 1.

Cheers,
- -- 
Xin LI <delphij at delphij.net>    https://www.delphij.net/
FreeBSD - The Power to Serve!           Live free or die
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