[lug] Question about /dev/random

[John Hernandez]

Paul E Condon wrote:
> I am doing some MonteCarlo simulation studies for which I use lots of
> pseudo-random integers. I use a /dev/random to provide a seed for the
> generator and display on the console some information about the workings
> of /dev/random. This info puzzles me. 
> 
> During initialization, my program reads and displays contents of 
> /proc/sys/kernel/random/entropy_avail
> Typically this is 4096, the size of the random pool buffer.
> My program then reads 8 bytes (64 bits) from /dev/random and then
> reads .../entropy_avail again. On this second read it finds 3136. 
> Reading 64 bits seems to have decreased the pool by 960 bits. Why?
> 

This old thread may provide some clues:

http://www.uwsg.iu.edu/hypermail/linux/kernel/0110.0/0227.html

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