Hi ,

The special devices /dev/random and /dev/urandom provide access 
to the Linux kernel's built-in random number generation facility.
Most software functions for generating random numbers, such as the 
rand function in the standard C library, actually generate 
pseudorandom numbers. Although these numbers satisfy some properties 
of random numbers, they are reproducible (for further explanation 
refer TAOCP - Donald Knuth) If you start with the same seed value, 
you ll obtain the same sequence of pseudorandom numbers every time. 
This behavior is inevitable because computers are intrinsically 
deterministic and predictable. It is sometimes possible to break a 
cryptographic algorithm if you can obtain the sequence of random 
numbers that it employs. To obtain better random numbers in computer 
programs requires an external source of randomness.The Linux kernel 
harnesses a particularly good source of randomness: you! By measuring 
the time delay between your input actions, such as keystrokes and 
mouse movements,and the noise from devices, Linux is capable of 
generating an unpredictable stream of high-quality random numbers.

You can access this stream by reading from /dev/random and 
/dev/urandom . 

try 
od -t x1 /dev/random
(Press keys randomly on your keyboard and see the output)

od -t x1 /dev/urandom

you can get more information using :-
man 4 random

hope this helps
:-) ciao

Vinayak Hegde

On Thu, 3 Oct 2002 12:38:25 +0530 Amish Mehta wrote:

> You might want to see
>        perldoc -f srand # PERL random seed documentation.
> 
[snip]

> You should be able to write similar code in C.
> 
> Amish.

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