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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