07-03-2011
Methods for Random Number Tracking
what types of methods and algorithms are used to track random number generators? I'm working on computer security, and I want to know all the different ways to track random number generators so I know what to counter
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#!/bin/bash
seed1=$RANDOM
seed2=$RANDOM
seed3=$RANDOM
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I saw this formula to generate random number between two specified values in shell script.the following.
$(((RANDOM%(max-min+divisibleBy))/divisibleBy*divisibleBy+min))
Give a example in book.
Generate random number between 6 and 30.like this.
$(((RANDOM%30/3+1)*3))
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928-377-899
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997-997-209
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LEARN ABOUT ULTRIX
setstate
random(3) Library Functions Manual random(3)
Name
random, srandom, initstate, setstate - better random number generator; routines for changing generators
Syntax
long random()
void srandom(seed)
int seed;
char *initstate(seed, state, n)
unsigned seed;
char *state;
int n;
char *setstate(state)
char *state;
Description
The subroutine uses a non-linear additive feedback random number generator employing a default table of size 31 long integers to return
successive pseudo-random numbers in the range from 0 to (2**31)-1. The period of this random number generator is very large, approximately
16*((2**31)-1).
The subroutines have (almost) the same calling sequence and initialization properties as The difference is that rand(3) produces a much
less random sequence - in fact, the low dozen bits generated by rand go through a cyclic pattern. All the bits generated by are usable.
For example, "random()&01" will produce a random binary value.
Unlike does not return the old seed; the reason for this is that the amount of state information used is much more than a single word.
(Two other routines are provided to deal with restarting/changing random number generators.) Like however, will by default produce a
sequence of numbers that can be duplicated by calling with 1 as the seed.
The routine allows a state array, passed in as an argument, to be initialized for future use. The size of the state array (in bytes) is
used by to decide how sophisticated a random number generator it should use - the more state, the better the random numbers will be. (Cur-
rent "optimal" values for the amount of state information are 8, 32, 64, 128, and 256 bytes; other amounts will be rounded down to the
nearest known amount. Using less than 8 bytes will cause an error). The seed for the initialization (which specifies a starting point for
the random number sequence, and provides for restarting at the same point) is also an argument. returns a pointer to the previous state
information array.
Once a state has been initialized, the routine provides for rapid switching between states. The subroutine returns a pointer to the previ-
ous state array; its argument state array is used for further random number generation until the next call to or
Once a state array has been initialized, it may be restarted at a different point either by calling (with the desired seed, the state
array, and its size) or by calling both (with the state array) and (with the desired seed). The advantage of calling both and is that the
size of the state array does not have to be remembered after it is initialized.
With 256 bytes of state information, the period of the random number generator is greater than 269, which should be sufficient for most
purposes.
Diagnostics
If is called with less than 8 bytes of state information, or if detects that the state information has been garbled, error messages are
printed on the standard error output.
See Also
rand(3)
random(3)