Re: [Dev-C++] true random numbers.

> ...
> Don't forget that it is very easy to check 2^32 seed values to find a
> suitable start seed. By knowing within a reasonable time span when the
> random numbers are generated, few random steps need to be tested with few
> stepped times to continue to follow this "random" chain.

Yes.. I agree with you. Since time() doesn't generate true random
numbers, with this EASY approach, better results are achieved... do
you agree with me?


> ...
> By constantly reseed the rand() function, you may also create local
> sequence loops, where the current time() call will result in a seed value
> already used before.

Yes, of course this can happen.... but this introduces a noise in the
resulting sequence.


> ...
> In short, the concept doesn't hold under cryptographic analysis.

Obviously... it is like trying to encrypt a java applet.... it is
impossible, but with all the known techniques, you can make the attack
more difficult, only for those attacks that know how to do it....

With this easy approach, you can add a real noise to the resulting
sequence that makes the analysis more difficult... or isn't it??

> If you produce huge number of random numbers, the sequence generated with
> the same time will be long - easy to catch. If you produce your numbers
> within a very long time interval, the time steps will affect more but then
> the numbers are so few that is still trivial to follow the sequence.

And if it is small set of random numbers, with the proposed function,
reseeding the sequence, and the interval between successive numbers is
not trivial....
do you think that is harder or easier to perform the analysis? 

and if it is used only for choose a random color for my background ?

I know what you are comment... and all it is true... the true random
numbers are difficult to obtain...  And, like the topic was "true
random numbers", I have to agree with that, because I think in the
same way .

But, a good approach for easy applications can be the proposed one in
the first post or in the second one....

In all cryptographic books it is used to appear a chapter about this ...

Bye!


-- 
Aitor Moreno
   ait...@gm...