Random number generator

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Random number generator

Jagannadha Bhattu
Hi,

I am not sure if this is the correct mailing list to post this query.
I can appreciate anybody who can point me the right one, if this is
not the one.


After reading about random number generators I did some search in
internet and learnt that all the software random number generators
have a period. Even the blum blum shub and RSA have the period and
that the sequence will repeat it self after some time though the time
period is very long. I also read that it is possible to implement a
random number generator with a period of the life time of the
universe. But this also theoretically has a limit. What I want to know
is, is there any algorithm that theoretically has no period.

Thanks
JB
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Re: Random number generator

Bernhard Fröhlich-2
Jagannadha Bhattu wrote:

>Hi,
>
>I am not sure if this is the correct mailing list to post this query.
>I can appreciate anybody who can point me the right one, if this is
>not the one.
>
>
>After reading about random number generators I did some search in
>internet and learnt that all the software random number generators
>have a period. Even the blum blum shub and RSA have the period and
>that the sequence will repeat it self after some time though the time
>period is very long. I also read that it is possible to implement a
>random number generator with a period of the life time of the
>universe. But this also theoretically has a limit. What I want to know
>is, is there any algorithm that theoretically has no period.
>  
>
You won't find such a algorithm which can be implemented on a computer,
since you'd have to work with numbers of infinite size.
If you use numbers with a finite size (which is the custom on current
computers) you can easily (in theory) calculate the possible number of
permutations, you'll find a period for every given sample size. Though
usually you'll have to search for a VERY long time.
Computers indeed are not built for eternity... ;)

>[...]
>  
>
Hope it helps,
Ted
;)

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Re: Random number generator

Mouse-2
In reply to this post by Jagannadha Bhattu
Of course all software RNG have their period! Because they are *P*RNG - PSEUDO random number generators. In other words - good enough for a limited time, and assuming that the adversary cannot get the seed. There can possibly be no software-based true RNG: if it is produced by an ALGORITHM, then it is DETERMINISTIC to begin with! As the same algorithm given the same input, would produce the same output - hardly "random".

RNG must be based on some physical effect, that itself is random. You can COLLECT randomness from various sources, such as zener diode noise, fluctuations of disk seek time, etc. So software can be a PART of an RNG (like the code that accesses and retrieves the data), but never - the source of random data.

----- Original Message -----
From: Jagannadha Bhattu <[hidden email]>
Date: Friday, July 15, 2005 4:47 am
Subject: Random number generator

> Hi,
>
> I am not sure if this is the correct mailing list to post this query.
> I can appreciate anybody who can point me the right one, if this is
> not the one.
>
>
> After reading about random number generators I did some search in
> internet and learnt that all the software random number generators
> have a period. Even the blum blum shub and RSA have the period and
> that the sequence will repeat it self after some time though the time
> period is very long. I also read that it is possible to implement a
> random number generator with a period of the life time of the
> universe. But this also theoretically has a limit. What I want to know
> is, is there any algorithm that theoretically has no period.
>
> Thanks
> JB
> ______________________________________________________________________
> OpenSSL Project                                 http://www.openssl.org
> User Support Mailing List                    [hidden email]
> Automated List Manager                           [hidden email]
>
______________________________________________________________________
OpenSSL Project                                 http://www.openssl.org
User Support Mailing List                    [hidden email]
Automated List Manager                           [hidden email]