|
Science Forum Index » Cryptography Forum » Calculating entropy of randomness?
Page 1 of 1
|
| Author |
Message |
| CipherGuy |
 Posted: Mon Jan 26, 2004 10:29 am |
|
|
|
Guest
|
How to check that the PRNG key or the cipher text is truly random? Are
there any algorithms to check entropy of randomness? |
|
|
| Back to top |
|
| Douglas A. Gwyn |
| Posted: Mon Jan 26, 2004 7:38 pm |
|
|
|
Guest
|
CipherGuy wrote:
Quote: How to check that the PRNG key or the cipher text is truly random? Are
there any algorithms to check entropy of randomness?
/* checkit -- determine if ciphertext is truly random */
#include <stdio.h>
int main(void) {
printf("Nope.\n");
return 0;
} |
|
|
| Back to top |
|
| Matthew Skala |
| Posted: Tue Jan 27, 2004 9:05 pm |
|
|
|
Guest
|
In article <dd8cf7d7.0401260729.9e93938@posting.google.com>,
CipherGuy <cipherguy@37.com> wrote:
Quote: Are there any algorithms to check entropy of randomness?
About as many as there are to check the randomness of entropy. |
|
|
| Back to top |
|
| CipherGuy |
| Posted: Wed Jan 28, 2004 7:49 am |
|
|
|
Guest
|
"Douglas A. Gwyn" <DAGwyn@null.net> wrote in message news:<R82dnWfmMu-ULojdRVn-jA@comcast.com>...
Quote: CipherGuy wrote:
How to check that the PRNG key or the cipher text is truly random? Are
there any algorithms to check entropy of randomness?
/* checkit -- determine if ciphertext is truly random */
#include <stdio.h
int main(void) {
printf("Nope.\n");
return 0;
}
#include <seriousness.head>
#include <standout.h>
Fill void main()
{
int SeriousPercent;
printf("Thanks Douglas, for your nice C program.");
printf("Enter your seriousness: \n");
scanf("%d", &SeriousPercent);
if (SeriousPercent == 0)
printf("Don't Reply messages");
else
printf("Reply whatever you know");
} |
|
|
| Back to top |
|
| Richard Heathfield |
| Posted: Wed Jan 28, 2004 9:48 am |
|
|
|
Guest
|
CipherGuy wrote:
Quote: "Douglas A. Gwyn" <DAGwyn@null.net> wrote in message
news:<R82dnWfmMu-ULojdRVn-jA@comcast.com>...
CipherGuy wrote:
How to check that the PRNG key or the cipher text is truly random? Are
there any algorithms to check entropy of randomness?
/* checkit -- determine if ciphertext is truly random */
#include <stdio.h
int main(void) {
printf("Nope.\n");
return 0;
}
#include <seriousness.head
#include <standout.h
Fill void main()
{
int SeriousPercent;
printf("Thanks Douglas, for your nice C program.");
printf("Enter your seriousness: \n");
scanf("%d", &SeriousPercent);
if (SeriousPercent == 0)
printf("Don't Reply messages");
else
printf("Reply whatever you know");
}
Isn't it obvious that he's 100% serious?
A PRNG works by taking a given state and mutating it, via a fixed algorithm,
into a different state. If you know the first state and the algorithm, you
can predict the second state with 100% correctness. Therefore, it should be
transparently obvious that PRNGs do not produce random numbers, for any
reasonably strict interpretation of the word.
As for ciphertext, many algorithms will produce ciphertexts that are
indistinguishable from random bunches of bits, and yet those ciphertexts
were not generated randomly. So you simply can't tell whether a given bunch
of apparently random bits was produced randomly or deterministically.
--
Richard Heathfield : binary@eton.powernet.co.uk
"Usenet is a strange place." - Dennis M Ritchie, 29 July 1999.
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html
K&R answers, C books, etc: http://users.powernet.co.uk/eton |
|
|
| Back to top |
|
| Larry Hammick |
| Posted: Wed Jan 28, 2004 12:08 pm |
|
|
|
Guest
|
"CipherGuy"
Quote: How to check that the PRNG key or the cipher text is truly random? Are
there any algorithms to check entropy of randomness?
This discusses "deterministic" pseudorandom generators:
http://csrc.nist.gov/CryptoToolkit/tkrng.html
NIST is a worthwhile site to know about, anyway.
For really random data, just rent a Geiger counter and a tape recorder 
LH |
|
|
| Back to top |
|
| |
