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Questions tagged [isaac]

Questions about ISAAC stream cipher.

ISAAC is an array-based pseudorandom number generator designed by Robert J. Jenkins Jr. in 1993. ISAAC derived from the generators IA and IBAA. It has received relatively little scrutiny for security.

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Is ISAAC considered secure as a cryptographic random number generator?

The ISAAC site claims it is secure, but I wasn't aware of any trusted 3rd party sources that verified its security.
Jim McKeeth
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Is ISAAC Cipher Cryptographically Secure?

http://en.wikipedia.org/wiki/ISAAC_(cipher) This question was asked before but the answers seem vague, and I want to know about ISAAC specifically, not ISAAC+. It seems some cryptanalysis was performed on it and the only seemingly major drawback to…
user3100783
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Fast crytographically secure Pseudo-Random number generator in software

What are the methods for generating pseudo-random numbers in software? I have seen methods where people use SHA implementations from openssl to hash a random message as source of entropy, or using AES or Keccak. But I have done some experiments and…
Rick
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How secure is my OTP program?

I'm writing a one-time pad encryption program because I got really interested in the idea of "encryption which has been proven to be impossible to crack if used correctly". I'm writing the program just for fun, as programming and cryptography are…
Janman
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Is the output of ISAAC still secure if I take the 32 bit number mod 8?

I'm using ISAAC for encryption but only need an 8 bit number. So, if I use N mod 255, I presume the output would be only a random sequence of 255 numbers... but is it still secure? I could of course copy the 8 bit number to be encrypted into the…
Bipman
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Why is ISAAC not a pseudo random number generator?

I have been accused of confusion over the nature of the ISAAC algorithm. The bulk of evidence suggests that it is a cryptographically strong pseudo random number generator. By bulk I mean the number of authoritative references pointed to by a…
Paul Uszak
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Maximum security strength in bits of ISAAC cipher?

Wikipedia claims key length can be very big in this cipher, so I assume it can offer a million bits of security provided entropy of key is the same? Of course I can SHA-256 hash the key to allow any key sizes for AES... but it defeats the whole…
Mini kute
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Isaac nth number from run

Is there a way of getting the nth random number from a particular seed run in ISAAC? i.e. one day run a selection of 256 numbers and the next day run from the 256th number to get the next 256 random numbers? I presume no as I haven't been able to…
Bipman
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Is ISAAC+ actually an improvement over ISAAC?

I just tried to implement ISAAC from scratch, using the Jean-Philippe Aumasson paper from 2007 as a reference. This paper gives a definition of the original ISAAC algorithm as well as the improved ISAAC+ algorithm. JPA states in this paper that…
Guenther Brunthaler
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Key scheduling for ISAAC

Does ISAAC use key scheduling? I do not know programming. Is it safe if ISAAC derives subkeys using ISAAC itself?
Mini kute
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What is the purpose of ISAAC's randinit() function?

I am a relative crypto noob; please aim your answers accordingly. :) I'm planning to port the ISAAC CSPRNG algorithm to modern C++. I'm looking at Bob Jenkins' reference implementations: http://burtleburtle.net/bob/rand/isaacafa.html As I understand…
Quuxplusone
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Does ISAAC really guarantee a cycle length of at least 2**40?

I just noticed that the FSE 1996 conference paper which defines ISAAC mentions a counter variable cc. This variable is said to be the reason why ISAAC has a guaranteed minimum cycle length of $2^{40}$. However, no-one seems to have noticed (until I…
Guenther Brunthaler
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