Making a PRNG cryptographically secure
Hello, For Pseudo Random Numbers Generator based on linear recurrences, using SHA-1 over the PRNG's output appears to be the mostly common approach to make the output cryptographically secure. Are there any approaches that is not as computationally intensive as passing it over SHA-1/other block ciphers such that the output is cryptographically secure. Cryptographically secure as in the output sequence cannot be predicted to the left or right, given a substantially long subsequence of the output. Thank you, Sarad. ____________________________________________________________________________________ Looking for last minute shopping deals? Find them fast with Yahoo! Search. http://tools.search.yahoo.com/newsearch/category.php?category=shopping
Sarad AV <jtrjtrjtr2001@yahoo.com> wrote:
For Pseudo Random Numbers Generator based on linear recurrences, using SHA-1 over the PRNG's output appears to be the mostly common approach to make the output cryptographically secure.
Are you committed to a particular RNG? Blum Blum Shub is rather computationally intensive, but it may be less so than decorrelating some other PRNG with a hash. -=rsw
--- "Riad S. Wahby" <rsw@jfet.org> wrote:
Are you committed to a particular RNG? Blum Blum Shub is rather computationally intensive, but it may be less so than decorrelating some other PRNG with a hash.
No,any generator would do. BBS would be great but I am not worried of correlations here and would like the generator to be faster. Thanks though, will use it when the PRNG needs to be cryptographically secure and rather decorrelated. BBS's response to the diehard test is also good. I guess a PRNG passed over SHA-1 wouldn't pass the diehard test. http://www.pierssen.com/arcview/upload/esoterica/randomizer.html Sarad. ____________________________________________________________________________________ Looking for last minute shopping deals? Find them fast with Yahoo! Search. http://tools.search.yahoo.com/newsearch/category.php?category=shopping
hi, I am looking at single cycle, invertible permutation functions of the form x -> x+ (x^2 V C) (mod 2^n), where V is a bitwise OR and C is a special constant. This function is as given in the url below http://citeseer.ist.psu.edu/klimov02new.html Would like to find the inverse permutation function for it but the paper only shows that the above function is provably invertible. Are there any construction methods for finding inverse permutation function, for a single cycle invertible function f? Thanks, Sarad. ____________________________________________________________________________________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs
Dude: Just how long will you continue taking Grad courses? Hasn't it been like 10 years already? And I repeat: Cypherpunks deserves a permanent cut of your post-grad income. I say 10% will do... -TD
Date: Tue, 18 Mar 2008 13:59:36 -0700 From: jtrjtrjtr2001@yahoo.com Subject: Finding invertible permutation functions To: cypherpunks@al-qaeda.net
hi,
I am looking at single cycle, invertible permutation functions of the form x -> x+ (x^2 V C) (mod 2^n), where V is a bitwise OR and C is a special constant. This function is as given in the url below http://citeseer.ist.psu.edu/klimov02new.html
Would like to find the inverse permutation function for it but the paper only shows that the above function is provably invertible.
Are there any construction methods for finding inverse permutation function, for a single cycle invertible function f?
Thanks, Sarad.
_____________________________________________________________________________ _______
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_________________________________________________________________ More immediate than e-mail? Get instant access with Windows Live Messenger. http://www.windowslive.com/messenger/overview.html?ocid=TXT_TAGLM_WL_Refresh... instantaccess_042008
it's not for any grad course but lets cut a deal. i will send you free turkey and beer for every post where you don't bring this up :-) --- Tyler Durden <camera_lumina@hotmail.com> wrote:
Dude: Just how long will you continue taking Grad courses? Hasn't it been like 10 years already?
And I repeat: Cypherpunks deserves a permanent cut of your post-grad income. I say 10% will do...
-TD
Date: Tue, 18 Mar 2008 13:59:36 -0700 From: jtrjtrjtr2001@yahoo.com Subject: Finding invertible permutation functions To: cypherpunks@al-qaeda.net
hi,
I am looking at single cycle, invertible permutation functions of the form x -> x+ (x^2 V C) (mod 2^n), where V is a bitwise OR and C is a special constant. This function is as given in the url below http://citeseer.ist.psu.edu/klimov02new.html
Would like to find the inverse permutation function for it but the paper only shows that the above function is provably invertible.
Are there any construction methods for finding inverse permutation function, for a single cycle invertible function f?
Thanks, Sarad.
____________________________________________________________________________________
Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs
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More immediate than e-mail? Get instant access with Windows Live Messenger.
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participants (3)
-
Riad S. Wahby -
Sarad AV -
Tyler Durden