[cryptography] any info on (format-preserving) random permutation algorithms in java?

Francois Grieu fgrieu at gmail.com
Tue Mar 19 05:49:31 EDT 2013

On 19/03/2013 00:50, travis+ml-rbcryptography at subspacefield.org wrote:
 > So, my problem is to create a format-preserving injective function
 > which is non-invertible (at least computationally).
 > Since it's format preserving, it has to be a bijection, I'm guessing
 > that basically boils down to a (computationally strong?) random
 > permutation, for a domain of size =/= 2^n.

A hash with n-bit result, with input domain restricted to n-bit,
with n>=200 or so, is not a bijection, but is computationally
indistinguishable from what Iunderstand is your requirement.
Do I miss something?Or do you want it to be demonstrably
format-preserving/bijective(rather than computationally
indistinguishable from that)?

http://crypto.stackexchange.com would be another nice place to ask.

   Francois Grieu

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