# Tag Info

## New answers tagged format-preserving

2

Is this true? Are block ciphers considered to be FPE? Well not exactly . Its something more than block ciphers. Of course block ciphers are integral to FPE. Some times we need to preserve the lengths but some times we need to preserve the lengths of encoded strings. Lets see some examples. Informally, In order to preserve the formats of input data types ...

3

The formal definition of a block cipher is a function $$E_K(P) := E(K, P): \{0,1\}^k \times \{0,1\}^n \rightarrow \{0,1\}^n$$ The input and output spaces are by definition n-bit blocks, so the operation of the cipher in Electronic Code Book (ECB) mode is technically "format preserving". That is not however what "Format Preserving Encryption" (FPE) ...

2

I explain, criticize and try to improve the technique in the question (which asks for speed by using cryptographic techniques for arguably satisfactory functionality in a statistical simulation). Shuffling, and full-blown Format-Preserving Encryption aim at perfect or demonstrable cryptographic security, a different goal. Under the assumption that the ...

4

Use format-preserving encryption. The current NIST standards-track mode FFX should be sufficiently fast for your purposes. For your domain size, you might also want to try the swap-or-not shuffle, a new construction which is also pretty fast and dead simple to implement. To get the absolute best speed form these schemes you should use a single AES call as ...

1

The theoretically correct random permutation algorithem is IMHO uniquely that of Fisher and Yates [1], which needs for performing a permutation of a sequence of n items n-1 PRNs. I perviously found that a practically fairly passable result could also be achieved with 2 PRNs [2]. [1] D. E. Knuth, The Art of Computer Programming, Vol. 2, 3rd ed. p.145. [2] ...

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