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Format preserving encryption has three modes FE1( FFX) , FE2(VAES) , FE3(BPS) . All of them are based on Feistel Networks .Can somebody explain how they differ from each other ?

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It's even worse, FFX contains several different modes plus a bunch of parameters. – CodesInChaos Nov 8 '13 at 13:26
up vote 2 down vote accepted

Ff1,2,3 are basically inspired by LubyRack off constructions . At the core they differ in their round functions and key scheduling

FF1 supports greater range of lengths and a tweak

FF2 generates subkey for each iteration to thwart any side channel attacks

FF3 has tweaks is split and used in rounding function, also the reverse the sub-strings of given input string while using in round function,

Both FF1,FF2 has 10 rounds FF3 has only 8 rounds

Read more at NIST's 800 38 G draft

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How do you decide which mode to use? – erotavlas Apr 30 '15 at 20:07
depends you need to pick on your requirements. you need greater range of lengths of formats or performance etc. – sashank May 1 '15 at 16:38

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