# Quick Question About FEAL

*From*: MTGAP <mtgandp@xxxxxxxxx>*Date*: Sun, 19 Apr 2009 14:56:34 -0700 (PDT)

The official paper on FEAL doesn't have any detailed algorithm

description, and instead only has annoying diagrams. So I'm not sure I

have it correct. Does this pseudo-code accurately represent the FEAL f-

function?

-a0 denotes the first byte of a, a1 denotes the second, a2 the third,

etc.

-Since my keyboard has no exclusive-or key, I am using the ^ symbol to

represent exclusive-or.

- <<< denotes left rotation.

[code]

function f (int a, short b) {

a1 = a1 ^ b0 ^ a0;

a2 = a2 ^ b1 ^ a3;

a1 = S(a1, a2, 1);

a0 = S(a0, a1, 0);

a2 = S(a2, a1, 0);

a3 = S(a3, a2, 1);

return a;

}

function S (byte x, byte y, bool delta) {

return ((x + y + delta) mod 256) <<< 2;

}

[/code]

.

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