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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