![[JoGu]](../../JGU.gif) |
Cryptology
Analysis of the S-Boxes of DES |
a7Hzq .#5r<
kÜ\as TâÆK$
ûj(Ö2 ñw%h:
Úk{4R f~`z8
¤˜Æ+Ô „&¢Dø |
|
| DES S-box: |
S1 | S2 |
S3 | S4 |
S5 | S6 |
S7 | S8 |
| linear potential: |
81/256 | 1/4 | 1/4 | 1/4 |
25/64 | 49/256 | 81/256 | 1/4 |
| differential potential: |
1/4 | 1/4 | 1/4 | 1/4 |
1/4 | 1/4 | 1/4 | 1/4 |
It was known since a long time—but if not we would see it now:
The designers of DES knew about differential cryptanalysis,
as is evident from the uniformly low differential potential. The somewhat chaotic
linear potential suggests the they didn't yet know about linear
cryptanalysis.
In particular the »bad« value
25/64 = 100/256 for S5 reveals a remarkable weakness.
Author: Klaus Pommerening, 2003-Jan-12;
last change: 2005-Jun-06.