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Re: Strong Crypto Support for GRUB2

From: Patrick Georgi
Subject: Re: Strong Crypto Support for GRUB2
Date: Mon, 03 Sep 2007 11:42:53 +0200
User-agent: Thunderbird 2.0b2 (X11/20070411)

Robert Millan schrieb:
+ * Forward S-box
+ */
+static const uint8 FSb[256] =
+    0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5,
+    0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB, 0x76,
+    0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0,
+    0x9B, 0x1E, 0x87, 0xE9, 0xCE, 0x55, 0x28, 0xDF,
+    0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68,
+    0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB, 0x16

This (and similar binary blobs) seems like a problem.  What do these numbers
mean?  If the spec defines a simple algorithm to generate them, a comment
with its implementation would be nice to have (e.g. like in md5sum.c from
It's the common distribution form, and not supposed to be edited, as the algorithm relies on that particular table layout.

from the header of that file:
>> + *  FIPS-197 compliant AES implementation
reasonably states where to get it from - maybe extend it with as an actual pointer, and that table with "taken from page 16 of the spec"

The original AES paper defined some criteria on s-box design and a bunch of equations on how they do it - but that's not enough information to create _this_ particular (ie. the standard's) table.

Patrick Georgi

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