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Commit 1edfd54d authored by Niels Möller's avatar Niels Möller
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* aes-set-key.c (aes_set_key): Deleted file, code moved... 

* aes-set-decrypt-key.c, aes-set-encrypt-key.c: New files,
separated normal and inverse key setup.

Rev: src/nettle/aes-set-key.c:1.4(DEAD)
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/* aes-set-key.c
*
* Key setup for the aes/rijndael block cipher.
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2000, 2001 Rafael R. Sevilla, Niels Mller
*
* The nettle library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at your
* option) any later version.
*
* The nettle library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with the nettle library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
/* Originally written by Rafael R. Sevilla <dido@pacific.net.ph> */
#include "aes-internal.h"
#include <assert.h>
/* Used only by the key schedule */
static const uint8_t Logtable[256] = {
0, 0, 25, 1, 50, 2, 26, 198, 75, 199, 27, 104, 51, 238, 223, 3,
100, 4, 224, 14, 52, 141, 129, 239, 76, 113, 8, 200, 248, 105, 28,
193, 125, 194, 29, 181, 249, 185, 39, 106, 77, 228, 166, 114, 154, 201,
9, 120, 101, 47, 138, 5, 33, 15, 225, 36, 18, 240, 130, 69, 53,
147, 218, 142, 150, 143, 219, 189, 54, 208, 206, 148, 19, 92, 210, 241,
64, 70, 131, 56, 102, 221, 253, 48, 191, 6, 139, 98, 179, 37, 226,
152, 34, 136, 145, 16, 126, 110, 72, 195, 163, 182, 30, 66, 58, 107,
40, 84, 250, 133, 61, 186, 43, 121, 10, 21, 155, 159, 94, 202, 78,
212, 172, 229, 243, 115, 167, 87, 175, 88, 168, 80, 244, 234, 214, 116,
79, 174, 233, 213, 231, 230, 173, 232, 44, 215, 117, 122, 235, 22, 11,
245, 89, 203, 95, 176, 156, 169, 81, 160, 127, 12, 246, 111, 23, 196,
73, 236, 216, 67, 31, 45, 164, 118, 123, 183, 204, 187, 62, 90, 251,
96, 177, 134, 59, 82, 161, 108, 170, 85, 41, 157, 151, 178, 135, 144,
97, 190, 220, 252, 188, 149, 207, 205, 55, 63, 91, 209, 83, 57, 132,
60, 65, 162, 109, 71, 20, 42, 158, 93, 86, 242, 211, 171, 68, 17,
146, 217, 35, 32, 46, 137, 180, 124, 184, 38, 119, 153, 227, 165, 103,
74, 237, 222, 197, 49, 254, 24, 13, 99, 140, 128, 192, 247, 112, 7,
};
static const uint8_t Alogtable[256] = {
1, 3, 5, 15, 17, 51, 85, 255, 26, 46, 114, 150, 161, 248, 19,
53, 95, 225, 56, 72, 216, 115, 149, 164, 247, 2, 6, 10, 30, 34,
102, 170, 229, 52, 92, 228, 55, 89, 235, 38, 106, 190, 217, 112, 144,
171, 230, 49, 83, 245, 4, 12, 20, 60, 68, 204, 79, 209, 104, 184,
211, 110, 178, 205, 76, 212, 103, 169, 224, 59, 77, 215, 98, 166, 241,
8, 24, 40, 120, 136, 131, 158, 185, 208, 107, 189, 220, 127, 129, 152,
179, 206, 73, 219, 118, 154, 181, 196, 87, 249, 16, 48, 80, 240, 11,
29, 39, 105, 187, 214, 97, 163, 254, 25, 43, 125, 135, 146, 173, 236,
47, 113, 147, 174, 233, 32, 96, 160, 251, 22, 58, 78, 210, 109, 183,
194, 93, 231, 50, 86, 250, 21, 63, 65, 195, 94, 226, 61, 71, 201,
64, 192, 91, 237, 44, 116, 156, 191, 218, 117, 159, 186, 213, 100, 172,
239, 42, 126, 130, 157, 188, 223, 122, 142, 137, 128, 155, 182, 193, 88,
232, 35, 101, 175, 234, 37, 111, 177, 200, 67, 197, 84, 252, 31, 33,
99, 165, 244, 7, 9, 27, 45, 119, 153, 176, 203, 70, 202, 69, 207,
74, 222, 121, 139, 134, 145, 168, 227, 62, 66, 198, 81, 243, 14, 18,
54, 90, 238, 41, 123, 141, 140, 143, 138, 133, 148, 167, 242, 13, 23,
57, 75, 221, 124, 132, 151, 162, 253, 28, 36, 108, 180, 199, 82, 246, 1,
};
static uint8_t
xtime(uint8_t a)
{
uint8_t b;
b = (a & 0x80) ? 0x1b : 0;
a<<=1;
a^=b;
return(a);
}
static uint8_t
mul(uint8_t a, uint8_t b)
{
if (a && b) return Alogtable[(Logtable[a] + Logtable[b])%255];
else return 0;
}
static void
inv_mix_column(const uint32_t *a, uint32_t *b)
{
uint8_t c[4][4];
unsigned i, j;
for(j = 0; j < 4; j++)
{
for(i = 0; i < 4; i++)
{
c[j][i] = mul(0xe, (a[j] >> i*8) & 0xff)
^ mul(0xb, (a[j] >> ((i+1)%4)*8) & 0xff)
^ mul(0xd, (a[j] >> ((i+2)%4)*8) & 0xff)
^ mul(0x9, (a[j] >> ((i+3)%4)*8) & 0xff);
}
}
for(i = 0; i < 4; i++)
{
b[i] = 0;
for(j = 0; j < 4; j++)
b[i] |= c[i][j] << (j*8);
}
}
/* FIXME: Perhaps we should have separate fucntion for encryption and
* decryption keys? It seems unnecessary to compute the inverse
* subkeys if we're not going to use them. Can one define an
* aes_inverse function? */
void
aes_set_key(struct aes_ctx *ctx, unsigned keysize, const uint8_t *key)
{
unsigned nk, nr, i, lastkey;
uint32_t temp, rcon;
assert(keysize >= AES_MIN_KEY_SIZE);
assert(keysize <= AES_MAX_KEY_SIZE);
/* Truncate keysizes to the valid key sizes provided by Rijndael */
if (keysize == 32) {
nk = 8;
nr = 14;
} else if (keysize >= 24) {
nk = 6;
nr = 12;
} else { /* must be 16 or more */
nk = 4;
nr = 10;
}
lastkey = (AES_BLOCK_SIZE/4) * (nr + 1);
ctx->nrounds = nr;
rcon = 1;
for (i=0; i<nk; i++)
{
ctx->keys[i] = key[i*4] + (key[i*4+1]<<8) + (key[i*4+2]<<16) +
(key[i*4+3]<<24);
}
for (i=nk; i<lastkey; i++)
{
temp = ctx->keys[i-1];
if (i % nk == 0)
{
temp = SUBBYTE(ROTBYTE(temp), sbox) ^ rcon;
rcon = (uint32_t)xtime((uint8_t)rcon&0xff);
}
else if (nk > 6 && (i%nk) == 4)
{
temp = SUBBYTE(temp, sbox);
}
ctx->keys[i] = ctx->keys[i-nk] ^ temp;
}
/* Generate the inverse keys */
for (i=0; i<4; i++)
{
ctx->ikeys[i] = ctx->keys[lastkey-4 + i];
ctx->ikeys[lastkey-4 + i] = ctx->keys[i];
}
for (i=4; i<lastkey-4; i+=4)
inv_mix_column(&(ctx->keys[i]), &(ctx->ikeys[lastkey-4 - i]));
}
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