/*
* aes_tables.c
*
* generate tables for the AES cipher
*
* David A. McGrew
* Cisco Systems, Inc.
*/
/*
*
* Copyright(c) 2001-2006 Cisco Systems, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
*
* Neither the name of the Cisco Systems, Inc. nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include <stdio.h>
#include "gf2_8.h"
#include "crypto_math.h"
unsigned char aes_sbox[256];
unsigned char aes_inv_sbox[256];
uint32_t T0[256], T1[256], T2[256], T3[256], T4[256];
#define AES_INVERSE_TEST 0 /* set to 1 to test forward/backwards aes */
/* functions for precomputing AES values */
/*
* A[] is the 8 x 8 binary matrix (represented as an array of columns,
* where each column is an octet) which defines the affine
* transformation used in the AES substitution table (Section
* 4.2.1 of the spec).
*/
uint8_t A[8] = { 31, 62, 124, 248, 241, 227, 199, 143 };
/*
* b is the 8 bit vector (represented as an octet) used in the affine
* transform described above.
*/
uint8_t b = 99;
void
aes_init_sbox(void) {
unsigned int i;
uint8_t x;
for (i=0; i < 256; i++) {
x = gf2_8_compute_inverse((gf2_8)i);
x = A_times_x_plus_b(A, x, b);
aes_sbox[i] = x;
aes_inv_sbox[x] = i;
}
}
void
aes_compute_tables(void) {
int i;
uint32_t x1, x2, x3;
v32_t tmp;
/* initialize substitution table */
aes_init_sbox();
/* combine sbox with linear operations to form 8-bit to 32-bit tables */
for (i=0; i < 256; i++) {
x1 = aes_sbox[i];
x2 = gf2_8_shift(x1);
x3 = x2 ^ x1;
tmp.v8[0] = x2;
tmp.v8[1] = x1;
tmp.v8[2] = x1;
tmp.v8[3] = x3;
T0[i] = tmp.value;
tmp.v8[0] = x3;
tmp.v8[1] = x2;
tmp.v8[2] = x1;
tmp.v8[3] = x1;
T1[i] = tmp.value;
tmp.v8[0] = x1;
tmp.v8[1] = x3;
tmp.v8[2] = x2;
tmp.v8[3] = x1;
T2[i] = tmp.value;
tmp.v8[0] = x1;
tmp.v8[1] = x1;
tmp.v8[2] = x3;
tmp.v8[3] = x2;
T3[i] = tmp.value;
}
}
/*
* the tables U0, U1, U2, U3 implement the aes operations invSubBytes,
* invMixColumns, and invShiftRows
*/
uint32_t U0[256], U1[256], U2[256], U3[256], U4[256];
extern uint8_t aes_inv_sbox[256];
void
aes_compute_inv_tables(void) {
int i;
uint8_t x, xe, x9, xd, xb;
v32_t tmp;
/* combine sbox with linear operations to form 8-bit to 32-bit tables */
for (i=0; i < 256; i++) {
x = aes_inv_sbox[i];
xe = gf2_8_multiply(0x0e, x);
x9 = gf2_8_multiply(0x09, x);
xd = gf2_8_multiply(0x0d, x);
xb = gf2_8_multiply(0x0b, x);
tmp.v8[0] = xe;
tmp.v8[1] = x9;
tmp.v8[2] = xd;
tmp.v8[3] = xb;
U0[i] = tmp.value;
tmp.v8[0] = xb;
tmp.v8[1] = xe;
tmp.v8[2] = x9;
tmp.v8[3] = xd;
U1[i] = tmp.value;
tmp.v8[0] = xd;
tmp.v8[1] = xb;
tmp.v8[2] = xe;
tmp.v8[3] = x9;
U2[i] = tmp.value;
tmp.v8[0] = x9;
tmp.v8[1] = xd;
tmp.v8[2] = xb;
tmp.v8[3] = xe;
U3[i] = tmp.value;
tmp.v8[0] = tmp.v8[1] = tmp.v8[2] = tmp.v8[3] = x;
U4[i] = tmp.value;
}
}
/*
* aes_test_inverse() returns err_status_ok if aes
* encryption and decryption are true inverses of each other, and
* returns err_status_algo_fail otherwise
*/
#include "err.h"
err_status_t
aes_test_inverse(void);
#define TABLES_32BIT 1
#ifndef HIDE_AES_TABLES_MAIN
int
main(void) {
int i;
aes_init_sbox();
aes_compute_inv_tables();
#if TABLES_32BIT
printf("uint32_t U0 = {");
for (i=0; i < 256; i++) {
if ((i % 4) == 0)
printf("\n");
printf("0x%0x, ", U0[i]);
}
printf("\n}\n");
printf("uint32_t U1 = {");
for (i=0; i < 256; i++) {
if ((i % 4) == 0)
printf("\n");
printf("0x%x, ", U1[i]);
}
printf("\n}\n");
printf("uint32_t U2 = {");
for (i=0; i < 256; i++) {
if ((i % 4) == 0)
printf("\n");
printf("0x%x, ", U2[i]);
}
printf("\n}\n");
printf("uint32_t U3 = {");
for (i=0; i < 256; i++) {
if ((i % 4) == 0)
printf("\n");
printf("0x%x, ", U3[i]);
}
printf("\n}\n");
printf("uint32_t U4 = {");
for (i=0; i < 256; i++) {
if ((i % 4) == 0)
printf("\n");
printf("0x%x, ", U4[i]);
}
printf("\n}\n");
#else
printf("uint32_t U0 = {");
for (i=0; i < 256; i++) {
if ((i % 4) == 0)
printf("\n");
printf("0x%lx, ", U0[i]);
}
printf("\n}\n");
printf("uint32_t U1 = {");
for (i=0; i < 256; i++) {
if ((i % 4) == 0)
printf("\n");
printf("0x%lx, ", U1[i]);
}
printf("\n}\n");
printf("uint32_t U2 = {");
for (i=0; i < 256; i++) {
if ((i % 4) == 0)
printf("\n");
printf("0x%lx, ", U2[i]);
}
printf("\n}\n");
printf("uint32_t U3 = {");
for (i=0; i < 256; i++) {
if ((i % 4) == 0)
printf("\n");
printf("0x%lx, ", U3[i]);
}
printf("\n}\n");
printf("uint32_t U4 = {");
for (i=0; i < 256; i++) {
if ((i % 4) == 0)
printf("\n");
printf("0x%lx, ", U4[i]);
}
printf("\n}\n");
#endif /* TABLES_32BIT */
#if AES_INVERSE_TEST
/*
* test that aes_encrypt and aes_decrypt are actually
* inverses of each other
*/
printf("aes inverse test: ");
if (aes_test_inverse() == err_status_ok)
printf("passed\n");
else {
printf("failed\n");
exit(1);
}
#endif
return 0;
}
#endif // HIDE_AES_TABLES_MAIN
#if AES_INVERSE_TEST
err_status_t
aes_test_inverse(void) {
v128_t x, y;
aes_expanded_key_t expanded_key, decrypt_key;
uint8_t plaintext[16] = {
0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff
};
uint8_t key[16] = {
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f
};
v128_t k;
v128_set_to_zero(&x);
v128_copy_octet_string(&k, key);
v128_copy_octet_string(&x, plaintext);
aes_expand_encryption_key(k, expanded_key);
aes_expand_decryption_key(k, decrypt_key);
aes_encrypt(&x, expanded_key);
aes_decrypt(&x, decrypt_key);
/* compare to expected value then report */
v128_copy_octet_string(&y, plaintext);
if (v128_is_eq(&x, &y))
return err_status_ok;
return err_status_algo_fail;
}
#endif