aes_ref_encr.c

RMI的处理器au1200系列所用的BOOTLOAD,包括SD卡启动USB启动硬盘启动网络启动,并初始化硬件的所有参数,支持内核调试.

/* rijndael-alg-ref.c   v2.0   August '99
 * Reference ANSI C code
 * authors: Paulo Barreto
 *          Vincent Rijmen
 *
 * (NIST AES reference version)
 * modification (no decryption, no encrypt round functions, 128 bit only):
 *	Reinhard Wobst, @(#) Sep 21 2004, 09:28:30
 *	This heavily reduced version is dedicated to the German
 *	ministry of finances.
 */

#include <stdio.h>
#include <stdlib.h>

#include "aes_ref_encr.h"
#include "boxes-ref.dat"

#define SC	((BC - 4) >> 1)

static word8 shifts[3][4][2] = {
    {
     {0, 0},
     {1, 3},
     {2, 2},
     {3, 1}
     },

    {
     {0, 0},
     {1, 5},
     {2, 4},
     {3, 3}
     },

    {
     {0, 0},
     {1, 7},
     {3, 5},
     {4, 4}
     }
};


/* multiply two elements of GF(2^m)
 * needed for MixColumn
 */

static word8 mul(word8 a, word8 b)
{
    if (a && b)
	return Alogtable[(Logtable[a] + Logtable[b]) % 255];
    else
	return 0;
}

/* Exor corresponding text input and round key input bytes */

static void KeyAddition(word8 a[4][MAXBC], word8 rk[4][MAXBC], word8 BC)
{
    int i, j;

    for (i = 0; i < 4; i++)
	for (j = 0; j < BC; j++)
	    a[i][j] ^= rk[i][j];
}

/* Row 0 remains unchanged
 * the other three rows are shifted a variable amount
 */

static void ShiftRow(word8 a[4][MAXBC], word8 d, word8 BC)
{
    word8 tmp[MAXBC];
    int i, j;

    for (i = 1; i < 4; i++) {
	for (j = 0; j < BC; j++)
	    tmp[j] = a[i][(j + shifts[SC][i][d]) % BC];
	for (j = 0; j < BC; j++)
	    a[i][j] = tmp[j];
    }
}

/* Replace every byte of the input by the byte at that place
 * in the nonlinear S-box
 */

static void Substitution(word8 a[4][MAXBC], word8 box[256], word8 BC)
{
    int i, j;

    for (i = 0; i < 4; i++)
	for (j = 0; j < BC; j++)
	    a[i][j] = box[a[i][j]];
}

/* Mix the four bytes of every column in a linear way */

static void MixColumn(word8 a[4][MAXBC], word8 BC)
{
    word8 b[4][MAXBC];
    int i, j;

    for (j = 0; j < BC; j++)
	for (i = 0; i < 4; i++)
	    b[i][j] = mul(2, a[i][j])
		^ mul(3, a[(i + 1) % 4][j])
		^ a[(i + 2) % 4][j]
		^ a[(i + 3) % 4][j];
    for (i = 0; i < 4; i++)
	for (j = 0; j < BC; j++)
	    a[i][j] = b[i][j];
}

/* Calculate the necessary round keys
 * The number of calculations depends on keyBits and blockBits
 */

int rijndaelKeySched(word8 k[4][MAXKC],
		     int keyBits, int blockBits,
		     word8 W[MAXROUNDS + 1][4][MAXBC])
{
    const int KC = 4;
    const int BC = 4;
    const int ROUNDS = 10;

    int i, j, t, rconpointer = 0;
    word8 tk[4][MAXKC];

    for (j = 0; j < KC; j++)
	for (i = 0; i < 4; i++)
	    tk[i][j] = k[i][j];
    t = 0;

    /* copy values into round key array */
    for (j = 0; (j < KC) && (t < (ROUNDS + 1) * BC); j++, t++)
	for (i = 0; i < 4; i++)
	    W[t / BC][i][t % BC] = tk[i][j];

    /* while not enough round key material calculated
     * calculate new values
     */

    while (t < (ROUNDS + 1) * BC) {
	for (i = 0; i < 4; i++)
	    tk[i][0] ^= S[tk[(i + 1) % 4][KC - 1]];
	tk[0][0] ^= rcon[rconpointer++];

	if (KC != 8)
	    for (j = 1; j < KC; j++)
		for (i = 0; i < 4; i++)
		    tk[i][j] ^= tk[i][j - 1];
	else {
	    for (j = 1; j < KC / 2; j++)
		for (i = 0; i < 4; i++)
		    tk[i][j] ^= tk[i][j - 1];
	    for (i = 0; i < 4; i++)
		tk[i][KC / 2] ^= S[tk[i][KC / 2 - 1]];
	    for (j = KC / 2 + 1; j < KC; j++)
		for (i = 0; i < 4; i++)
		    tk[i][j] ^= tk[i][j - 1];
	}

	/* copy values into round key array */
	for (j = 0; (j < KC) && (t < (ROUNDS + 1) * BC); j++, t++)
	    for (i = 0; i < 4; i++)
		W[t / BC][i][t % BC] = tk[i][j];
    }

    return 0;
}

int rijndaelEncrypt(word8 a[4][MAXBC],
		    int keyBits, int blockBits,
		    word8 rk[MAXROUNDS + 1][4][MAXBC])
{
    /* Encryption of one block. */
    int r, BC, ROUNDS;

    BC = 4;
    ROUNDS = 10;

    /* begin with a key addition */
    KeyAddition(a, rk[0], BC);

    /* ROUNDS-1 ordinary rounds */
    for (r = 1; r < ROUNDS; r++) {
	Substitution(a, (word8 *) S, BC);
	ShiftRow(a, 0, BC);
	MixColumn(a, BC);
	KeyAddition(a, rk[r], BC);
    }

    /* Last round is special: there is no MixColumn */
    Substitution(a, (word8 *) S, BC);
    ShiftRow(a, 0, BC);
    KeyAddition(a, rk[ROUNDS], BC);

    return 0;
}