aestab.c

使用visual studio 2005 开发的开源文件、磁盘加密软件。这是6.1a版。加密自己资料的好工具。也是学习的优秀范本。结成了众多加密算法。

/*  return 2 ^ (n - 1) where n is the bit number of the highest bit
    set in x with x in the range 1 < x < 0x00000200.   This form is
    used so that locals within fi can be bytes rather than words
*/

static uint_8t hibit(const uint_32t x)
{   uint_8t r = (uint_8t)((x >> 1) | (x >> 2));

    r |= (r >> 2);
    r |= (r >> 4);
    return (r + 1) >> 1;
}

/* return the inverse of the finite field element x */

static uint_8t fi(const uint_8t x)
{   uint_8t p1 = x, p2 = BPOLY, n1 = hibit(x), n2 = 0x80, v1 = 1, v2 = 0;

    if(x < 2) return x;

    for(;;)
    {
        if(!n1) return v1;

        while(n2 >= n1)
        {
            n2 /= n1; p2 ^= p1 * n2; v2 ^= v1 * n2; n2 = hibit(p2);
        }

        if(!n2) return v2;

        while(n1 >= n2)
        {
            n1 /= n2; p1 ^= p2 * n1; v1 ^= v2 * n1; n1 = hibit(p1);
        }
    }
}

#endif

/* The forward and inverse affine transformations used in the S-box */

#define fwd_affine(x) \
    (w = (uint_32t)x, w ^= (w<<1)^(w<<2)^(w<<3)^(w<<4), 0x63^(uint_8t)(w^(w>>8)))

#define inv_affine(x) \
    (w = (uint_32t)x, w = (w<<1)^(w<<3)^(w<<6), 0x05^(uint_8t)(w^(w>>8)))

static int init = 0;

#ifdef TC_WINDOWS_BOOT

#pragma optimize ("l", on)
uint_8t aes_enc_tab[256][8];
uint_8t aes_dec_tab[256][8];

#endif

AES_RETURN aes_init(void)
{   uint_32t  i, w;

#ifdef TC_WINDOWS_BOOT

	if (init)
		return EXIT_SUCCESS;

    for (i = 0; i < 256; ++i)
    { 
        uint_8t x = fwd_affine(fi((uint_8t)i));
		aes_enc_tab[i][0] = 0;
		aes_enc_tab[i][1] = x;
		aes_enc_tab[i][2] = x;
		aes_enc_tab[i][3] = f3(x);
		aes_enc_tab[i][4] = f2(x);
		aes_enc_tab[i][5] = x;
		aes_enc_tab[i][6] = x;
		aes_enc_tab[i][7] = f3(x);

        x = fi((uint_8t)inv_affine((uint_8t)i));
		aes_dec_tab[i][0] = fe(x);
		aes_dec_tab[i][1] = f9(x);
		aes_dec_tab[i][2] = fd(x);
		aes_dec_tab[i][3] = fb(x);
		aes_dec_tab[i][4] = fe(x);
		aes_dec_tab[i][5] = f9(x);
		aes_dec_tab[i][6] = fd(x);
		aes_dec_tab[i][7] = x;
    }

#else // TC_WINDOWS_BOOT

#if defined(FF_TABLES)

    uint_8t  pow[512], log[256];

    if(init)
        return EXIT_SUCCESS;
    /*  log and power tables for GF(2^8) finite field with
        WPOLY as modular polynomial - the simplest primitive
        root is 0x03, used here to generate the tables
    */

    i = 0; w = 1;
    do
    {
        pow[i] = (uint_8t)w;
        pow[i + 255] = (uint_8t)w;
        log[w] = (uint_8t)i++;
        w ^=  (w << 1) ^ (w & 0x80 ? WPOLY : 0);
    }
    while (w != 1);

#else
    if(init)
        return EXIT_SUCCESS;
#endif

    for(i = 0, w = 1; i < RC_LENGTH; ++i)
    {
        t_set(r,c)[i] = bytes2word(w, 0, 0, 0);
        w = f2(w);
    }

    for(i = 0; i < 256; ++i)
    {   uint_8t    b;

        b = fwd_affine(fi((uint_8t)i));
        w = bytes2word(f2(b), b, b, f3(b));

#if defined( SBX_SET )
        t_set(s,box)[i] = b;
#endif

#if defined( FT1_SET )                 /* tables for a normal encryption round */
        t_set(f,n)[i] = w;
#endif
#if defined( FT4_SET )
        t_set(f,n)[0][i] = w;
        t_set(f,n)[1][i] = upr(w,1);
        t_set(f,n)[2][i] = upr(w,2);
        t_set(f,n)[3][i] = upr(w,3);
#endif
        w = bytes2word(b, 0, 0, 0);

#if defined( FL1_SET )            /* tables for last encryption round (may also   */
        t_set(f,l)[i] = w;        /* be used in the key schedule)                 */
#endif
#if defined( FL4_SET )
        t_set(f,l)[0][i] = w;
        t_set(f,l)[1][i] = upr(w,1);
        t_set(f,l)[2][i] = upr(w,2);
        t_set(f,l)[3][i] = upr(w,3);
#endif

#if defined( LS1_SET )			/* table for key schedule if t_set(f,l) above is*/
        t_set(l,s)[i] = w;      /* not of the required form                     */
#endif
#if defined( LS4_SET )
        t_set(l,s)[0][i] = w;
        t_set(l,s)[1][i] = upr(w,1);
        t_set(l,s)[2][i] = upr(w,2);
        t_set(l,s)[3][i] = upr(w,3);
#endif

        b = fi(inv_affine((uint_8t)i));
        w = bytes2word(fe(b), f9(b), fd(b), fb(b));

#if defined( IM1_SET )			/* tables for the inverse mix column operation  */
        t_set(i,m)[b] = w;
#endif
#if defined( IM4_SET )
        t_set(i,m)[0][b] = w;
        t_set(i,m)[1][b] = upr(w,1);
        t_set(i,m)[2][b] = upr(w,2);
        t_set(i,m)[3][b] = upr(w,3);
#endif

#if defined( ISB_SET )
        t_set(i,box)[i] = b;
#endif
#if defined( IT1_SET )			/* tables for a normal decryption round */
        t_set(i,n)[i] = w;
#endif
#if defined( IT4_SET )
        t_set(i,n)[0][i] = w;
        t_set(i,n)[1][i] = upr(w,1);
        t_set(i,n)[2][i] = upr(w,2);
        t_set(i,n)[3][i] = upr(w,3);
#endif
        w = bytes2word(b, 0, 0, 0);
#if defined( IL1_SET )			/* tables for last decryption round */
        t_set(i,l)[i] = w;
#endif
#if defined( IL4_SET )
        t_set(i,l)[0][i] = w;
        t_set(i,l)[1][i] = upr(w,1);
        t_set(i,l)[2][i] = upr(w,2);
        t_set(i,l)[3][i] = upr(w,3);
#endif
    }

#endif // TC_WINDOWS_BOOT

    init = 1;
    return EXIT_SUCCESS;
}

#endif

#if defined(__cplusplus)
}
#endif