/*
  Based on an implementation by 
  Dr Brian Gladman (gladman@seven77.demon.co.uk)
*/

#include <stdio.h>

#define rotr(x,n)   (((x) >> ((int)(n))) | ((x) << (32 - (int)(n))))
#define rotl(x,n)   (((x) << ((int)(n))) | ((x) >> (32 - (int)(n))))

/* Extract byte from a 32 bit quantity (little endian notation)     */ 

#define byte(x,n)   ((u1byte)((x) >> (8 * n)))

#ifdef GENTABS
u1byte  pow_tab[256];
u1byte  log_tab[256];
u1byte  sbx_tab[256];
u1byte  isb_tab[256];
u4byte  rco_tab[10];
u4byte  ft_tab[4][256];
u4byte  it_tab[4][256];
u4byte  fl_tab[4][256];
u4byte  il_tab[4][256];
#else
extern u1byte  pow_tab[];
extern u1byte  log_tab[];
extern u1byte  sbx_tab[];
extern u1byte  isb_tab[];
extern u4byte  rco_tab[];
extern u4byte  ft_tab[][256];
extern u4byte  it_tab[][256];
extern u4byte  fl_tab[][256];
extern u4byte  il_tab[][256];
#endif

#define ff_mult(a,b)    (a && b ? pow_tab[(log_tab[a] + log_tab[b]) % 255] : 0)

#define f_rn(bo, bi, n, k)                          \
    bo[n] =  ft_tab[0][byte(bi[n],0)] ^             \
             ft_tab[1][byte(bi[(n + 1) & 3],1)] ^   \
             ft_tab[2][byte(bi[(n + 2) & 3],2)] ^   \
             ft_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n)

#define i_rn(bo, bi, n, k)                          \
    bo[n] =  it_tab[0][byte(bi[n],0)] ^             \
             it_tab[1][byte(bi[(n + 3) & 3],1)] ^   \
             it_tab[2][byte(bi[(n + 2) & 3],2)] ^   \
             it_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n)

#define ls_box(x)                \
    ( fl_tab[0][byte(x, 0)] ^    \
      fl_tab[1][byte(x, 1)] ^    \
      fl_tab[2][byte(x, 2)] ^    \
      fl_tab[3][byte(x, 3)] )

#define f_rl(bo, bi, n, k)                          \
    bo[n] =  fl_tab[0][byte(bi[n],0)] ^             \
             fl_tab[1][byte(bi[(n + 1) & 3],1)] ^   \
             fl_tab[2][byte(bi[(n + 2) & 3],2)] ^   \
             fl_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n)

#define i_rl(bo, bi, n, k)                          \
    bo[n] =  il_tab[0][byte(bi[n],0)] ^             \
             il_tab[1][byte(bi[(n + 3) & 3],1)] ^   \
             il_tab[2][byte(bi[(n + 2) & 3],2)] ^   \
             il_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n)

#ifdef GENTABS

void gen_tabs(void)
{   u4byte  i, t;
 u1byte  p, q;

 /* log and power tables for GF(2**8) finite field with  */
 /* 0x11b as modular polynomial - the simplest prmitive  */
 /* root is 0x11, used here to generate the tables       */

 for(i = 0,p = 1; i < 256; ++i)
   {
     pow_tab[i] = (u1byte)p; log_tab[p] = (u1byte)i;

     p = p ^ (p << 1) ^ (p & 0x80 ? 0x01b : 0);
   }

 log_tab[1] = 0; p = 1;

 for(i = 0; i < 10; ++i)
   {
     rco_tab[i] = p; 

     p = (p << 1) ^ (p & 0x80 ? 0x1b : 0);
   }

 /* note that the affine byte transformation matrix in   */
 /* rijndael specification is in big endian format with  */
 /* bit 0 as the most significant bit. In the remainder  */
 /* of the specification the bits are numbered from the  */
 /* least significant end of a byte.                     */

 for(i = 0; i < 256; ++i)
   {   
     p = (i ? pow_tab[255 - log_tab[i]] : 0); q = p; 
     q = (q >> 7) | (q << 1); p ^= q; 
     q = (q >> 7) | (q << 1); p ^= q; 
     q = (q >> 7) | (q << 1); p ^= q; 
     q = (q >> 7) | (q << 1); p ^= q ^ 0x63; 
     sbx_tab[i] = (u1byte)p; isb_tab[p] = (u1byte)i;
   }

 for(i = 0; i < 256; ++i)
   {
     p = sbx_tab[i]; 

     t = p; fl_tab[0][i] = t;
     fl_tab[1][i] = rotl(t,  8);
     fl_tab[2][i] = rotl(t, 16);
     fl_tab[3][i] = rotl(t, 24);

     t = ((u4byte)ff_mult(2, p)) |
       ((u4byte)p <<  8) |
       ((u4byte)p << 16) |
       ((u4byte)ff_mult(3, p) << 24);
        
     ft_tab[0][i] = t;
     ft_tab[1][i] = rotl(t,  8);
     ft_tab[2][i] = rotl(t, 16);
     ft_tab[3][i] = rotl(t, 24);

     p = isb_tab[i]; 

     t = p; il_tab[0][i] = t; 
     il_tab[1][i] = rotl(t,  8); 
     il_tab[2][i] = rotl(t, 16); 
     il_tab[3][i] = rotl(t, 24);

     t = ((u4byte)ff_mult(14, p)) |
       ((u4byte)ff_mult( 9, p) <<  8) |
       ((u4byte)ff_mult(13, p) << 16) |
       ((u4byte)ff_mult(11, p) << 24);
        
     it_tab[0][i] = t; 
     it_tab[1][i] = rotl(t,  8); 
     it_tab[2][i] = rotl(t, 16); 
     it_tab[3][i] = rotl(t, 24); 
   }

};

main()
{
  FILE *tabf = fopen("rijndael_tables.c","wt");
  int i,j;

  gen_tabs();

  fprintf(tabf,"typedef unsigned u4byte;\n");
  fprintf(tabf,"typedef unsigned char u1byte;\n");

  fprintf(tabf,"u1byte pow_tab[] = {%uU",pow_tab[0]);
  for (i = 1; i < 256; i++) {
    fprintf(tabf,",%uU",pow_tab[i]);
  }
  fprintf(tabf,"};\n");

  fprintf(tabf,"u1byte log_tab[] = {%uU",log_tab[0]);
  for (i = 1; i < 256; i++) {
    fprintf(tabf,",%uU",log_tab[i]);
  }
  fprintf(tabf,"};\n");

  fprintf(tabf,"u1byte sbx_tab[] = {%uU",sbx_tab[0]);
  for (i = 1; i < 256; i++) {
    fprintf(tabf,",%uU",sbx_tab[i]);
  }
  fprintf(tabf,"};\n");

  fprintf(tabf,"u1byte isb_tab[] = {%uU",isb_tab[0]);
  for (i = 1; i < 256; i++) {
    fprintf(tabf,",%uU",isb_tab[i]);
  }
  fprintf(tabf,"};\n");

  fprintf(tabf,"u4byte rco_tab[] = {%uU",rco_tab[0]);
  for (i = 1; i < 10; i++) {
    fprintf(tabf,",%uU",rco_tab[i]);
  }
  fprintf(tabf,"};\n");

  fprintf(tabf,"u4byte ft_tab[][256] = {");
  for (i = 0; i < 4; i++) {
    if (i) fprintf(tabf,",");
    fprintf(tabf,"\n{ %uU",ft_tab[i][0]);
    for (j = 1; j < 256; j++) {
      fprintf(tabf,",%uU",ft_tab[i][j]);
    }
    fprintf(tabf,"}");
  }
  fprintf(tabf,"};\n");

  fprintf(tabf,"u4byte it_tab[][256] = {");
  for (i = 0; i < 4; i++) {
    if (i) fprintf(tabf,",");
    fprintf(tabf,"\n{ %uU",it_tab[i][0]);
    for (j = 1; j < 256; j++) {
      fprintf(tabf,",%uU",it_tab[i][j]);
    }
    fprintf(tabf,"}");
  }
  fprintf(tabf,"};\n");

  fprintf(tabf,"u4byte fl_tab[][256] = {");
  for (i = 0; i < 4; i++) {
    if (i) fprintf(tabf,",");
    fprintf(tabf,"\n{ %uU",fl_tab[i][0]);
    for (j = 1; j < 256; j++) {
      fprintf(tabf,",%uU",fl_tab[i][j]);
    }
    fprintf(tabf,"}");
  }
  fprintf(tabf,"};\n");

  fprintf(tabf,"u4byte il_tab[][256] = {");
  for (i = 0; i < 4; i++) {
    if (i) fprintf(tabf,",");
    fprintf(tabf,"\n{ %uU",il_tab[i][0]);
    for (j = 1; j < 256; j++) {
      fprintf(tabf,",%uU",il_tab[i][j]);
    }
    fprintf(tabf,"}");
  }
  fprintf(tabf,"};\n\n");

  fclose(tabf);
}

#else

#define star_x(x) (((x) & 0x7f7f7f7f) << 1) ^ ((((x) & 0x80808080) >> 7) * 0x1b)

#define imix_col(y,x)       \
    u   = star_x(x);        \
    v   = star_x(u);        \
    w   = star_x(v);        \
    t   = w ^ (x);          \
   (y)  = u ^ v ^ w;        \
   (y) ^= rotr(u ^ t,  8) ^ \
          rotr(v ^ t, 16) ^ \
          rotr(t,24)

/* initialise the key schedule from the user supplied key   */

#define loop4(i)                                    \
{   t = ls_box(rotr(t,  8)) ^ rco_tab[i];           \
    t ^= e_key[4 * i];     e_key[4 * i + 4] = t;    \
    t ^= e_key[4 * i + 1]; e_key[4 * i + 5] = t;    \
    t ^= e_key[4 * i + 2]; e_key[4 * i + 6] = t;    \
    t ^= e_key[4 * i + 3]; e_key[4 * i + 7] = t;    \
}

#define loop6(i)                                    \
{   t = ls_box(rotr(t,  8)) ^ rco_tab[i];           \
    t ^= e_key[6 * i];     e_key[6 * i + 6] = t;    \
    t ^= e_key[6 * i + 1]; e_key[6 * i + 7] = t;    \
    t ^= e_key[6 * i + 2]; e_key[6 * i + 8] = t;    \
    t ^= e_key[6 * i + 3]; e_key[6 * i + 9] = t;    \
    t ^= e_key[6 * i + 4]; e_key[6 * i + 10] = t;   \
    t ^= e_key[6 * i + 5]; e_key[6 * i + 11] = t;   \
}

#define loop8(i)                                    \
{   t = ls_box(rotr(t,  8)) ^ rco_tab[i];           \
    t ^= e_key[8 * i];     e_key[8 * i + 8] = t;    \
    t ^= e_key[8 * i + 1]; e_key[8 * i + 9] = t;    \
    t ^= e_key[8 * i + 2]; e_key[8 * i + 10] = t;   \
    t ^= e_key[8 * i + 3]; e_key[8 * i + 11] = t;   \
    t  = e_key[8 * i + 4] ^ ls_box(t);              \
    e_key[8 * i + 12] = t;                          \
    t ^= e_key[8 * i + 5]; e_key[8 * i + 13] = t;   \
    t ^= e_key[8 * i + 6]; e_key[8 * i + 14] = t;   \
    t ^= e_key[8 * i + 7]; e_key[8 * i + 15] = t;   \
}

u4byte *rijndael_set_key(const u4byte in_key[], const u4byte key_len, 
			 u4byte e_key[], u4byte d_key[], u4byte *k_len)
{   
  u4byte  i, t, u, v, w;

  *k_len = (key_len + 31) / 32;

  e_key[0] = in_key[0]; e_key[1] = in_key[1];
  e_key[2] = in_key[2]; e_key[3] = in_key[3];

  switch(*k_len)
    {
    case 4: t = e_key[3];
      for(i = 0; i < 10; ++i) 
	loop4(i);
      break;

    case 6: e_key[4] = in_key[4]; t = e_key[5] = in_key[5];
      for(i = 0; i < 8; ++i) 
	loop6(i);
      break;

    case 8: e_key[4] = in_key[4]; e_key[5] = in_key[5];
      e_key[6] = in_key[6]; t = e_key[7] = in_key[7];
      for(i = 0; i < 7; ++i) 
	loop8(i);
      break;
    }

  d_key[0] = e_key[0]; d_key[1] = e_key[1];
  d_key[2] = e_key[2]; d_key[3] = e_key[3];

  for(i = 4; i < 4 * *k_len + 24; ++i)
    {
      imix_col(d_key[i], e_key[i]);
    }

  return e_key;
};

/* encrypt a block of text  */

#define f_nround(bo, bi, k) \
    f_rn(bo, bi, 0, k);     \
    f_rn(bo, bi, 1, k);     \
    f_rn(bo, bi, 2, k);     \
    f_rn(bo, bi, 3, k);     \
    k += 4

#define f_lround(bo, bi, k) \
    f_rl(bo, bi, 0, k);     \
    f_rl(bo, bi, 1, k);     \
    f_rl(bo, bi, 2, k);     \
    f_rl(bo, bi, 3, k)

void rijndael_encrypt(const u4byte in_blk[4], u4byte out_blk[4],
		      const u4byte e_key[], u4byte k_len)
{  
  u4byte  b0[4], b1[4];
  const u4byte *kp;
  
  b0[0] = in_blk[0] ^ e_key[0]; b0[1] = in_blk[1] ^ e_key[1];
  b0[2] = in_blk[2] ^ e_key[2]; b0[3] = in_blk[3] ^ e_key[3];

  kp = e_key + 4;

  if(k_len > 6)
    {
      f_nround(b1, b0, kp); f_nround(b0, b1, kp);
    }

  if(k_len > 4)
    {
      f_nround(b1, b0, kp); f_nround(b0, b1, kp);
    }

  f_nround(b1, b0, kp); f_nround(b0, b1, kp);
  f_nround(b1, b0, kp); f_nround(b0, b1, kp);
  f_nround(b1, b0, kp); f_nround(b0, b1, kp);
  f_nround(b1, b0, kp); f_nround(b0, b1, kp);
  f_nround(b1, b0, kp); f_lround(b0, b1, kp);

  out_blk[0] = b0[0]; out_blk[1] = b0[1];
  out_blk[2] = b0[2]; out_blk[3] = b0[3];
};

/* decrypt a block of text  */

#define i_nround(bo, bi, k) \
    i_rn(bo, bi, 0, k);     \
    i_rn(bo, bi, 1, k);     \
    i_rn(bo, bi, 2, k);     \
    i_rn(bo, bi, 3, k);     \
    k -= 4

#define i_lround(bo, bi, k) \
    i_rl(bo, bi, 0, k);     \
    i_rl(bo, bi, 1, k);     \
    i_rl(bo, bi, 2, k);     \
    i_rl(bo, bi, 3, k)

void rijndael_decrypt(const u4byte in_blk[4], u4byte out_blk[4],
		      const u4byte e_key[], const u4byte d_key[], u4byte k_len)
{   
  u4byte  b0[4], b1[4];
  const u4byte *kp;

  b0[0] = in_blk[0] ^ e_key[4 * k_len + 24]; b0[1] = in_blk[1] ^ e_key[4 * k_len + 25];
  b0[2] = in_blk[2] ^ e_key[4 * k_len + 26]; b0[3] = in_blk[3] ^ e_key[4 * k_len + 27];

  kp = d_key + 4 * (k_len + 5);

  if(k_len > 6)
    {
      i_nround(b1, b0, kp); i_nround(b0, b1, kp);
    }

  if(k_len > 4)
    {
      i_nround(b1, b0, kp); i_nround(b0, b1, kp);
    }

  i_nround(b1, b0, kp); i_nround(b0, b1, kp);
  i_nround(b1, b0, kp); i_nround(b0, b1, kp);
  i_nround(b1, b0, kp); i_nround(b0, b1, kp);
  i_nround(b1, b0, kp); i_nround(b0, b1, kp);
  i_nround(b1, b0, kp); i_lround(b0, b1, kp);

  out_blk[0] = b0[0]; out_blk[1] = b0[1];
  out_blk[2] = b0[2]; out_blk[3] = b0[3];
};

#endif