/* This is an independent implementation of the encryption algorithm:   */
/*                                                                      */
/*         RIJNDAEL by Joan Daemen and Vincent Rijmen                   */
/*                                                                      */
/* which is a candidate algorithm in the Advanced Encryption Standard   */
/* programme of the US National Institute of Standards and Technology.  */
/*                                                                      */
/* Copyright in this implementation is held by Dr B R Gladman but I     */
/* hereby give permission for its free direct or derivative use subject */
/* to acknowledgment of its origin and compliance with any conditions   */
/* that the originators of the algorithm place on its exploitation.     */
/*                                                                      */
/* Dr Brian Gladman (gladman@seven77.demon.co.uk) 14th January 1999     */

#include <mix/aes.h>

#define LARGE_TABLES

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];

#ifdef  LARGE_TABLES
u4byte fl_tab[4][256];
u4byte il_tab[4][256];

#endif

u4byte tab_gen = 0;

u4byte k_len2;
u4byte e_key[60];
u4byte d_key[60];

#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)

#ifdef LARGE_TABLES

#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)

#else

#define ls_box(x)                            \
    ((u4byte)sbx_tab[byte(x, 0)] <<  0) ^    \
    ((u4byte)sbx_tab[byte(x, 1)] <<  8) ^    \
    ((u4byte)sbx_tab[byte(x, 2)] << 16) ^    \
    ((u4byte)sbx_tab[byte(x, 3)] << 24)

#define f_rl(bo, bi, n, k)                                      \
    bo[n] = (u4byte)sbx_tab[byte(bi[n],0)] ^                    \
        rotl(((u4byte)sbx_tab[byte(bi[(n + 1) & 3],1)]),  8) ^  \
        rotl(((u4byte)sbx_tab[byte(bi[(n + 2) & 3],2)]), 16) ^  \
        rotl(((u4byte)sbx_tab[byte(bi[(n + 3) & 3],3)]), 24) ^ *(k + n)

#define i_rl(bo, bi, n, k)                                      \
    bo[n] = (u4byte)isb_tab[byte(bi[n],0)] ^                    \
        rotl(((u4byte)isb_tab[byte(bi[(n + 3) & 3],1)]),  8) ^  \
        rotl(((u4byte)isb_tab[byte(bi[(n + 2) & 3],2)]), 16) ^  \
        rotl(((u4byte)isb_tab[byte(bi[(n + 1) & 3],3)]), 24) ^ *(k + n)

#endif

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];

#ifdef  LARGE_TABLES

      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);
#endif
      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];

#ifdef  LARGE_TABLES

      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);
#endif
      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);
    }

  tab_gen = 1;
};

#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_setkey(const u4byte in_key[], const u4byte key_len)
{
  u4byte i, t, u, v, w;

  if (!tab_gen)

    gen_tabs();

  k_len2 = (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_len2)
    {
    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_len2 + 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])
{
  u4byte b0[4], b1[4], *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_len2 > 6)
    {
      f_nround(b1, b0, kp);
      f_nround(b0, b1, kp);
    }

  if (k_len2 > 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])
{
  u4byte b0[4], b1[4], *kp;

  b0[0] = in_blk[0] ^ e_key[4 * k_len2 + 24];
  b0[1] = in_blk[1] ^ e_key[4 * k_len2 + 25];
  b0[2] = in_blk[2] ^ e_key[4 * k_len2 + 26];
  b0[3] = in_blk[3] ^ e_key[4 * k_len2 + 27];

  kp = d_key + 4 * (k_len2 + 5);

  if (k_len2 > 6)
    {
      i_nround(b1, b0, kp);
      i_nround(b0, b1, kp);
    }

  if (k_len2 > 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];
};
