/* Modified for SILC. -Pekka */
/* The AES */

/* 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     */

/* Timing data for Rijndael (rijndael.c)

Algorithm: rijndael (rijndael.c)

128 bit key:
Key Setup:    305/1389 cycles (encrypt/decrypt)
Encrypt:       374 cycles =    68.4 mbits/sec
Decrypt:       352 cycles =    72.7 mbits/sec
Mean:          363 cycles =    70.5 mbits/sec

192 bit key:
Key Setup:    277/1595 cycles (encrypt/decrypt)
Encrypt:       439 cycles =    58.3 mbits/sec
Decrypt:       425 cycles =    60.2 mbits/sec
Mean:          432 cycles =    59.3 mbits/sec

256 bit key:
Key Setup:    374/1960 cycles (encrypt/decrypt)
Encrypt:       502 cycles =    51.0 mbits/sec
Decrypt:       498 cycles =    51.4 mbits/sec
Mean:          500 cycles =    51.2 mbits/sec

*/

#include "silcincludes.h"
#include "rijndael_internal.h"
#include "aes.h"

/* 
 * SILC Crypto API for Rijndael
 */

/* Sets the key for the cipher. */

SILC_CIPHER_API_SET_KEY(aes)
{
  uint32 k[8];

  SILC_GET_WORD_KEY(key, k, keylen);
  rijndael_set_key((RijndaelContext *)context, k, keylen);

  return TRUE;
}

/* Sets the string as a new key for the cipher. The string is first
   hashed and then used as a new key. */

SILC_CIPHER_API_SET_KEY_WITH_STRING(aes)
{
  /*  unsigned char key[md5_hash_len];
  SilcMarsContext *ctx = (SilcMarsContext *)context;

  make_md5_hash(string, &key);
  memcpy(&ctx->key, mars_set_key(&key, keylen), keylen);
  memset(&key, 'F', sizeoof(key));
  */

  return 1;
}

/* Returns the size of the cipher context. */

SILC_CIPHER_API_CONTEXT_LEN(aes)
{
  return sizeof(RijndaelContext);
}

/* Encrypts with the cipher in CBC mode. Source and destination buffers
   maybe one and same. */

SILC_CIPHER_API_ENCRYPT_CBC(aes)
{
  uint32 tiv[4];
  int i;

  SILC_CBC_GET_IV(tiv, iv);

  SILC_CBC_ENC_PRE(tiv, src);
  rijndael_encrypt((RijndaelContext *)context, tiv, tiv);
  SILC_CBC_ENC_POST(tiv, dst, src);

  for (i = 16; i < len; i += 16) {
    SILC_CBC_ENC_PRE(tiv, src);
    rijndael_encrypt((RijndaelContext *)context, tiv, tiv);
    SILC_CBC_ENC_POST(tiv, dst, src);
  }

  SILC_CBC_PUT_IV(tiv, iv);

  return TRUE;
}

/* Decrypts with the cipher in CBC mode. Source and destination buffers
   maybe one and same. */

SILC_CIPHER_API_DECRYPT_CBC(aes)
{
  uint32 tmp[4], tmp2[4], tiv[4];
  int i;

  SILC_CBC_GET_IV(tiv, iv);

  SILC_CBC_DEC_PRE(tmp, src);
  rijndael_decrypt((RijndaelContext *)context, tmp, tmp2);
  SILC_CBC_DEC_POST(tmp2, dst, src, tmp, tiv);

  for (i = 16; i < len; i += 16) {
    SILC_CBC_DEC_PRE(tmp, src);
    rijndael_decrypt((RijndaelContext *)context, tmp, tmp2); 
    SILC_CBC_DEC_POST(tmp2, dst, src, tmp, tiv);
  }
  
  SILC_CBC_PUT_IV(tiv, iv);
  
  return TRUE;
}

#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];

u4byte  fl_tab[4][256];
u4byte  il_tab[4][256];

u4byte  tab_gen = 0;

#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_set_key(RijndaelContext *ctx,
			 const u4byte in_key[], const u4byte key_len)
{   
    u4byte  i, t, u, v, w;
    u4byte *e_key = ctx->e_key;
    u4byte *d_key = ctx->d_key;
    u4byte k_len;

    if(!tab_gen)
        gen_tabs();

    k_len = ctx->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(RijndaelContext *ctx,
		      const u4byte in_blk[4], u4byte out_blk[4])
{   
    u4byte  b0[4], b1[4], *kp;
    u4byte *e_key = ctx->e_key;
    u4byte k_len = ctx->k_len;

    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(RijndaelContext *ctx,
		      const u4byte in_blk[4], u4byte out_blk[4])
{   
    u4byte  b0[4], b1[4], *kp;
    u4byte *e_key = ctx->e_key;
    u4byte *d_key = ctx->d_key;
    u4byte k_len = ctx->k_len;

    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];
};
