/* Modified for SILC. -Pekka */

/* This is an independent implementation of the encryption algorithm:   */
/*                                                                      */
/*         MARS by a team at IBM,                                        */
/*                                                                      */
/* 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. The MARS */
/* algorithm is covered by a pending patent application owned by IBM,   */
/* who intend to offer a royalty free license under any issued patent   */
/* that results from such application if MARS is selected as the AES    */
/* algorithm.  In the interim, you may evaluate the MARS algorithm for  */
/* your personal, lawful, non-profit purposes as an end user.           */
/*                                                                      */
/* The header above modified on June 6th 1999.                          */
/* Dr Brian Gladman (gladman@seven77.demon.co.uk) 14th January 1999     */

/* Timing data for MARS (mars.c)

128 bit key:
Key Setup:    4316 cycles
Encrypt:       369 cycles =    69.4 mbits/sec
Decrypt:       376 cycles =    68.1 mbits/sec
Mean:          373 cycles =    68.7 mbits/sec

192 bit key:
Key Setup:    4377 cycles
Encrypt:       373 cycles =    68.6 mbits/sec
Decrypt:       379 cycles =    67.5 mbits/sec
Mean:          376 cycles =    68.1 mbits/sec

256 bit key:
Key Setup:    4340 cycles
Encrypt:       369 cycles =    69.4 mbits/sec
Decrypt:       376 cycles =    68.1 mbits/sec
Mean:          373 cycles =    68.7 mbits/sec

*/

#include "silcincludes.h"
#include "mars_internal.h"
#include "mars.h"

/* 
 * SILC Crypto API for MARS 
 */

/* Sets the key for cipher MARS. */

SILC_CIPHER_API_SET_KEY(mars)
{
  SilcUInt32 k[8];

  SILC_GET_WORD_KEY(key, k, keylen);
  mars_set_key((MarsContext *)context, k, keylen);

  return TRUE;
}

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

SILC_CIPHER_API_SET_KEY_WITH_STRING(mars)
{
  /*  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 TRUE;
}

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

SILC_CIPHER_API_CONTEXT_LEN(mars)
{
  return sizeof(MarsContext);
}

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

SILC_CIPHER_API_ENCRYPT_CBC(mars)
{
  SilcUInt32 tiv[4];
  int i;

  SILC_CBC_GET_IV(tiv, iv);

  SILC_CBC_ENC_PRE(tiv, src);
  mars_encrypt((MarsContext *)context, tiv, tiv);
  SILC_CBC_ENC_POST(tiv, dst, src);

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

  SILC_CBC_PUT_IV(tiv, iv);

  return TRUE;
}

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

SILC_CIPHER_API_DECRYPT_CBC(mars)
{
  SilcUInt32 tmp[4], tmp2[4], tiv[4];
  int i;

  SILC_CBC_GET_IV(tiv, iv);

  SILC_CBC_DEC_PRE(tmp, src);
  mars_decrypt((MarsContext *)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);
    mars_decrypt((MarsContext *)context, tmp, tmp2);
    SILC_CBC_DEC_POST(tmp2, dst, src, tmp, tiv);
  }

  SILC_CBC_PUT_IV(tiv, iv);

  return TRUE;
}

static u4byte s_box[] = 
{
    0x09d0c479, 0x28c8ffe0, 0x84aa6c39, 0x9dad7287, /* 0x000    */
    0x7dff9be3, 0xd4268361, 0xc96da1d4, 0x7974cc93, 
    0x85d0582e, 0x2a4b5705, 0x1ca16a62, 0xc3bd279d, 
    0x0f1f25e5, 0x5160372f, 0xc695c1fb, 0x4d7ff1e4, 
    0xae5f6bf4, 0x0d72ee46, 0xff23de8a, 0xb1cf8e83, /* 0x010    */
    0xf14902e2, 0x3e981e42, 0x8bf53eb6, 0x7f4bf8ac, 
    0x83631f83, 0x25970205, 0x76afe784, 0x3a7931d4, 
    0x4f846450, 0x5c64c3f6, 0x210a5f18, 0xc6986a26, 
    0x28f4e826, 0x3a60a81c, 0xd340a664, 0x7ea820c4, /* 0x020    */
    0x526687c5, 0x7eddd12b, 0x32a11d1d, 0x9c9ef086, 
    0x80f6e831, 0xab6f04ad, 0x56fb9b53, 0x8b2e095c, 
    0xb68556ae, 0xd2250b0d, 0x294a7721, 0xe21fb253, 
    0xae136749, 0xe82aae86, 0x93365104, 0x99404a66, /* 0x030    */
    0x78a784dc, 0xb69ba84b, 0x04046793, 0x23db5c1e, 
    0x46cae1d6, 0x2fe28134, 0x5a223942, 0x1863cd5b, 
    0xc190c6e3, 0x07dfb846, 0x6eb88816, 0x2d0dcc4a, 
    0xa4ccae59, 0x3798670d, 0xcbfa9493, 0x4f481d45, /* 0x040    */
    0xeafc8ca8, 0xdb1129d6, 0xb0449e20, 0x0f5407fb, 
    0x6167d9a8, 0xd1f45763, 0x4daa96c3, 0x3bec5958, 
    0xababa014, 0xb6ccd201, 0x38d6279f, 0x02682215, 
    0x8f376cd5, 0x092c237e, 0xbfc56593, 0x32889d2c, /* 0x050    */
    0x854b3e95, 0x05bb9b43, 0x7dcd5dcd, 0xa02e926c, 
    0xfae527e5, 0x36a1c330, 0x3412e1ae, 0xf257f462, 
    0x3c4f1d71, 0x30a2e809, 0x68e5f551, 0x9c61ba44, 
    0x5ded0ab8, 0x75ce09c8, 0x9654f93e, 0x698c0cca, /* 0x060    */
    0x243cb3e4, 0x2b062b97, 0x0f3b8d9e, 0x00e050df, 
    0xfc5d6166, 0xe35f9288, 0xc079550d, 0x0591aee8, 
    0x8e531e74, 0x75fe3578, 0x2f6d829a, 0xf60b21ae, 
    0x95e8eb8d, 0x6699486b, 0x901d7d9b, 0xfd6d6e31, /* 0x070    */ 
    0x1090acef, 0xe0670dd8, 0xdab2e692, 0xcd6d4365, 
    0xe5393514, 0x3af345f0, 0x6241fc4d, 0x460da3a3, 
    0x7bcf3729, 0x8bf1d1e0, 0x14aac070, 0x1587ed55, 
    0x3afd7d3e, 0xd2f29e01, 0x29a9d1f6, 0xefb10c53, /* 0x080    */
    0xcf3b870f, 0xb414935c, 0x664465ed, 0x024acac7, 
    0x59a744c1, 0x1d2936a7, 0xdc580aa6, 0xcf574ca8, 
    0x040a7a10, 0x6cd81807, 0x8a98be4c, 0xaccea063, 
    0xc33e92b5, 0xd1e0e03d, 0xb322517e, 0x2092bd13, /* 0x090    */
    0x386b2c4a, 0x52e8dd58, 0x58656dfb, 0x50820371, 
    0x41811896, 0xe337ef7e, 0xd39fb119, 0xc97f0df6, 
    0x68fea01b, 0xa150a6e5, 0x55258962, 0xeb6ff41b, 
    0xd7c9cd7a, 0xa619cd9e, 0xbcf09576, 0x2672c073, /* 0x0a0    */
    0xf003fb3c, 0x4ab7a50b, 0x1484126a, 0x487ba9b1, 
    0xa64fc9c6, 0xf6957d49, 0x38b06a75, 0xdd805fcd, 
    0x63d094cf, 0xf51c999e, 0x1aa4d343, 0xb8495294, 
    0xce9f8e99, 0xbffcd770, 0xc7c275cc, 0x378453a7, /* 0x0b0    */
    0x7b21be33, 0x397f41bd, 0x4e94d131, 0x92cc1f98, 
    0x5915ea51, 0x99f861b7, 0xc9980a88, 0x1d74fd5f, 
    0xb0a495f8, 0x614deed0, 0xb5778eea, 0x5941792d, 
    0xfa90c1f8, 0x33f824b4, 0xc4965372, 0x3ff6d550, /* 0x0c0    */
    0x4ca5fec0, 0x8630e964, 0x5b3fbbd6, 0x7da26a48,
    0xb203231a, 0x04297514, 0x2d639306, 0x2eb13149, 
    0x16a45272, 0x532459a0, 0x8e5f4872, 0xf966c7d9, 
    0x07128dc0, 0x0d44db62, 0xafc8d52d, 0x06316131, /* 0x0d0    */ 
    0xd838e7ce, 0x1bc41d00, 0x3a2e8c0f, 0xea83837e,
    0xb984737d, 0x13ba4891, 0xc4f8b949, 0xa6d6acb3, 
    0xa215cdce, 0x8359838b, 0x6bd1aa31, 0xf579dd52, 
    0x21b93f93, 0xf5176781, 0x187dfdde, 0xe94aeb76, /* 0x0e0    */ 
    0x2b38fd54, 0x431de1da, 0xab394825, 0x9ad3048f,
    0xdfea32aa, 0x659473e3, 0x623f7863, 0xf3346c59, 
    0xab3ab685, 0x3346a90b, 0x6b56443e, 0xc6de01f8, 
    0x8d421fc0, 0x9b0ed10c, 0x88f1a1e9, 0x54c1f029, /* 0x0f0    */ 
    0x7dead57b, 0x8d7ba426, 0x4cf5178a, 0x551a7cca, 
    0x1a9a5f08, 0xfcd651b9, 0x25605182, 0xe11fc6c3, 
    0xb6fd9676, 0x337b3027, 0xb7c8eb14, 0x9e5fd030,

    0x6b57e354, 0xad913cf7, 0x7e16688d, 0x58872a69, /* 0x100    */
    0x2c2fc7df, 0xe389ccc6, 0x30738df1, 0x0824a734, 
    0xe1797a8b, 0xa4a8d57b, 0x5b5d193b, 0xc8a8309b, 
    0x73f9a978, 0x73398d32, 0x0f59573e, 0xe9df2b03, 
    0xe8a5b6c8, 0x848d0704, 0x98df93c2, 0x720a1dc3, /* 0x110    */ 
    0x684f259a, 0x943ba848, 0xa6370152, 0x863b5ea3, 
    0xd17b978b, 0x6d9b58ef, 0x0a700dd4, 0xa73d36bf, 
    0x8e6a0829, 0x8695bc14, 0xe35b3447, 0x933ac568, 
    0x8894b022, 0x2f511c27, 0xddfbcc3c, 0x006662b6, /* 0x120    */
    0x117c83fe, 0x4e12b414, 0xc2bca766, 0x3a2fec10, 
    0xf4562420, 0x55792e2a, 0x46f5d857, 0xceda25ce, 
    0xc3601d3b, 0x6c00ab46, 0xefac9c28, 0xb3c35047, 
    0x611dfee3, 0x257c3207, 0xfdd58482, 0x3b14d84f, /* 0x130    */
    0x23becb64, 0xa075f3a3, 0x088f8ead, 0x07adf158, 
    0x7796943c, 0xfacabf3d, 0xc09730cd, 0xf7679969, 
    0xda44e9ed, 0x2c854c12, 0x35935fa3, 0x2f057d9f, 
    0x690624f8, 0x1cb0bafd, 0x7b0dbdc6, 0x810f23bb, /* 0x140    */
    0xfa929a1a, 0x6d969a17, 0x6742979b, 0x74ac7d05, 
    0x010e65c4, 0x86a3d963, 0xf907b5a0, 0xd0042bd3, 
    0x158d7d03, 0x287a8255, 0xbba8366f, 0x096edc33, 
    0x21916a7b, 0x77b56b86, 0x951622f9, 0xa6c5e650, /* 0x150    */
    0x8cea17d1, 0xcd8c62bc, 0xa3d63433, 0x358a68fd, 
    0x0f9b9d3c, 0xd6aa295b, 0xfe33384a, 0xc000738e, 
    0xcd67eb2f, 0xe2eb6dc2, 0x97338b02, 0x06c9f246, 
    0x419cf1ad, 0x2b83c045, 0x3723f18a, 0xcb5b3089, /* 0x160    */
    0x160bead7, 0x5d494656, 0x35f8a74b, 0x1e4e6c9e, 
    0x000399bd, 0x67466880, 0xb4174831, 0xacf423b2, 
    0xca815ab3, 0x5a6395e7, 0x302a67c5, 0x8bdb446b, 
    0x108f8fa4, 0x10223eda, 0x92b8b48b, 0x7f38d0ee, /* 0x170    */
    0xab2701d4, 0x0262d415, 0xaf224a30, 0xb3d88aba, 
    0xf8b2c3af, 0xdaf7ef70, 0xcc97d3b7, 0xe9614b6c, 
    0x2baebff4, 0x70f687cf, 0x386c9156, 0xce092ee5, 
    0x01e87da6, 0x6ce91e6a, 0xbb7bcc84, 0xc7922c20, /* 0x180    */
    0x9d3b71fd, 0x060e41c6, 0xd7590f15, 0x4e03bb47, 
    0x183c198e, 0x63eeb240, 0x2ddbf49a, 0x6d5cba54, 
    0x923750af, 0xf9e14236, 0x7838162b, 0x59726c72, 
    0x81b66760, 0xbb2926c1, 0x48a0ce0d, 0xa6c0496d, /* 0x190    */
    0xad43507b, 0x718d496a, 0x9df057af, 0x44b1bde6, 
    0x054356dc, 0xde7ced35, 0xd51a138b, 0x62088cc9, 
    0x35830311, 0xc96efca2, 0x686f86ec, 0x8e77cb68, 
    0x63e1d6b8, 0xc80f9778, 0x79c491fd, 0x1b4c67f2, /* 0x1a0    */
    0x72698d7d, 0x5e368c31, 0xf7d95e2e, 0xa1d3493f,
    0xdcd9433e, 0x896f1552, 0x4bc4ca7a, 0xa6d1baf4, 
    0xa5a96dcc, 0x0bef8b46, 0xa169fda7, 0x74df40b7, 
    0x4e208804, 0x9a756607, 0x038e87c8, 0x20211e44, /* 0x1b0    */ 
    0x8b7ad4bf, 0xc6403f35, 0x1848e36d, 0x80bdb038, 
    0x1e62891c, 0x643d2107, 0xbf04d6f8, 0x21092c8c, 
    0xf644f389, 0x0778404e, 0x7b78adb8, 0xa2c52d53, 
    0x42157abe, 0xa2253e2e, 0x7bf3f4ae, 0x80f594f9, /* 0x1c0    */
    0x953194e7, 0x77eb92ed, 0xb3816930, 0xda8d9336, 
    0xbf447469, 0xf26d9483, 0xee6faed5, 0x71371235, 
    0xde425f73, 0xb4e59f43, 0x7dbe2d4e, 0x2d37b185, 
    0x49dc9a63, 0x98c39d98, 0x1301c9a2, 0x389b1bbf, /* 0x1d0    */
    0x0c18588d, 0xa421c1ba, 0x7aa3865c, 0x71e08558, 
    0x3c5cfcaa, 0x7d239ca4, 0x0297d9dd, 0xd7dc2830, 
    0x4b37802b, 0x7428ab54, 0xaeee0347, 0x4b3fbb85, 
    0x692f2f08, 0x134e578e, 0x36d9e0bf, 0xae8b5fcf, /* 0x1e0    */
    0xedb93ecf, 0x2b27248e, 0x170eb1ef, 0x7dc57fd6, 
    0x1e760f16, 0xb1136601, 0x864e1b9b, 0xd7ea7319, 
    0x3ab871bd, 0xcfa4d76f, 0xe31bd782, 0x0dbeb469, 
    0xabb96061, 0x5370f85d, 0xffb07e37, 0xda30d0fb, /* 0x1f0    */
    0xebc977b6, 0x0b98b40f, 0x3a4d0fe6, 0xdf4fc26b, 
    0x159cf22a, 0xc298d6e2, 0x2b78ef6a, 0x61a94ac0, 
    0xab561187, 0x14eea0f0, 0xdf0d4164, 0x19af70ee
};

static u4byte vk[47] =
{ 
    0x09d0c479, 0x28c8ffe0, 0x84aa6c39, 0x9dad7287, 0x7dff9be3, 0xd4268361,
    0xc96da1d4
};

#define f_mix(a,b,c,d)                  \
        r = rotr(a, 8);                 \
        b ^= s_box[a & 255];            \
        b += s_box[(r & 255) + 256];    \
        r = rotr(a, 16);                \
        a  = rotr(a, 24);               \
        c += s_box[r & 255];            \
        d ^= s_box[(a & 255) + 256]

#define b_mix(a,b,c,d)                  \
        r = rotl(a, 8);                 \
        b ^= s_box[(a & 255) + 256];    \
        c -= s_box[r & 255];            \
        r = rotl(a, 16);                \
        a  = rotl(a, 24);               \
        d -= s_box[(r & 255) + 256];    \
        d ^= s_box[a & 255]

#define f_ktr(a,b,c,d,i)    \
    m = a + l_key[i];  \
    a = rotl(a, 13);        \
    r = a * l_key[i + 1];   \
    l = s_box[m & 511];     \
    r = rotl(r, 5);         \
    c += rotl(m, r);        \
    l ^= r;                 \
    r = rotl(r, 5);         \
    l ^= r;                 \
    d ^= r;                 \
    b += rotl(l, r)

#define r_ktr(a,b,c,d,i)    \
    r = a * l_key[i + 1];   \
    a = rotr(a, 13);        \
    m = a + l_key[i];  \
    l = s_box[m & 511];     \
    r = rotl(r, 5);         \
    l ^= r;                 \
    c -= rotl(m, r);        \
    r = rotl(r, 5);         \
    l ^= r;                 \
    d ^= r;                 \
    b -= rotl(l, r)

/* For a 32 bit word (x) generate a mask (m) such that a bit in */
/* m is set to 1 if and only if the corresponding bit in x is:  */
/*                                                              */
/* 1. in a sequence of 10 or more adjacent '0' bits             */
/* 2. in a sequence of 10 or more adjacent '1' bits             */
/* 3. but is not either endpoint of such a sequence unless such */
/*    an endpoint is at the top bit (bit 31) of a word and is   */
/*    in a sequence of '0' bits.                                */
/*                                                              */
/* The only situation in which a sequence endpoint is included  */
/* in the mask is hence when the endpoint is at bit 31 and is   */
/* the endpoint of a sequence of '0' bits. My thanks go to Shai */
/* Halevi of IBM for the neat trick (which I missed) of finding */
/* the '0' and '1' sequences at the same time.                  */

u4byte gen_mask(u4byte x)
{   u4byte  m;

    /* if m{bn} stands for bit number bn of m, set m{bn} = 1 if */
    /* x{bn} == x{bn+1} for 0 <= bn <= 30.  That is, set a bit  */
    /* in m if the corresponding bit and the next higher bit in */
    /* x are equal in value (set m{31} = 0).                    */

    m = (~x ^ (x >> 1)) & 0x7fffffff;

    /* Sequences of 9 '1' bits in m now correspond to sequences */
    /* of 10 '0's or 10 '1' bits in x.  Shift and 'and' bits in */
    /* m to find sequences of 9 or more '1' bits.   As a result */
    /* bits in m are set if they are at the bottom of sequences */
    /* of 10 adjacent '0's or 10 adjacent '1's in x.            */

    m &= (m >> 1) & (m >> 2); m &= (m >> 3) & (m >> 6); 
    
    if(!m)  /* return if mask is empty - no key fixing needed   */
            /* is this early return worthwhile?                 */
        return 0;
    
    /* We need the internal bits in each continuous sequence of */
    /* matching bits (that is the bits less the two endpoints). */
    /* We thus propagate each set bit into the 8 internal bits  */
    /* that it represents, starting 1 left and finsihing 8 left */
    /* of its position.                                         */

    m <<= 1; m |= (m << 1); m |= (m << 2); m |= (m << 4);

    /* m is now correct except for the odd behaviour of bit 31, */
    /* that is, it will be set if it is in a sequence of 10 or  */
    /* more '0's and clear otherwise.                           */

    m |= (m << 1) & ~x & 0x80000000;

    return m & 0xfffffffc;
};

/* My thanks to Louis Granboulan for spotting an error in the   */
/* previous version of set_key.                                 */

u4byte *mars_set_key(MarsContext *ctx,
		     const u4byte in_key[], const u4byte key_len)
{   
    u4byte  i, j, m, w; 
    u4byte *l_key = ctx->l_key;
 
    m = key_len / 32 - 1;

    for(i = j = 0; i < 39; ++i)
    {
      vk[i + 7] = rotl(vk[i] ^ vk[i + 5], 3) ^ in_key[j] ^ i;

      j = (j == m ? 0 : j + 1);
    }

    vk[46] = key_len / 32;

    for(j = 0; j < 7; ++j)
    {
         for(i = 1; i < 40; ++i)
         
            vk[i + 7] = rotl(vk[i + 7] + s_box[vk[i + 6] & 511], 9);

        vk[7] = rotl(vk[7] + s_box[vk[46] & 511], 9);
    }

    for(i = j = 0; i < 40; ++i)
    {
        l_key[j] = vk[i + 7];

        j = (j < 33 ? j + 7 : j - 33);
    }

    for(i = 5; i < 37; i += 2)
    {
        w = l_key[i] | 3; 

        if((m = gen_mask(w)))
        
            w ^= (rotl(s_box[265 + (l_key[i] & 3)], l_key[i + 3] & 31) & m);

        l_key[i] = w;
    }

    return l_key;
};

void mars_encrypt(MarsContext *ctx,
		  const u4byte in_blk[4], u4byte out_blk[4])
{   
    u4byte  a, b, c, d, l, m, r;
    u4byte *l_key = ctx->l_key;

    a = in_blk[0] + l_key[0]; b = in_blk[1] + l_key[1];
    c = in_blk[2] + l_key[2]; d = in_blk[3] + l_key[3];

    f_mix(a,b,c,d); a += d;
    f_mix(b,c,d,a); b += c;
    f_mix(c,d,a,b);
    f_mix(d,a,b,c);
    f_mix(a,b,c,d); a += d;
    f_mix(b,c,d,a); b += c;
    f_mix(c,d,a,b);
    f_mix(d,a,b,c);

    f_ktr(a,b,c,d, 4); f_ktr(b,c,d,a, 6); f_ktr(c,d,a,b, 8); f_ktr(d,a,b,c,10); 
    f_ktr(a,b,c,d,12); f_ktr(b,c,d,a,14); f_ktr(c,d,a,b,16); f_ktr(d,a,b,c,18); 
    f_ktr(a,d,c,b,20); f_ktr(b,a,d,c,22); f_ktr(c,b,a,d,24); f_ktr(d,c,b,a,26); 
    f_ktr(a,d,c,b,28); f_ktr(b,a,d,c,30); f_ktr(c,b,a,d,32); f_ktr(d,c,b,a,34); 

    b_mix(a,b,c,d);
    b_mix(b,c,d,a); c -= b;
    b_mix(c,d,a,b); d -= a;
    b_mix(d,a,b,c);
    b_mix(a,b,c,d);
    b_mix(b,c,d,a); c -= b;
    b_mix(c,d,a,b); d -= a;
    b_mix(d,a,b,c);

    out_blk[0] = a - l_key[36]; out_blk[1] = b - l_key[37];
    out_blk[2] = c - l_key[38]; out_blk[3] = d - l_key[39];
};

void mars_decrypt(MarsContext *ctx,
		  const u4byte in_blk[4], u4byte out_blk[4])
{   
    u4byte  a, b, c, d, l, m, r;
    u4byte *l_key = ctx->l_key;

    d = in_blk[0] + l_key[36]; c = in_blk[1] + l_key[37];
    b = in_blk[2] + l_key[38]; a = in_blk[3] + l_key[39];

    f_mix(a,b,c,d); a += d;
    f_mix(b,c,d,a); b += c;
    f_mix(c,d,a,b); 
    f_mix(d,a,b,c);
    f_mix(a,b,c,d); a += d;
    f_mix(b,c,d,a); b += c;
    f_mix(c,d,a,b);
    f_mix(d,a,b,c);

    r_ktr(a,b,c,d,34); r_ktr(b,c,d,a,32); r_ktr(c,d,a,b,30); r_ktr(d,a,b,c,28);
    r_ktr(a,b,c,d,26); r_ktr(b,c,d,a,24); r_ktr(c,d,a,b,22); r_ktr(d,a,b,c,20);
    r_ktr(a,d,c,b,18); r_ktr(b,a,d,c,16); r_ktr(c,b,a,d,14); r_ktr(d,c,b,a,12);
    r_ktr(a,d,c,b,10); r_ktr(b,a,d,c, 8); r_ktr(c,b,a,d, 6); r_ktr(d,c,b,a, 4);

    b_mix(a,b,c,d);
    b_mix(b,c,d,a); c -= b;
    b_mix(c,d,a,b); d -= a;
    b_mix(d,a,b,c);
    b_mix(a,b,c,d);
    b_mix(b,c,d,a); c -= b;
    b_mix(c,d,a,b); d -= a;
    b_mix(d,a,b,c);

    out_blk[0] = d - l_key[0]; out_blk[1] = c - l_key[1];
    out_blk[2] = b - l_key[2]; out_blk[3] = a - l_key[3];
}
