/* LibTomCrypt, modular cryptographic library -- Tom St Denis
 *
 * LibTomCrypt is a library that provides various cryptographic
 * algorithms in a highly modular and flexible manner.
 *
 * The library is free for all purposes without any express
 * guarantee it works.
 *
 * Tom St Denis, tomstdenis@iahu.ca, http://libtomcrypt.org
 */

/* SHA1 code by Tom St Denis */
#include "mycrypt.h"

#ifdef SHA1

const struct _hash_descriptor sha1_desc =
{
    "sha1",
    2,
    20,
    64,

    /* DER identifier */
    { 0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2B, 0x0E, 
      0x03, 0x02, 0x1A, 0x05, 0x00, 0x04, 0x14 },
    15,

    &sha1_init,
    &sha1_process,
    &sha1_done,
    &sha1_test
};

#define F0(x,y,z)  (z ^ (x & (y ^ z)))
#define F1(x,y,z)  (x ^ y ^ z)
#define F2(x,y,z)  ((x & y) | (z & (x | y)))
#define F3(x,y,z)  (x ^ y ^ z)

#ifdef CLEAN_STACK
static void _sha1_compress(hash_state *md, unsigned char *buf)
#else
static void sha1_compress(hash_state *md, unsigned char *buf)
#endif
{
    ulong32 a,b,c,d,e,W[80],i;
#ifdef SMALL_CODE
    ulong32 t;
#endif

    /* copy the state into 512-bits into W[0..15] */
    for (i = 0; i < 16; i++) {
        LOAD32H(W[i], buf + (4*i));
    }

    /* copy state */
    a = md->sha1.state[0];
    b = md->sha1.state[1];
    c = md->sha1.state[2];
    d = md->sha1.state[3];
    e = md->sha1.state[4];

    /* expand it */
    for (i = 16; i < 80; i++) {
        W[i] = ROL(W[i-3] ^ W[i-8] ^ W[i-14] ^ W[i-16], 1); 
    }

    /* compress */
    /* round one */
    #define FF0(a,b,c,d,e,i) e = (ROL(a, 5) + F0(b,c,d) + e + W[i] + 0x5a827999UL); b = ROL(b, 30);
    #define FF1(a,b,c,d,e,i) e = (ROL(a, 5) + F1(b,c,d) + e + W[i] + 0x6ed9eba1UL); b = ROL(b, 30);
    #define FF2(a,b,c,d,e,i) e = (ROL(a, 5) + F2(b,c,d) + e + W[i] + 0x8f1bbcdcUL); b = ROL(b, 30);
    #define FF3(a,b,c,d,e,i) e = (ROL(a, 5) + F3(b,c,d) + e + W[i] + 0xca62c1d6UL); b = ROL(b, 30);
 
#ifdef SMALL_CODE
 
    for (i = 0; i < 20; ) {
       FF0(a,b,c,d,e,i++); t = e; e = d; d = c; c = b; b = a; a = t;
    }

    for (; i < 40; ) {
       FF1(a,b,c,d,e,i++); t = e; e = d; d = c; c = b; b = a; a = t;
    }

    for (; i < 60; ) {
       FF2(a,b,c,d,e,i++); t = e; e = d; d = c; c = b; b = a; a = t;
    }

    for (; i < 80; ) {
       FF3(a,b,c,d,e,i++); t = e; e = d; d = c; c = b; b = a; a = t;
    }

#else

    for (i = 0; i < 20; ) {
       FF0(a,b,c,d,e,i++);
       FF0(e,a,b,c,d,i++);
       FF0(d,e,a,b,c,i++);
       FF0(c,d,e,a,b,i++);
       FF0(b,c,d,e,a,i++);
    }

    /* round two */
    for (; i < 40; )  { 
       FF1(a,b,c,d,e,i++);
       FF1(e,a,b,c,d,i++);
       FF1(d,e,a,b,c,i++);
       FF1(c,d,e,a,b,i++);
       FF1(b,c,d,e,a,i++);
    }

    /* round three */
    for (; i < 60; )  { 
       FF2(a,b,c,d,e,i++);
       FF2(e,a,b,c,d,i++);
       FF2(d,e,a,b,c,i++);
       FF2(c,d,e,a,b,i++);
       FF2(b,c,d,e,a,i++);
    }

    /* round four */
    for (; i < 80; )  { 
       FF3(a,b,c,d,e,i++);
       FF3(e,a,b,c,d,i++);
       FF3(d,e,a,b,c,i++);
       FF3(c,d,e,a,b,i++);
       FF3(b,c,d,e,a,i++);
    }
#endif

    #undef FF0
    #undef FF1
    #undef FF2
    #undef FF3

    /* store */
    md->sha1.state[0] = md->sha1.state[0] + a;
    md->sha1.state[1] = md->sha1.state[1] + b;
    md->sha1.state[2] = md->sha1.state[2] + c;
    md->sha1.state[3] = md->sha1.state[3] + d;
    md->sha1.state[4] = md->sha1.state[4] + e;
}

#ifdef CLEAN_STACK
static void sha1_compress(hash_state *md, unsigned char *buf)
{
   _sha1_compress(md, buf);
   burn_stack(sizeof(ulong32) * 87);
}
#endif

void sha1_init(hash_state * md)
{
   _ARGCHK(md != NULL);
   md->sha1.state[0] = 0x67452301UL;
   md->sha1.state[1] = 0xefcdab89UL;
   md->sha1.state[2] = 0x98badcfeUL;
   md->sha1.state[3] = 0x10325476UL;
   md->sha1.state[4] = 0xc3d2e1f0UL;
   md->sha1.curlen = 0;
   md->sha1.length = 0;
}

HASH_PROCESS(sha1_process, sha1_compress, sha1, 64)

int sha1_done(hash_state * md, unsigned char *hash)
{
    int i;

    _ARGCHK(md != NULL);
    _ARGCHK(hash != NULL);

    if (md->sha1.curlen >= sizeof(md->sha1.buf)) {
       return CRYPT_INVALID_ARG;
    }

    /* increase the length of the message */
    md->sha1.length += md->sha1.curlen * 8;

    /* append the '1' bit */
    md->sha1.buf[md->sha1.curlen++] = (unsigned char)0x80;

    /* if the length is currently above 56 bytes we append zeros
     * then compress.  Then we can fall back to padding zeros and length
     * encoding like normal.
     */
    if (md->sha1.curlen > 56) {
        while (md->sha1.curlen < 64) {
            md->sha1.buf[md->sha1.curlen++] = (unsigned char)0;
        }
        sha1_compress(md, md->sha1.buf);
        md->sha1.curlen = 0;
    }

    /* pad upto 56 bytes of zeroes */
    while (md->sha1.curlen < 56) {
        md->sha1.buf[md->sha1.curlen++] = (unsigned char)0;
    }

    /* store length */
    STORE64H(md->sha1.length, md->sha1.buf+56);
    sha1_compress(md, md->sha1.buf);

    /* copy output */
    for (i = 0; i < 5; i++) {
        STORE32H(md->sha1.state[i], hash+(4*i));
    }
#ifdef CLEAN_STACK
    zeromem(md, sizeof(hash_state));
#endif
    return CRYPT_OK;
}

int  sha1_test(void)
{
 #ifndef LTC_TEST
    return CRYPT_NOP;
 #else    
  static const struct {
      char *msg;
      unsigned char hash[20];
  } tests[] = {
    { "abc",
      { 0xa9, 0x99, 0x3e, 0x36, 0x47, 0x06, 0x81, 0x6a,
        0xba, 0x3e, 0x25, 0x71, 0x78, 0x50, 0xc2, 0x6c,
        0x9c, 0xd0, 0xd8, 0x9d }
    },
    { "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq",
      { 0x84, 0x98, 0x3E, 0x44, 0x1C, 0x3B, 0xD2, 0x6E,
        0xBA, 0xAE, 0x4A, 0xA1, 0xF9, 0x51, 0x29, 0xE5,
        0xE5, 0x46, 0x70, 0xF1 }
    }
  };

  int i;
  unsigned char tmp[20];
  hash_state md;

  for (i = 0; i < (int)(sizeof(tests) / sizeof(tests[0]));  i++) {
      sha1_init(&md);
      sha1_process(&md, (unsigned char*)tests[i].msg, (unsigned long)strlen(tests[i].msg));
      sha1_done(&md, tmp);
      if (memcmp(tmp, tests[i].hash, 20) != 0) {
         return CRYPT_FAIL_TESTVECTOR;
      }
  }
  return CRYPT_OK;
  #endif
}

#endif