/*
  Copyright (C) 1999 Aladdin Enterprises.  All rights reserved.

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.

  L. Peter Deutsch
  ghost@aladdin.com

 */
/*$Id: md5.c $ */
/*
  Independent implementation of MD5 (RFC 1321).

  This code implements the MD5 Algorithm defined in RFC 1321.
  It is derived directly from the text of the RFC and not from the
  reference implementation.

  The original and principal author of md5.c is L. Peter Deutsch
  <ghost@aladdin.com>.  Other authors are noted in the change history
  that follows (in reverse chronological order):

  *** ALTERED 2003: make it compile in 16bit Turbo C ***
  1999-11-04 lpd Edited comments slightly for automatic TOC extraction.
  1999-10-18 lpd Fixed typo in header comment (ansi2knr rather than md5).
  1999-05-03 lpd Original version.
 */

#include "md5.h"
#include <mem.h> /* ALTERED */

#ifdef TEST
/*
 * Compile with -DTEST to create a self-contained executable test program.
 * The test program should print out the same values as given in section
 * A.5 of RFC 1321, reproduced below.
 */
#include <string.h>
main()
{
    static const char *const test[8] = {
	"", /*d41d8cd98f00b204e9800998ecf8427e*/
	" ",
	"a", /*0cc175b9c0f1b6a831c399e269772661*/
	"abc", /*900150983cd24fb0d6963f7d28e17f72*/
	"message digest", /*f96b697d7cb7938d525a2f31aaf161d0*/
	"abcdefghijklmnopqrstuvwxyz", /*c3fcd3d76192e4007dfb496cca67e13b*/
	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789",
				/*d174ab98d277d9f5a5611c2c9f419d9f*/
	"12345678901234567890123456789012345678901234567890123456789012345678901234567890" /*57edf4a22be3c955ac49da2e2107b67a*/
    };
    int i;

    for (i = 0; i < 7; ++i) {
	md5_state_t state;
	md5_byte_t digest[16];
	int di;

	md5_init(&state);
	md5_append(&state, (const md5_byte_t *)test[i], strlen(test[i]));
	md5_finish(&state, digest);
	printf("MD5 (\"%s\") = ", test[i]);
	for (di = 0; di < 16; ++di)
	    printf("%02x", digest[di]);
	printf("\n");
    }
    return 0;
}
#endif /* TEST */


/*
 * For reference, here is the program that computed the T values.
 */
#if 0
#include <math.h>
main()
{
    int i;
    for (i = 1; i <= 64; ++i) {
	unsigned long v = (unsigned long)(4294967296.0 * fabs(sin((double)i)));
	printf("#define T%d 0x%08lx\n", i, v);
    }
    return 0;
}
#endif
/*
 * End of T computation program.
 */
#define T1 0xd76aa478L
#define T2 0xe8c7b756L
#define T3 0x242070dbL
#define T4 0xc1bdceeeL
#define T5 0xf57c0fafL
#define T6 0x4787c62aL
#define T7 0xa8304613L
#define T8 0xfd469501L
#define T9 0x698098d8L
#define T10 0x8b44f7afL
#define T11 0xffff5bb1L
#define T12 0x895cd7beL
#define T13 0x6b901122L
#define T14 0xfd987193L
#define T15 0xa679438eL
#define T16 0x49b40821L
#define T17 0xf61e2562L
#define T18 0xc040b340L
#define T19 0x265e5a51L
#define T20 0xe9b6c7aaL
#define T21 0xd62f105dL
#define T22 0x02441453L
#define T23 0xd8a1e681L
#define T24 0xe7d3fbc8L
#define T25 0x21e1cde6L
#define T26 0xc33707d6L
#define T27 0xf4d50d87L
#define T28 0x455a14edL
#define T29 0xa9e3e905L
#define T30 0xfcefa3f8L
#define T31 0x676f02d9L
#define T32 0x8d2a4c8aL
#define T33 0xfffa3942L
#define T34 0x8771f681L
#define T35 0x6d9d6122L
#define T36 0xfde5380cL
#define T37 0xa4beea44L
#define T38 0x4bdecfa9L
#define T39 0xf6bb4b60L
#define T40 0xbebfbc70L
#define T41 0x289b7ec6L
#define T42 0xeaa127faL
#define T43 0xd4ef3085L
#define T44 0x04881d05L
#define T45 0xd9d4d039L
#define T46 0xe6db99e5L
#define T47 0x1fa27cf8L
#define T48 0xc4ac5665L
#define T49 0xf4292244L
#define T50 0x432aff97L
#define T51 0xab9423a7L
#define T52 0xfc93a039L
#define T53 0x655b59c3L
#define T54 0x8f0ccc92L
#define T55 0xffeff47dL
#define T56 0x85845dd1L
#define T57 0x6fa87e4fL
#define T58 0xfe2ce6e0L
#define T59 0xa3014314L
#define T60 0x4e0811a1L
#define T61 0xf7537e82L
#define T62 0xbd3af235L
#define T63 0x2ad7d2bbL
#define T64 0xeb86d391L

static void
md5_process(md5_state_t *pms, const md5_byte_t *data /*[64]*/)
{
    md5_word_t
	a = pms->abcd[0], b = pms->abcd[1],
	c = pms->abcd[2], d = pms->abcd[3];
    md5_word_t t;

#ifndef ARCH_IS_BIG_ENDIAN
# define ARCH_IS_BIG_ENDIAN 1	/* slower, default implementation */
#endif
#if ARCH_IS_BIG_ENDIAN

    /*
     * On big-endian machines, we must arrange the bytes in the right
     * order.  (This also works on machines of unknown byte order.)
     */
    md5_word_t X[16];
    const md5_byte_t *xp = data;
    int i;

    for (i = 0; i < 16; ++i, xp += 4)
	X[i] = xp[0] + (xp[1] << 8) + (xp[2] << 16) + (xp[3] << 24);

#else  /* !ARCH_IS_BIG_ENDIAN */

    /*
     * On little-endian machines, we can process properly aligned data
     * without copying it.
     */
    md5_word_t xbuf[16];
    const md5_word_t *X;

    if (!((data - (const md5_byte_t *)0) & 3)) {
	/* data are properly aligned */
	X = (const md5_word_t *)data;
    } else {
	/* not aligned */
	memcpy(xbuf, data, 64);
	X = xbuf;
    }
#endif

#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32 - (n))))

    /* Round 1. */
    /* Let [abcd k s i] denote the operation
       a = b + ((a + F(b,c,d) + X[k] + T[i]) <<< s). */
#define F(x, y, z) (((x) & (y)) | (~(x) & (z)))
#define SET(a, b, c, d, k, s, Ti)\
  t = a + F(b,c,d) + X[k] + Ti;\
  a = ROTATE_LEFT(t, s) + b
    /* Do the following 16 operations. */
    SET(a, b, c, d,  0,  7,  T1);
    SET(d, a, b, c,  1, 12,  T2);
    SET(c, d, a, b,  2, 17,  T3);
    SET(b, c, d, a,  3, 22,  T4);
    SET(a, b, c, d,  4,  7,  T5);
    SET(d, a, b, c,  5, 12,  T6);
    SET(c, d, a, b,  6, 17,  T7);
    SET(b, c, d, a,  7, 22,  T8);
    SET(a, b, c, d,  8,  7,  T9);
    SET(d, a, b, c,  9, 12, T10);
    SET(c, d, a, b, 10, 17, T11);
    SET(b, c, d, a, 11, 22, T12);
    SET(a, b, c, d, 12,  7, T13);
    SET(d, a, b, c, 13, 12, T14);
    SET(c, d, a, b, 14, 17, T15);
    SET(b, c, d, a, 15, 22, T16);
#undef SET

     /* Round 2. */
     /* Let [abcd k s i] denote the operation
          a = b + ((a + G(b,c,d) + X[k] + T[i]) <<< s). */
#define G(x, y, z) (((x) & (z)) | ((y) & ~(z)))
#define SET(a, b, c, d, k, s, Ti)\
  t = a + G(b,c,d) + X[k] + Ti;\
  a = ROTATE_LEFT(t, s) + b
     /* Do the following 16 operations. */
    SET(a, b, c, d,  1,  5, T17);
    SET(d, a, b, c,  6,  9, T18);
    SET(c, d, a, b, 11, 14, T19);
    SET(b, c, d, a,  0, 20, T20);
    SET(a, b, c, d,  5,  5, T21);
    SET(d, a, b, c, 10,  9, T22);
    SET(c, d, a, b, 15, 14, T23);
    SET(b, c, d, a,  4, 20, T24);
    SET(a, b, c, d,  9,  5, T25);
    SET(d, a, b, c, 14,  9, T26);
    SET(c, d, a, b,  3, 14, T27);
    SET(b, c, d, a,  8, 20, T28);
    SET(a, b, c, d, 13,  5, T29);
    SET(d, a, b, c,  2,  9, T30);
    SET(c, d, a, b,  7, 14, T31);
    SET(b, c, d, a, 12, 20, T32);
#undef SET

     /* Round 3. */
     /* Let [abcd k s t] denote the operation
	  a = b + ((a + H(b,c,d) + X[k] + T[i]) <<< s). */
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define SET(a, b, c, d, k, s, Ti)\
  t = a + H(b,c,d) + X[k] + Ti;\
  a = ROTATE_LEFT(t, s) + b
     /* Do the following 16 operations. */
    SET(a, b, c, d,  5,  4, T33);
    SET(d, a, b, c,  8, 11, T34);
    SET(c, d, a, b, 11, 16, T35);
    SET(b, c, d, a, 14, 23, T36);
    SET(a, b, c, d,  1,  4, T37);
    SET(d, a, b, c,  4, 11, T38);
    SET(c, d, a, b,  7, 16, T39);
    SET(b, c, d, a, 10, 23, T40);
    SET(a, b, c, d, 13,  4, T41);
    SET(d, a, b, c,  0, 11, T42);
    SET(c, d, a, b,  3, 16, T43);
    SET(b, c, d, a,  6, 23, T44);
    SET(a, b, c, d,  9,  4, T45);
    SET(d, a, b, c, 12, 11, T46);
    SET(c, d, a, b, 15, 16, T47);
    SET(b, c, d, a,  2, 23, T48);
#undef SET

     /* Round 4. */
     /* Let [abcd k s t] denote the operation
          a = b + ((a + I(b,c,d) + X[k] + T[i]) <<< s). */
#define I(x, y, z) ((y) ^ ((x) | ~(z)))
#define SET(a, b, c, d, k, s, Ti)\
  t = a + I(b,c,d) + X[k] + Ti;\
  a = ROTATE_LEFT(t, s) + b
     /* Do the following 16 operations. */
    SET(a, b, c, d,  0,  6, T49);
    SET(d, a, b, c,  7, 10, T50);
    SET(c, d, a, b, 14, 15, T51);
    SET(b, c, d, a,  5, 21, T52);
    SET(a, b, c, d, 12,  6, T53);
    SET(d, a, b, c,  3, 10, T54);
    SET(c, d, a, b, 10, 15, T55);
    SET(b, c, d, a,  1, 21, T56);
    SET(a, b, c, d,  8,  6, T57);
    SET(d, a, b, c, 15, 10, T58);
    SET(c, d, a, b,  6, 15, T59);
    SET(b, c, d, a, 13, 21, T60);
    SET(a, b, c, d,  4,  6, T61);
    SET(d, a, b, c, 11, 10, T62);
    SET(c, d, a, b,  2, 15, T63);
    SET(b, c, d, a,  9, 21, T64);
#undef SET

     /* Then perform the following additions. (That is increment each
        of the four registers by the value it had before this block
        was started.) */
    pms->abcd[0] += a;
    pms->abcd[1] += b;
    pms->abcd[2] += c;
    pms->abcd[3] += d;
}

void
md5_init(md5_state_t *pms)
{
    pms->count[0] = pms->count[1] = 0;
    pms->abcd[0] = 0x67452301L;
    pms->abcd[1] = 0xefcdab89L;
    pms->abcd[2] = 0x98badcfeL;
    pms->abcd[3] = 0x10325476L;
}

void
md5_append(md5_state_t *pms, const md5_byte_t *data, int nbytes)
{
    const md5_byte_t *p = data;
    int left = nbytes;
    int offset = (int) ( (pms->count[0] >> 3) & 63 );
      /* ALTERED: typecast to int */
    md5_word_t nbits = (md5_word_t)(nbytes << 3);

    if (nbytes <= 0)
	return;

    /* Update the message length. */
    pms->count[1] += nbytes >> 29;
    pms->count[0] += nbits;
    if (pms->count[0] < nbits)
	pms->count[1]++;

    /* Process an initial partial block. */
    if (offset) {
	int copy = (offset + nbytes > 64 ? 64 - offset : nbytes);

	memcpy(pms->buf + offset, p, copy);
	if (offset + copy < 64)
	    return;
	p += copy;
	left -= copy;
	md5_process(pms, pms->buf);
    }

    /* Process full blocks. */
    for (; left >= 64; p += 64, left -= 64)
	md5_process(pms, p);

    /* Process a final partial block. */
    if (left)
	memcpy(pms->buf, p, left);
}

void
md5_finish(md5_state_t *pms, md5_byte_t digest[16])
{
    static const md5_byte_t pad[64] = {
	0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
    };
    md5_byte_t data[8];
    int i;

    /* Save the length before padding. */
    for (i = 0; i < 8; ++i)
	data[i] = (md5_byte_t)(pms->count[i >> 2] >> ((i & 3) << 3));
    /* Pad to 56 bytes mod 64. */
    md5_append(pms, pad, (int) ( ((55 - (pms->count[0] >> 3)) & 63) + 1 ));
      /* ALTERED: typecast to int */
    /* Append the length. */
    md5_append(pms, data, 8);
    for (i = 0; i < 16; ++i)
	digest[i] = (md5_byte_t)(pms->abcd[i >> 2] >> ((i & 3) << 3));
}
