/*
 *  RFC 1321 compliant MD5 implementation
 *
 *  Based on XySSL: Copyright (C) 2006-2008  Christophe Devine
 *
 *  Copyright (C) 2009  Paul Bakker <polarssl_maintainer at polarssl dot org>
 *
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *    * Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *    * Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *    * Neither the names of PolarSSL or XySSL nor the names of its contributors
 *      may be used to endorse or promote products derived from this software
 *      without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 *  FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 *  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 *  TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 *  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
/*
 *  The MD5 algorithm was designed by Ron Rivest in 1991.
 *
 *  http://www.ietf.org/rfc/rfc1321.txt
 */

#include "md5.h"

#include <string.h>

/*
 * 32-bit integer manipulation macros (little endian)
 */
#ifndef GET_ULONG_LE
#define GET_ULONG_LE(n,b,i)                             \
{                                                       \
    (n) = ( (unsigned long) (b)[(i)    ]       )        \
        | ( (unsigned long) (b)[(i) + 1] <<  8 )        \
        | ( (unsigned long) (b)[(i) + 2] << 16 )        \
        | ( (unsigned long) (b)[(i) + 3] << 24 );       \
}
#endif

#ifndef PUT_ULONG_LE
#define PUT_ULONG_LE(n,b,i)                             \
{                                                       \
    (b)[(i)    ] = (unsigned char) ( (n)       );       \
    (b)[(i) + 1] = (unsigned char) ( (n) >>  8 );       \
    (b)[(i) + 2] = (unsigned char) ( (n) >> 16 );       \
    (b)[(i) + 3] = (unsigned char) ( (n) >> 24 );       \
}
#endif

/*
 * MD5 context setup
 */
void md5_starts(md5_context *ctx) {
   ctx->total[0] = 0;
   ctx->total[1] = 0;

   ctx->state[0] = 0x67452301;
   ctx->state[1] = 0xEFCDAB89;
   ctx->state[2] = 0x98BADCFE;
   ctx->state[3] = 0x10325476;
}

static void md5_process(md5_context *ctx, const unsigned char data[64]) {
   unsigned long X[16], A, B, C, D;

   GET_ULONG_LE(X[ 0], data,  0);
   GET_ULONG_LE(X[ 1], data,  4);
   GET_ULONG_LE(X[ 2], data,  8);
   GET_ULONG_LE(X[ 3], data, 12);
   GET_ULONG_LE(X[ 4], data, 16);
   GET_ULONG_LE(X[ 5], data, 20);
   GET_ULONG_LE(X[ 6], data, 24);
   GET_ULONG_LE(X[ 7], data, 28);
   GET_ULONG_LE(X[ 8], data, 32);
   GET_ULONG_LE(X[ 9], data, 36);
   GET_ULONG_LE(X[10], data, 40);
   GET_ULONG_LE(X[11], data, 44);
   GET_ULONG_LE(X[12], data, 48);
   GET_ULONG_LE(X[13], data, 52);
   GET_ULONG_LE(X[14], data, 56);
   GET_ULONG_LE(X[15], data, 60);

#define S(x,n) ((x << n) | ((x & 0xFFFFFFFF) >> (32 - n)))

#define P(a,b,c,d,k,s,t)                                \
{                                                       \
    a += F(b,c,d) + X[k] + t; a = S(a,s) + b;           \
}

   A = ctx->state[0];
   B = ctx->state[1];
   C = ctx->state[2];
   D = ctx->state[3];

#define F(x,y,z) (z ^ (x & (y ^ z)))

   P(A, B, C, D,  0,  7, 0xD76AA478);
   P(D, A, B, C,  1, 12, 0xE8C7B756);
   P(C, D, A, B,  2, 17, 0x242070DB);
   P(B, C, D, A,  3, 22, 0xC1BDCEEE);
   P(A, B, C, D,  4,  7, 0xF57C0FAF);
   P(D, A, B, C,  5, 12, 0x4787C62A);
   P(C, D, A, B,  6, 17, 0xA8304613);
   P(B, C, D, A,  7, 22, 0xFD469501);
   P(A, B, C, D,  8,  7, 0x698098D8);
   P(D, A, B, C,  9, 12, 0x8B44F7AF);
   P(C, D, A, B, 10, 17, 0xFFFF5BB1);
   P(B, C, D, A, 11, 22, 0x895CD7BE);
   P(A, B, C, D, 12,  7, 0x6B901122);
   P(D, A, B, C, 13, 12, 0xFD987193);
   P(C, D, A, B, 14, 17, 0xA679438E);
   P(B, C, D, A, 15, 22, 0x49B40821);

#undef F

#define F(x,y,z) (y ^ (z & (x ^ y)))

   P(A, B, C, D,  1,  5, 0xF61E2562);
   P(D, A, B, C,  6,  9, 0xC040B340);
   P(C, D, A, B, 11, 14, 0x265E5A51);
   P(B, C, D, A,  0, 20, 0xE9B6C7AA);
   P(A, B, C, D,  5,  5, 0xD62F105D);
   P(D, A, B, C, 10,  9, 0x02441453);
   P(C, D, A, B, 15, 14, 0xD8A1E681);
   P(B, C, D, A,  4, 20, 0xE7D3FBC8);
   P(A, B, C, D,  9,  5, 0x21E1CDE6);
   P(D, A, B, C, 14,  9, 0xC33707D6);
   P(C, D, A, B,  3, 14, 0xF4D50D87);
   P(B, C, D, A,  8, 20, 0x455A14ED);
   P(A, B, C, D, 13,  5, 0xA9E3E905);
   P(D, A, B, C,  2,  9, 0xFCEFA3F8);
   P(C, D, A, B,  7, 14, 0x676F02D9);
   P(B, C, D, A, 12, 20, 0x8D2A4C8A);

#undef F

#define F(x,y,z) (x ^ y ^ z)

   P(A, B, C, D,  5,  4, 0xFFFA3942);
   P(D, A, B, C,  8, 11, 0x8771F681);
   P(C, D, A, B, 11, 16, 0x6D9D6122);
   P(B, C, D, A, 14, 23, 0xFDE5380C);
   P(A, B, C, D,  1,  4, 0xA4BEEA44);
   P(D, A, B, C,  4, 11, 0x4BDECFA9);
   P(C, D, A, B,  7, 16, 0xF6BB4B60);
   P(B, C, D, A, 10, 23, 0xBEBFBC70);
   P(A, B, C, D, 13,  4, 0x289B7EC6);
   P(D, A, B, C,  0, 11, 0xEAA127FA);
   P(C, D, A, B,  3, 16, 0xD4EF3085);
   P(B, C, D, A,  6, 23, 0x04881D05);
   P(A, B, C, D,  9,  4, 0xD9D4D039);
   P(D, A, B, C, 12, 11, 0xE6DB99E5);
   P(C, D, A, B, 15, 16, 0x1FA27CF8);
   P(B, C, D, A,  2, 23, 0xC4AC5665);

#undef F

#define F(x,y,z) (y ^ (x | ~z))

   P(A, B, C, D,  0,  6, 0xF4292244);
   P(D, A, B, C,  7, 10, 0x432AFF97);
   P(C, D, A, B, 14, 15, 0xAB9423A7);
   P(B, C, D, A,  5, 21, 0xFC93A039);
   P(A, B, C, D, 12,  6, 0x655B59C3);
   P(D, A, B, C,  3, 10, 0x8F0CCC92);
   P(C, D, A, B, 10, 15, 0xFFEFF47D);
   P(B, C, D, A,  1, 21, 0x85845DD1);
   P(A, B, C, D,  8,  6, 0x6FA87E4F);
   P(D, A, B, C, 15, 10, 0xFE2CE6E0);
   P(C, D, A, B,  6, 15, 0xA3014314);
   P(B, C, D, A, 13, 21, 0x4E0811A1);
   P(A, B, C, D,  4,  6, 0xF7537E82);
   P(D, A, B, C, 11, 10, 0xBD3AF235);
   P(C, D, A, B,  2, 15, 0x2AD7D2BB);
   P(B, C, D, A,  9, 21, 0xEB86D391);

#undef F

   ctx->state[0] += A;
   ctx->state[1] += B;
   ctx->state[2] += C;
   ctx->state[3] += D;
}

/*
 * MD5 process buffer
 */
void md5_update(md5_context *ctx, const unsigned char *input, int ilen) {
   int fill;
   unsigned long left;

   if(ilen <= 0)
      return;

   left = ctx->total[0] & 0x3F;
   fill = 64 - left;

   ctx->total[0] += ilen;
   ctx->total[0] &= 0xFFFFFFFF;

   if(ctx->total[0] < (unsigned long) ilen)
      ctx->total[1]++;

   if(left && ilen >= fill) {
      memcpy((void *)(ctx->buffer + left),
             input, fill);
      md5_process(ctx, ctx->buffer);
      input += fill;
      ilen  -= fill;
      left = 0;
   }

   while(ilen >= 64) {
      md5_process(ctx, input);
      input += 64;
      ilen  -= 64;
   }

   if(ilen > 0) {
      memcpy((void *)(ctx->buffer + left),
             input, ilen);
   }
}

static const unsigned char md5_padding[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 final digest
 */
void md5_finish(md5_context *ctx, unsigned char output[16]) {
   unsigned long last, padn;
   unsigned long high, low;
   unsigned char msglen[8];

   high = (ctx->total[0] >> 29)
          | (ctx->total[1] <<  3);
   low  = (ctx->total[0] <<  3);

   PUT_ULONG_LE(low,  msglen, 0);
   PUT_ULONG_LE(high, msglen, 4);

   last = ctx->total[0] & 0x3F;
   padn = (last < 56) ? (56 - last) : (120 - last);

   md5_update(ctx, md5_padding, padn);
   md5_update(ctx, msglen, 8);

   PUT_ULONG_LE(ctx->state[0], output,  0);
   PUT_ULONG_LE(ctx->state[1], output,  4);
   PUT_ULONG_LE(ctx->state[2], output,  8);
   PUT_ULONG_LE(ctx->state[3], output, 12);
}

/*
 * output = MD5( input buffer )
 */
void md5(unsigned char *input, int ilen, unsigned char output[16]) {
   md5_context ctx;

   md5_starts(&ctx);
   md5_update(&ctx, input, ilen);
   md5_finish(&ctx, output);
}
