/*
 * md5.ec -- An eC adaptation of Alexander Peslyak public domain MD5 implementation
 * --------------------------------------------------------------------------------
 * This is an OpenSSL-compatible implementation of the RSA Data Security, Inc.
 * MD5 Message-Digest Algorithm (RFC 1321).
 *
 * Homepage:
 * http://openwall.info/wiki/people/solar/software/public-domain-source-code/md5
 *
 * Author:
 * Alexander Peslyak, better known as Solar Designer <solar at openwall.com>
 *
 * This software was written by Alexander Peslyak in 2001.  No copyright is
 * claimed, and the software is hereby placed in the public domain.
 * In case this attempt to disclaim copyright and place the software in the
 * public domain is deemed null and void, then the software is
 * Copyright (c) 2001 Alexander Peslyak and it is hereby released to the
 * general public under the following terms:
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted.
 *
 * There's ABSOLUTELY NO WARRANTY, express or implied.
 *
 * (This is a heavily cut-down "BSD license".)
 *
 * This differs from Colin Plumb's older public domain implementation in that
 * no exactly 32-bit integer data type is required (any 32-bit or wider
 * unsigned integer data type will do), there's no compile-time endianness
 * configuration, and the function prototypes match OpenSSL's.  No code from
 * Colin Plumb's implementation has been reused; this comment merely compares
 * the properties of the two independent implementations.
 *
 * The primary goals of this implementation are portability and ease of use.
 * It is meant to be fast, but not as fast as possible.  Some known
 * optimizations are not included to reduce source code size and avoid
 * compile-time configuration.
 */

struct MD5_CTX
{
   uint32 lo, hi;
   uint32 a, b, c, d;
   byte buffer[64];
   uint32 block[16];
} MD5_CTX;

/*
 * The basic MD5 functions.
 *
 * F and G are optimized compared to their RFC 1321 definitions for
 * architectures that lack an AND-NOT instruction, just like in Colin Plumb's
 * implementation.
 */
#define F(x, y, z)         ((z) ^ ((x) & ((y) ^ (z))))
#define G(x, y, z)         ((y) ^ ((z) & ((x) ^ (y))))
#define H(x, y, z)         (((x) ^ (y)) ^ (z))
#define H2(x, y, z)        ((x) ^ ((y) ^ (z)))
#define I(x, y, z)         ((y) ^ ((x) | ~(z)))

/*
 * The MD5 transformation for all four rounds.
 */
#define STEP(f, a, b, c, d, x, t, s) \
   (a) += f((b), (c), (d)) + (x) + (t); \
   (a) = (((a) << (s)) | (((a) & 0xffffffff) >> (32 - (s)))); \
   (a) += (b);

/*
 * SET reads 4 input bytes in little-endian byte order and stores them
 * in a properly aligned word in host byte order.
 *
 * The check for little-endian architectures that tolerate unaligned
 * memory accesses is just an optimization.  Nothing will break if it
 * doesn't work.
 */
#if defined(__i386__) || defined(__x86_64__) || defined(__vax__)
#  define SET(n) (*(uint32 *)&ptr[(n) * 4])
#  define GET(n) SET(n)
#else
#  define SET(n) \
      (ctx.block[(n)] = \
      (uint32)ptr[(n) * 4] | \
      ((uint32)ptr[(n) * 4 + 1] << 8) | \
      ((uint32)ptr[(n) * 4 + 2] << 16) | \
      ((uint32)ptr[(n) * 4 + 3] << 24))
#  define GET(n) (ctx.block[(n)])
#endif

/*
 * This processes one or more 64-byte data blocks, but does NOT update
 * the bit counters.  There are no alignment requirements.
 */
static const void *body(MD5_CTX ctx, const void *data, uint size)
{
   const byte *ptr = (const byte *)data;
   uint32 a = ctx.a, b = ctx.b, c = ctx.c, d = ctx.d;
   do
   {
      uint32 saved_a = a, saved_b = b, saved_c = c, saved_d = d;

      // Round 1
      STEP(F, a, b, c, d, SET(0), 0xd76aa478, 7)
      STEP(F, d, a, b, c, SET(1), 0xe8c7b756, 12)
      STEP(F, c, d, a, b, SET(2), 0x242070db, 17)
      STEP(F, b, c, d, a, SET(3), 0xc1bdceee, 22)
      STEP(F, a, b, c, d, SET(4), 0xf57c0faf, 7)
      STEP(F, d, a, b, c, SET(5), 0x4787c62a, 12)
      STEP(F, c, d, a, b, SET(6), 0xa8304613, 17)
      STEP(F, b, c, d, a, SET(7), 0xfd469501, 22)
      STEP(F, a, b, c, d, SET(8), 0x698098d8, 7)
      STEP(F, d, a, b, c, SET(9), 0x8b44f7af, 12)
      STEP(F, c, d, a, b, SET(10), 0xffff5bb1, 17)
      STEP(F, b, c, d, a, SET(11), 0x895cd7be, 22)
      STEP(F, a, b, c, d, SET(12), 0x6b901122, 7)
      STEP(F, d, a, b, c, SET(13), 0xfd987193, 12)
      STEP(F, c, d, a, b, SET(14), 0xa679438e, 17)
      STEP(F, b, c, d, a, SET(15), 0x49b40821, 22)

      // Round 2
      STEP(G, a, b, c, d, GET(1), 0xf61e2562, 5)
      STEP(G, d, a, b, c, GET(6), 0xc040b340, 9)
      STEP(G, c, d, a, b, GET(11), 0x265e5a51, 14)
      STEP(G, b, c, d, a, GET(0), 0xe9b6c7aa, 20)
      STEP(G, a, b, c, d, GET(5), 0xd62f105d, 5)
      STEP(G, d, a, b, c, GET(10), 0x02441453, 9)
      STEP(G, c, d, a, b, GET(15), 0xd8a1e681, 14)
      STEP(G, b, c, d, a, GET(4), 0xe7d3fbc8, 20)
      STEP(G, a, b, c, d, GET(9), 0x21e1cde6, 5)
      STEP(G, d, a, b, c, GET(14), 0xc33707d6, 9)
      STEP(G, c, d, a, b, GET(3), 0xf4d50d87, 14)
      STEP(G, b, c, d, a, GET(8), 0x455a14ed, 20)
      STEP(G, a, b, c, d, GET(13), 0xa9e3e905, 5)
      STEP(G, d, a, b, c, GET(2), 0xfcefa3f8, 9)
      STEP(G, c, d, a, b, GET(7), 0x676f02d9, 14)
      STEP(G, b, c, d, a, GET(12), 0x8d2a4c8a, 20)

      // Round 3
      STEP(H, a, b, c, d, GET(5), 0xfffa3942, 4)
      STEP(H2, d, a, b, c, GET(8), 0x8771f681, 11)
      STEP(H, c, d, a, b, GET(11), 0x6d9d6122, 16)
      STEP(H2, b, c, d, a, GET(14), 0xfde5380c, 23)
      STEP(H, a, b, c, d, GET(1), 0xa4beea44, 4)
      STEP(H2, d, a, b, c, GET(4), 0x4bdecfa9, 11)
      STEP(H, c, d, a, b, GET(7), 0xf6bb4b60, 16)
      STEP(H2, b, c, d, a, GET(10), 0xbebfbc70, 23)
      STEP(H, a, b, c, d, GET(13), 0x289b7ec6, 4)
      STEP(H2, d, a, b, c, GET(0), 0xeaa127fa, 11)
      STEP(H, c, d, a, b, GET(3), 0xd4ef3085, 16)
      STEP(H2, b, c, d, a, GET(6), 0x04881d05, 23)
      STEP(H, a, b, c, d, GET(9), 0xd9d4d039, 4)
      STEP(H2, d, a, b, c, GET(12), 0xe6db99e5, 11)
      STEP(H, c, d, a, b, GET(15), 0x1fa27cf8, 16)
      STEP(H2, b, c, d, a, GET(2), 0xc4ac5665, 23)

      // Round 4
      STEP(I, a, b, c, d, GET(0), 0xf4292244, 6)
      STEP(I, d, a, b, c, GET(7), 0x432aff97, 10)
      STEP(I, c, d, a, b, GET(14), 0xab9423a7, 15)
      STEP(I, b, c, d, a, GET(5), 0xfc93a039, 21)
      STEP(I, a, b, c, d, GET(12), 0x655b59c3, 6)
      STEP(I, d, a, b, c, GET(3), 0x8f0ccc92, 10)
      STEP(I, c, d, a, b, GET(10), 0xffeff47d, 15)
      STEP(I, b, c, d, a, GET(1), 0x85845dd1, 21)
      STEP(I, a, b, c, d, GET(8), 0x6fa87e4f, 6)
      STEP(I, d, a, b, c, GET(15), 0xfe2ce6e0, 10)
      STEP(I, c, d, a, b, GET(6), 0xa3014314, 15)
      STEP(I, b, c, d, a, GET(13), 0x4e0811a1, 21)
      STEP(I, a, b, c, d, GET(4), 0xf7537e82, 6)
      STEP(I, d, a, b, c, GET(11), 0xbd3af235, 10)
      STEP(I, c, d, a, b, GET(2), 0x2ad7d2bb, 15)
      STEP(I, b, c, d, a, GET(9), 0xeb86d391, 21)

      a += saved_a;
      b += saved_b;
      c += saved_c;
      d += saved_d;

      ptr += 64;
   } while (size -= 64);

   ctx.a = a;
   ctx.b = b;
   ctx.c = c;
   ctx.d = d;

   return ptr;
}

void MD5Init(MD5_CTX ctx)
{
   ctx =
   {
      a = 0x67452301;
      b = 0xefcdab89;
      c = 0x98badcfe;
      d = 0x10325476;
   };
}

void MD5Update(MD5_CTX ctx, const byte *data, uint size)
{
   uint32 saved_lo = ctx.lo;
   uint used = saved_lo & 0x3f;

   if((ctx.lo = (saved_lo + size) & 0x1fffffff) < saved_lo)
      ctx.hi++;
   ctx.hi += size >> 29;

   if(used)
   {
      uint available = 64 - used;

      if(size < available)
      {
         memcpy(&ctx.buffer[used], data, size);
         return;
      }

      memcpy(&ctx.buffer[used], data, available);
      data = (const byte *)data + available;
      size -= available;
      body(ctx, ctx.buffer, 64);
   }

   if(size >= 64)
   {
      data = body(ctx, data, size & ~(uint)0x3f);
      size &= 0x3f;
   }

   memcpy(ctx.buffer, data, size);
}

void MD5Final(byte *result, MD5_CTX ctx)
{
   uint used = ctx.lo & 0x3f;
   uint available = 64 - used;

   ctx.buffer[used++] = 0x80;

   if(available < 8)
   {
      memset(&ctx.buffer[used], 0, available);
      body(ctx, ctx.buffer, 64);
      used = 0;
      available = 64;
   }

   memset(&ctx.buffer[used], 0, available - 8);

   ctx.lo <<= 3;
   ctx.buffer[56] = (byte)ctx.lo;
   ctx.buffer[57] = ctx.lo >> 8;
   ctx.buffer[58] = ctx.lo >> 16;
   ctx.buffer[59] = ctx.lo >> 24;
   ctx.buffer[60] = (byte)ctx.hi;
   ctx.buffer[61] = ctx.hi >> 8;
   ctx.buffer[62] = ctx.hi >> 16;
   ctx.buffer[63] = ctx.hi >> 24;

   body(ctx, ctx.buffer, 64);

   result[0] = (byte)ctx.a;
   result[1] = ctx.a >> 8;
   result[2] = ctx.a >> 16;
   result[3] = ctx.a >> 24;
   result[4] = (byte)ctx.b;
   result[5] = ctx.b >> 8;
   result[6] = ctx.b >> 16;
   result[7] = ctx.b >> 24;
   result[8] = (byte)ctx.c;
   result[9] = ctx.c >> 8;
   result[10] = ctx.c >> 16;
   result[11] = ctx.c >> 24;
   result[12] = (byte)ctx.d;
   result[13] = ctx.d >> 8;
   result[14] = ctx.d >> 16;
   result[15] = ctx.d >> 24;

   memset(ctx, 0, sizeof(MD5_CTX));
}

void MD5Digest(const char * string, int len, char * output)
{
   byte bytes[16];
   int c;
   MD5_CTX ctx;
   MD5Init(&ctx);
   MD5Update(&ctx, (byte *)string, len);
   MD5Final(bytes, &ctx);
   len = 0;
   for(c = 0; c<16; c++)
   {
      sprintf(output + len, "%02x", bytes[c]);
      len += 2;
   }
}

void MD5Digest64(const char * string, int len, uint64 * output)
{
   byte bytes[16];
   MD5_CTX ctx;
   MD5Init(&ctx);
   MD5Update(&ctx, (byte *)string, len);
   MD5Final(bytes, &ctx);
   output[0] = ((uint64)bytes[ 0] << 56) | ((uint64)bytes[ 1] << 48) | ((uint64)bytes[ 2] << 40) | ((uint64)bytes[ 3] << 32) |
               ((uint64)bytes[ 4] << 24) | ((uint64)bytes[ 5] << 16) | ((uint64)bytes[ 6] <<  8) | ((uint64)bytes[ 7]      );
   output[1] = ((uint64)bytes[ 8] << 56) | ((uint64)bytes[ 9] << 48) | ((uint64)bytes[10] << 40) | ((uint64)bytes[11] << 32) |
               ((uint64)bytes[12] << 24) | ((uint64)bytes[13] << 16) | ((uint64)bytes[14] <<  8) | ((uint64)bytes[15]      );
}