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md4.cpp

/*
 * MD4 (RFC-1320) message digest.
 * Modified from MD5 code by Andrey Panin <pazke@donpac.ru>
 *
 * Written by Solar Designer <solar@openwall.com> in 2001, and placed in
 * the public domain.  There's absolutely no warranty.
 *
 * This differs from Colin Plumb's older public domain implementation in
 * that no 32-bit integer data type is required, there's no compile-time
 * endianness configuration, and the function prototypes match OpenSSL's.
 * The primary goals are portability and ease of use.
 *
 * This implementation 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.
 */

#include "md4.h"

#include <string.h>

/*
 * The basic MD4 functions.
 */
#define F(x, y, z)      ((z) ^ ((x) & ((y) ^ (z))))
#define G(x, y, z)      (((x) & (y)) | ((x) & (z)) | ((y) & (z)))
#define H(x, y, z)      ((x) ^ (y) ^ (z))

/*
 * The MD4 transformation for all four rounds.
 */
#define STEP(f, a, b, c, d, x, s) \
      (a) += f((b), (c), (d)) + (x);       \
      (a) = ((a) << (s)) | ((a) >> (32 - (s)))


/*
 * 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 which tolerate unaligned
 * memory accesses is just an optimization.  Nothing will break if it
 * doesn't work.
 */
#if defined(__i386__) || defined(__x86_64__)
#define SET(n) \
      (*(const quint32 *)&ptr[(n) * 4])
#define GET(n) \
      SET(n)
#else
#define SET(n) \
      (ctx->block[(n)] = \
      (quint32)ptr[(n) * 4] | \
      ((quint32)ptr[(n) * 4 + 1] << 8) | \
      ((quint32)ptr[(n) * 4 + 2] << 16) | \
      ((quint32)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're no alignment requirements.
 */
static const unsigned char *body(struct md4_context *ctx, const unsigned char *data, size_t size)
{
      const unsigned char *ptr;
      quint32 a, b, c, d;
      quint32 saved_a, saved_b, saved_c, saved_d;

      ptr = data;

      a = ctx->a;
      b = ctx->b;
      c = ctx->c;
      d = ctx->d;

      do {
            saved_a = a;
            saved_b = b;
            saved_c = c;
            saved_d = d;

/* Round 1 */
            STEP(F, a, b, c, d, SET( 0),  3);
            STEP(F, d, a, b, c, SET( 1),  7);
            STEP(F, c, d, a, b, SET( 2), 11);
            STEP(F, b, c, d, a, SET( 3), 19);

            STEP(F, a, b, c, d, SET( 4),  3);
            STEP(F, d, a, b, c, SET( 5),  7);
            STEP(F, c, d, a, b, SET( 6), 11);
            STEP(F, b, c, d, a, SET( 7), 19);

            STEP(F, a, b, c, d, SET( 8),  3);
            STEP(F, d, a, b, c, SET( 9),  7);
            STEP(F, c, d, a, b, SET(10), 11);
            STEP(F, b, c, d, a, SET(11), 19);

            STEP(F, a, b, c, d, SET(12),  3);
            STEP(F, d, a, b, c, SET(13),  7);
            STEP(F, c, d, a, b, SET(14), 11);
            STEP(F, b, c, d, a, SET(15), 19);
/* Round 2 */
            STEP(G, a, b, c, d, GET( 0) + 0x5A827999,  3);
            STEP(G, d, a, b, c, GET( 4) + 0x5A827999,  5);
            STEP(G, c, d, a, b, GET( 8) + 0x5A827999,  9);
            STEP(G, b, c, d, a, GET(12) + 0x5A827999, 13);

            STEP(G, a, b, c, d, GET( 1) + 0x5A827999,  3);
            STEP(G, d, a, b, c, GET( 5) + 0x5A827999,  5);
            STEP(G, c, d, a, b, GET( 9) + 0x5A827999,  9);
            STEP(G, b, c, d, a, GET(13) + 0x5A827999, 13);

            STEP(G, a, b, c, d, GET( 2) + 0x5A827999,  3);
            STEP(G, d, a, b, c, GET( 6) + 0x5A827999,  5);
            STEP(G, c, d, a, b, GET(10) + 0x5A827999,  9);
            STEP(G, b, c, d, a, GET(14) + 0x5A827999, 13);

            STEP(G, a, b, c, d, GET( 3) + 0x5A827999,  3);
            STEP(G, d, a, b, c, GET( 7) + 0x5A827999,  5);
            STEP(G, c, d, a, b, GET(11) + 0x5A827999,  9);
            STEP(G, b, c, d, a, GET(15) + 0x5A827999, 13);
/* Round 3 */
            STEP(H, a, b, c, d, GET( 0) + 0x6ED9EBA1,  3);
            STEP(H, d, a, b, c, GET( 8) + 0x6ED9EBA1,  9);
            STEP(H, c, d, a, b, GET( 4) + 0x6ED9EBA1, 11);
            STEP(H, b, c, d, a, GET(12) + 0x6ED9EBA1, 15);

            STEP(H, a, b, c, d, GET( 2) + 0x6ED9EBA1,  3);
            STEP(H, d, a, b, c, GET(10) + 0x6ED9EBA1,  9);
            STEP(H, c, d, a, b, GET( 6) + 0x6ED9EBA1, 11);
            STEP(H, b, c, d, a, GET(14) + 0x6ED9EBA1, 15);

            STEP(H, a, b, c, d, GET( 1) + 0x6ED9EBA1,  3);
            STEP(H, d, a, b, c, GET( 9) + 0x6ED9EBA1,  9);
            STEP(H, c, d, a, b, GET( 5) + 0x6ED9EBA1, 11);
            STEP(H, b, c, d, a, GET(13) + 0x6ED9EBA1, 15);

            STEP(H, a, b, c, d, GET( 3) + 0x6ED9EBA1,  3);
            STEP(H, d, a, b, c, GET(11) + 0x6ED9EBA1,  9);
            STEP(H, c, d, a, b, GET( 7) + 0x6ED9EBA1, 11);
            STEP(H, b, c, d, a, GET(15) + 0x6ED9EBA1, 15);

            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;
}

static void md4_init(struct md4_context *ctx)
{
      ctx->a = 0x67452301;
      ctx->b = 0xefcdab89;
      ctx->c = 0x98badcfe;
      ctx->d = 0x10325476;

      ctx->lo = 0;
      ctx->hi = 0;
}

static void md4_update(struct md4_context *ctx, const unsigned char *data, size_t size)
{
      /* @UNSAFE */
      quint32 saved_lo;
      unsigned long used, free;

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

      used = saved_lo & 0x3f;

      if (used) {
            free = 64 - used;

            if (size < free) {
                  memcpy(&ctx->buffer[used], data, size);
                  return;
            }

            memcpy(&ctx->buffer[used], data, free);
            data = (const unsigned char *) data + free;
            size -= free;
            body(ctx, ctx->buffer, 64);
      }

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

      memcpy(ctx->buffer, data, size);
}

static void md4_final(struct md4_context *ctx, unsigned char result[MD4_RESULTLEN])
{
      /* @UNSAFE */
      unsigned long used, free;

      used = ctx->lo & 0x3f;

      ctx->buffer[used++] = 0x80;

      free = 64 - used;

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

      memset(&ctx->buffer[used], 0, free - 8);

      ctx->lo <<= 3;
      ctx->buffer[56] = ctx->lo;
      ctx->buffer[57] = ctx->lo >> 8;
      ctx->buffer[58] = ctx->lo >> 16;
      ctx->buffer[59] = ctx->lo >> 24;
      ctx->buffer[60] = 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] = ctx->a;
      result[1] = ctx->a >> 8;
      result[2] = ctx->a >> 16;
      result[3] = ctx->a >> 24;
      result[4] = ctx->b;
      result[5] = ctx->b >> 8;
      result[6] = ctx->b >> 16;
      result[7] = ctx->b >> 24;
      result[8] = ctx->c;
      result[9] = ctx->c >> 8;
      result[10] = ctx->c >> 16;
      result[11] = ctx->c >> 24;
      result[12] = ctx->d;
      result[13] = ctx->d >> 8;
      result[14] = ctx->d >> 16;
      result[15] = ctx->d >> 24;

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

#undef F
#undef G
#undef H

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