gra-projekt/Implementierung/src/md2_impls/md2_1.c

#include "../../lib/md2_impls/md2_1.h"

#include <immintrin.h>

#include "../../lib/md2_impls/md2_common.h"

static uint8_t PADDING[17][16] = {
    {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
    {1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
    {2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
    {3, 3, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
    {4, 4, 4, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
    {5, 5, 5, 5, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
    {6, 6, 6, 6, 6, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
    {7, 7, 7, 7, 7, 7, 7, 0, 0, 0, 0, 0, 0, 0, 0, 0},
    {8, 8, 8, 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 0, 0, 0},
    {9, 9, 9, 9, 9, 9, 9, 9, 9, 0, 0, 0, 0, 0, 0, 0},
    {10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 0, 0, 0, 0, 0, 0},
    {11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 0, 0, 0, 0, 0},
    {12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 0, 0, 0, 0},
    {13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 0, 0, 0},
    {14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 0, 0},
    {15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 0},
    {16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16}};

void md2_hash_1(size_t len, const uint8_t buf[len], uint8_t out[16]) {
  // === step 1 ===
  int paddingNeeded = 16 - (len & 15);
  len += paddingNeeded;

  uint8_t *newBuf = aligned_alloc(16, sizeof(uint8_t) * (len + 16));
  if (newBuf == NULL) {
    return;
  }

  for (size_t i = 0; i < 16; i++) {
    newBuf[len + i] = 0;
  }

  memcpy(newBuf, buf, len - paddingNeeded);

  memcpy(newBuf + len - paddingNeeded, PADDING + paddingNeeded, paddingNeeded);

  // === step 2 ===
  md2_checksum(len, newBuf);

  // === step 3 ===
  uint8_t *messageDigestBuf = aligned_alloc(16, sizeof(uint8_t) * 48);
  if (messageDigestBuf == NULL) {
    return;
  }

  for (size_t i = 0; i < 48; i++) {
    messageDigestBuf[i] = 0;
  }

  // === step 4 ===
  __m128i vx;
  __m128i vy;
  for (size_t i = 0; i <= (len + 16) / 16 - 1; i++) {
    FIRST_LOOP_START_MARK
    // first loop replaced by 5 SIMD-Operations
    vx = _mm_load_si128((__m128i *)(newBuf + i * 16));
    _mm_store_si128((__m128i *)(messageDigestBuf + 16), vx);
    vy = _mm_load_si128((__m128i *)(messageDigestBuf));
    vy = _mm_xor_si128(vy, vx);
    _mm_store_si128((__m128i *)(messageDigestBuf + 32), vy);
    FIRST_LOOP_END_MARK

    md2_second_loop(messageDigestBuf);
  }

  END_MARK
  memcpy(out, messageDigestBuf, 16);

  free(messageDigestBuf);
  free(newBuf);
}