// Copyright 2010-2016 The OpenSSL Project Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include <openssl/base.h>

#include <string.h>

#include <openssl/mem.h>

#include "../../internal.h"
#include "../aes/internal.h"
#include "internal.h"


using namespace bssl;

// kSizeTWithoutLower4Bits is a mask that can be used to zero the lower four
// bits of a |size_t|.
static const size_t kSizeTWithoutLower4Bits = (size_t) -16;


#define GCM_MUL(key, ctx, Xi) bssl::gcm_gmult_nohw((ctx)->Xi, (key)->Htable)
#define GHASH(key, ctx, in, len) \
  gcm_ghash_nohw((ctx)->Xi, (key)->Htable, in, len)
// GHASH_CHUNK is "stride parameter" missioned to mitigate cache
// trashing effect. In other words idea is to hash data while it's
// still in L1 cache after encryption pass...
#define GHASH_CHUNK (3 * 1024)

#if defined(GHASH_ASM_X86_64) || defined(GHASH_ASM_X86)
static void gcm_reduce_1bit(u128 *V) {
  if (sizeof(crypto_word_t) == 8) {
    uint64_t T = UINT64_C(0xe100000000000000) & (0 - (V->hi & 1));
    V->hi = (V->lo << 63) | (V->hi >> 1);
    V->lo = (V->lo >> 1) ^ T;
  } else {
    uint32_t T = 0xe1000000U & (0 - (uint32_t)(V->hi & 1));
    V->hi = (V->lo << 63) | (V->hi >> 1);
    V->lo = (V->lo >> 1) ^ ((uint64_t)T << 32);
  }
}

void bssl::gcm_init_ssse3(u128 Htable[16], const uint64_t H[2]) {
  Htable[0].hi = 0;
  Htable[0].lo = 0;
  u128 V;
  V.hi = H[1];
  V.lo = H[0];

  Htable[8] = V;
  gcm_reduce_1bit(&V);
  Htable[4] = V;
  gcm_reduce_1bit(&V);
  Htable[2] = V;
  gcm_reduce_1bit(&V);
  Htable[1] = V;
  Htable[3].hi = V.hi ^ Htable[2].hi, Htable[3].lo = V.lo ^ Htable[2].lo;
  V = Htable[4];
  Htable[5].hi = V.hi ^ Htable[1].hi, Htable[5].lo = V.lo ^ Htable[1].lo;
  Htable[6].hi = V.hi ^ Htable[2].hi, Htable[6].lo = V.lo ^ Htable[2].lo;
  Htable[7].hi = V.hi ^ Htable[3].hi, Htable[7].lo = V.lo ^ Htable[3].lo;
  V = Htable[8];
  Htable[9].hi = V.hi ^ Htable[1].hi, Htable[9].lo = V.lo ^ Htable[1].lo;
  Htable[10].hi = V.hi ^ Htable[2].hi, Htable[10].lo = V.lo ^ Htable[2].lo;
  Htable[11].hi = V.hi ^ Htable[3].hi, Htable[11].lo = V.lo ^ Htable[3].lo;
  Htable[12].hi = V.hi ^ Htable[4].hi, Htable[12].lo = V.lo ^ Htable[4].lo;
  Htable[13].hi = V.hi ^ Htable[5].hi, Htable[13].lo = V.lo ^ Htable[5].lo;
  Htable[14].hi = V.hi ^ Htable[6].hi, Htable[14].lo = V.lo ^ Htable[6].lo;
  Htable[15].hi = V.hi ^ Htable[7].hi, Htable[15].lo = V.lo ^ Htable[7].lo;

  // Treat |Htable| as a 16x16 byte table and transpose it. Thus, Htable[i]
  // contains the i'th byte of j*H for all j.
  uint8_t *Hbytes = (uint8_t *)Htable;
  for (int i = 0; i < 16; i++) {
    for (int j = 0; j < i; j++) {
      uint8_t tmp = Hbytes[16*i + j];
      Hbytes[16*i + j] = Hbytes[16*j + i];
      Hbytes[16*j + i] = tmp;
    }
  }
}
#endif  // GHASH_ASM_X86_64 || GHASH_ASM_X86

#ifdef GCM_FUNCREF
#undef GCM_MUL
#define GCM_MUL(key, ctx, Xi) (*gcm_gmult_p)((ctx)->Xi, (key)->Htable)
#undef GHASH
#define GHASH(key, ctx, in, len) \
  (*gcm_ghash_p)((ctx)->Xi, (key)->Htable, in, len)
#endif  // GCM_FUNCREF

#if defined(HW_GCM) && defined(OPENSSL_X86_64)
static size_t hw_gcm_encrypt(const uint8_t *in, uint8_t *out, size_t len,
                             const AES_KEY *key, uint8_t ivec[16],
                             uint8_t Xi[16], const u128 Htable[16],
                             enum gcm_impl_t impl) {
  switch (impl) {
    case gcm_x86_vaes_avx2:
      len &= kSizeTWithoutLower4Bits;
      aes_gcm_enc_update_vaes_avx2(in, out, len, key, ivec, Htable, Xi);
      CRYPTO_store_u32_be(&ivec[12], CRYPTO_load_u32_be(&ivec[12]) + len / 16);
      return len;
    case gcm_x86_vaes_avx512:
      len &= kSizeTWithoutLower4Bits;
      aes_gcm_enc_update_vaes_avx512(in, out, len, key, ivec, Htable, Xi);
      CRYPTO_store_u32_be(&ivec[12], CRYPTO_load_u32_be(&ivec[12]) + len / 16);
      return len;
    default:
      return aesni_gcm_encrypt(in, out, len, key, ivec, Htable, Xi);
  }
}

static size_t hw_gcm_decrypt(const uint8_t *in, uint8_t *out, size_t len,
                             const AES_KEY *key, uint8_t ivec[16],
                             uint8_t Xi[16], const u128 Htable[16],
                             enum gcm_impl_t impl) {
  switch (impl) {
    case gcm_x86_vaes_avx2:
      len &= kSizeTWithoutLower4Bits;
      aes_gcm_dec_update_vaes_avx2(in, out, len, key, ivec, Htable, Xi);
      CRYPTO_store_u32_be(&ivec[12], CRYPTO_load_u32_be(&ivec[12]) + len / 16);
      return len;
    case gcm_x86_vaes_avx512:
      len &= kSizeTWithoutLower4Bits;
      aes_gcm_dec_update_vaes_avx512(in, out, len, key, ivec, Htable, Xi);
      CRYPTO_store_u32_be(&ivec[12], CRYPTO_load_u32_be(&ivec[12]) + len / 16);
      return len;
    default:
      return aesni_gcm_decrypt(in, out, len, key, ivec, Htable, Xi);
  }
}
#endif  // HW_GCM && X86_64

#if defined(HW_GCM) && defined(OPENSSL_AARCH64)

static size_t hw_gcm_encrypt(const uint8_t *in, uint8_t *out, size_t len,
                             const AES_KEY *key, uint8_t ivec[16],
                             uint8_t Xi[16], const u128 Htable[16],
                             enum gcm_impl_t impl) {
  const size_t len_blocks = len & kSizeTWithoutLower4Bits;
  if (!len_blocks) {
    return 0;
  }
  if (impl == gcm_arm64_aes_eor3) {
    aes_gcm_enc_kernel_eor3(in, len_blocks * 8, out, Xi, ivec, key, Htable);
    return len_blocks;
  }
  aes_gcm_enc_kernel(in, len_blocks * 8, out, Xi, ivec, key, Htable);
  return len_blocks;
}

static size_t hw_gcm_decrypt(const uint8_t *in, uint8_t *out, size_t len,
                             const AES_KEY *key, uint8_t ivec[16],
                             uint8_t Xi[16], const u128 Htable[16],
                             enum gcm_impl_t impl) {
  const size_t len_blocks = len & kSizeTWithoutLower4Bits;
  if (!len_blocks) {
    return 0;
  }
  if (impl == gcm_arm64_aes_eor3) {
    aes_gcm_dec_kernel_eor3(in, len_blocks * 8, out, Xi, ivec, key, Htable);
    return len_blocks;
  }
  aes_gcm_dec_kernel(in, len_blocks * 8, out, Xi, ivec, key, Htable);
  return len_blocks;
}

#endif  // HW_GCM && AARCH64

void bssl::CRYPTO_ghash_init(gmult_func *out_mult, ghash_func *out_hash,
                             u128 out_table[16], const uint8_t gcm_key[16]) {
  // H is passed to |gcm_init_*| as a pair of byte-swapped, 64-bit values.
  uint64_t H[2] = {CRYPTO_load_u64_be(gcm_key),
                   CRYPTO_load_u64_be(gcm_key + 8)};

#if defined(GHASH_ASM_X86_64)
  if (crypto_gcm_clmul_enabled()) {
    if (CRYPTO_is_VPCLMULQDQ_capable() && CRYPTO_is_AVX2_capable()) {
      if (CRYPTO_is_AVX512BW_capable() && CRYPTO_is_AVX512VL_capable() &&
          CRYPTO_is_BMI2_capable() && !CRYPTO_cpu_avoid_zmm_registers()) {
        gcm_init_vpclmulqdq_avx512(out_table, H);
        *out_mult = gcm_gmult_vpclmulqdq_avx512;
        *out_hash = gcm_ghash_vpclmulqdq_avx512;
        return;
      }
      gcm_init_vpclmulqdq_avx2(out_table, H);
      *out_mult = gcm_gmult_vpclmulqdq_avx2;
      *out_hash = gcm_ghash_vpclmulqdq_avx2;
      return;
    }
    if (CRYPTO_is_AVX_capable() && CRYPTO_is_MOVBE_capable()) {
      gcm_init_avx(out_table, H);
      *out_mult = gcm_gmult_avx;
      *out_hash = gcm_ghash_avx;
      return;
    }
    gcm_init_clmul(out_table, H);
    *out_mult = gcm_gmult_clmul;
    *out_hash = gcm_ghash_clmul;
    return;
  }
  if (CRYPTO_is_SSSE3_capable()) {
    gcm_init_ssse3(out_table, H);
    *out_mult = gcm_gmult_ssse3;
    *out_hash = gcm_ghash_ssse3;
    return;
  }
#elif defined(GHASH_ASM_X86)
  if (crypto_gcm_clmul_enabled()) {
    gcm_init_clmul(out_table, H);
    *out_mult = gcm_gmult_clmul;
    *out_hash = gcm_ghash_clmul;
    return;
  }
  if (CRYPTO_is_SSSE3_capable()) {
    gcm_init_ssse3(out_table, H);
    *out_mult = gcm_gmult_ssse3;
    *out_hash = gcm_ghash_ssse3;
    return;
  }
#elif defined(GHASH_ASM_ARM)
  if (gcm_pmull_capable()) {
    gcm_init_v8(out_table, H);
    *out_mult = gcm_gmult_v8;
    *out_hash = gcm_ghash_v8;
    return;
  }

  if (gcm_neon_capable()) {
    gcm_init_neon(out_table, H);
    *out_mult = gcm_gmult_neon;
    *out_hash = gcm_ghash_neon;
    return;
  }
#endif

  gcm_init_nohw(out_table, H);
  *out_mult = gcm_gmult_nohw;
  *out_hash = gcm_ghash_nohw;
}

void bssl::CRYPTO_gcm128_init_aes_key(GCM128_KEY *gcm_key, const uint8_t *key,
                                      size_t key_bytes) {
  switch (key_bytes) {
    case 16:
      boringssl_fips_inc_counter(fips_counter_evp_aes_128_gcm);
      break;

    case 32:
      boringssl_fips_inc_counter(fips_counter_evp_aes_256_gcm);
      break;
  }

  OPENSSL_memset(gcm_key, 0, sizeof(*gcm_key));
  int is_hwaes;
  gcm_key->ctr = aes_ctr_set_key(&gcm_key->aes, &is_hwaes, &gcm_key->block, key,
                                 key_bytes);

  uint8_t ghash_key[16];
  OPENSSL_memset(ghash_key, 0, sizeof(ghash_key));
  gcm_key->block(ghash_key, ghash_key, &gcm_key->aes);

  CRYPTO_ghash_init(&gcm_key->gmult, &gcm_key->ghash, gcm_key->Htable,
                    ghash_key);

#if !defined(OPENSSL_NO_ASM)
#if defined(OPENSSL_X86_64)
  if (gcm_key->ghash == gcm_ghash_vpclmulqdq_avx512 &&
      CRYPTO_is_VAES_capable()) {
    gcm_key->impl = gcm_x86_vaes_avx512;
  } else if (gcm_key->ghash == gcm_ghash_vpclmulqdq_avx2 &&
             CRYPTO_is_VAES_capable()) {
    gcm_key->impl = gcm_x86_vaes_avx2;
  } else if (gcm_key->ghash == gcm_ghash_avx && is_hwaes) {
    gcm_key->impl = gcm_x86_aesni;
  }
#elif defined(OPENSSL_AARCH64)
  if (gcm_eor3_capable() && is_hwaes) {
    gcm_key->impl = gcm_arm64_aes_eor3;
  } else if (gcm_pmull_capable() && is_hwaes) {
    gcm_key->impl = gcm_arm64_aes;
  }
#endif
#endif
}

void bssl::CRYPTO_gcm128_init_ctx(const GCM128_KEY *key, GCM128_CONTEXT *ctx,
                                  const uint8_t *iv, size_t iv_len) {
#ifdef GCM_FUNCREF
  void (*gcm_gmult_p)(uint8_t Xi[16], const u128 Htable[16]) = key->gmult;
#endif

  OPENSSL_memset(&ctx->Yi, 0, sizeof(ctx->Yi));
  OPENSSL_memset(&ctx->Xi, 0, sizeof(ctx->Xi));
  ctx->len.aad = 0;
  ctx->len.msg = 0;
  ctx->ares = 0;
  ctx->mres = 0;

  uint32_t ctr;
  if (iv_len == 12) {
    OPENSSL_memcpy(ctx->Yi, iv, 12);
    ctx->Yi[15] = 1;
    ctr = 1;
  } else {
    uint64_t len0 = iv_len;

    while (iv_len >= 16) {
      CRYPTO_xor16(ctx->Yi, ctx->Yi, iv);
      GCM_MUL(key, ctx, Yi);
      iv += 16;
      iv_len -= 16;
    }
    if (iv_len) {
      for (size_t i = 0; i < iv_len; ++i) {
        ctx->Yi[i] ^= iv[i];
      }
      GCM_MUL(key, ctx, Yi);
    }

    uint8_t len_block[16];
    OPENSSL_memset(len_block, 0, 8);
    CRYPTO_store_u64_be(len_block + 8, len0 << 3);
    CRYPTO_xor16(ctx->Yi, ctx->Yi, len_block);

    GCM_MUL(key, ctx, Yi);
    ctr = CRYPTO_load_u32_be(ctx->Yi + 12);
  }

  key->block(ctx->Yi, ctx->EK0, &key->aes);
  ++ctr;
  CRYPTO_store_u32_be(ctx->Yi + 12, ctr);
}

int bssl::CRYPTO_gcm128_aad(const GCM128_KEY *key, GCM128_CONTEXT *ctx,
                            const uint8_t *aad, size_t aad_len) {
#ifdef GCM_FUNCREF
  void (*gcm_gmult_p)(uint8_t Xi[16], const u128 Htable[16]) = key->gmult;
  void (*gcm_ghash_p)(uint8_t Xi[16], const u128 Htable[16], const uint8_t *inp,
                      size_t len) = key->ghash;
#endif

  if (ctx->len.msg != 0) {
    // The caller must have finished the AAD before providing other input.
    return 0;
  }

  uint64_t alen = ctx->len.aad + aad_len;
  if (alen > (UINT64_C(1) << 61) || (sizeof(aad_len) == 8 && alen < aad_len)) {
    return 0;
  }
  ctx->len.aad = alen;

  unsigned n = ctx->ares;
  if (n) {
    while (n && aad_len) {
      ctx->Xi[n] ^= *(aad++);
      --aad_len;
      n = (n + 1) % 16;
    }
    if (n == 0) {
      GCM_MUL(key, ctx, Xi);
    } else {
      ctx->ares = n;
      return 1;
    }
  }

  // Process a whole number of blocks.
  size_t len_blocks = aad_len & kSizeTWithoutLower4Bits;
  if (len_blocks != 0) {
    GHASH(key, ctx, aad, len_blocks);
    aad += len_blocks;
    aad_len -= len_blocks;
  }

  // Process the remainder.
  if (aad_len != 0) {
    n = (unsigned int)aad_len;
    for (size_t i = 0; i < aad_len; ++i) {
      ctx->Xi[i] ^= aad[i];
    }
  }

  ctx->ares = n;
  return 1;
}

int bssl::CRYPTO_gcm128_encrypt(const GCM128_KEY *key, GCM128_CONTEXT *ctx,
                                const uint8_t *in, uint8_t *out, size_t len) {
#ifdef GCM_FUNCREF
  void (*gcm_gmult_p)(uint8_t Xi[16], const u128 Htable[16]) = key->gmult;
  void (*gcm_ghash_p)(uint8_t Xi[16], const u128 Htable[16], const uint8_t *inp,
                      size_t len) = key->ghash;
#endif

  uint64_t mlen = ctx->len.msg + len;
  if (mlen > ((UINT64_C(1) << 36) - 32) ||
      (sizeof(len) == 8 && mlen < len)) {
    return 0;
  }
  ctx->len.msg = mlen;

  if (ctx->ares) {
    // First call to encrypt finalizes GHASH(AAD)
    GCM_MUL(key, ctx, Xi);
    ctx->ares = 0;
  }

  unsigned n = ctx->mres;
  if (n) {
    while (n && len) {
      ctx->Xi[n] ^= *(out++) = *(in++) ^ ctx->EKi[n];
      --len;
      n = (n + 1) % 16;
    }
    if (n == 0) {
      GCM_MUL(key, ctx, Xi);
    } else {
      ctx->mres = n;
      return 1;
    }
  }

#if defined(HW_GCM)
  if (key->impl != gcm_separate && len > 0) {
    // |hw_gcm_encrypt| may not process all the input given to it. It may
    // not process *any* of its input if it is deemed too small.
    size_t bulk = hw_gcm_encrypt(in, out, len, &key->aes, ctx->Yi, ctx->Xi,
                                 key->Htable, key->impl);
    in += bulk;
    out += bulk;
    len -= bulk;
  }
#endif

  uint32_t ctr = CRYPTO_load_u32_be(ctx->Yi + 12);
  ctr128_f stream = key->ctr;
  while (len >= GHASH_CHUNK) {
    (*stream)(in, out, GHASH_CHUNK / 16, &key->aes, ctx->Yi);
    ctr += GHASH_CHUNK / 16;
    CRYPTO_store_u32_be(ctx->Yi + 12, ctr);
    GHASH(key, ctx, out, GHASH_CHUNK);
    out += GHASH_CHUNK;
    in += GHASH_CHUNK;
    len -= GHASH_CHUNK;
  }

  size_t len_blocks = len & kSizeTWithoutLower4Bits;
  if (len_blocks != 0) {
    size_t j = len_blocks / 16;
    (*stream)(in, out, j, &key->aes, ctx->Yi);
    ctr += (uint32_t)j;
    CRYPTO_store_u32_be(ctx->Yi + 12, ctr);
    in += len_blocks;
    len -= len_blocks;
    GHASH(key, ctx, out, len_blocks);
    out += len_blocks;
  }

  if (len) {
    key->block(ctx->Yi, ctx->EKi, &key->aes);
    ++ctr;
    CRYPTO_store_u32_be(ctx->Yi + 12, ctr);
    while (len--) {
      ctx->Xi[n] ^= out[n] = in[n] ^ ctx->EKi[n];
      ++n;
    }
  }

  ctx->mres = n;
  return 1;
}

int bssl::CRYPTO_gcm128_decrypt(const GCM128_KEY *key, GCM128_CONTEXT *ctx,
                                const uint8_t *in, uint8_t *out, size_t len) {
#ifdef GCM_FUNCREF
  void (*gcm_gmult_p)(uint8_t Xi[16], const u128 Htable[16]) = key->gmult;
  void (*gcm_ghash_p)(uint8_t Xi[16], const u128 Htable[16], const uint8_t *inp,
                      size_t len) = key->ghash;
#endif

  uint64_t mlen = ctx->len.msg + len;
  if (mlen > ((UINT64_C(1) << 36) - 32) ||
      (sizeof(len) == 8 && mlen < len)) {
    return 0;
  }
  ctx->len.msg = mlen;

  if (ctx->ares) {
    // First call to decrypt finalizes GHASH(AAD)
    GCM_MUL(key, ctx, Xi);
    ctx->ares = 0;
  }

  unsigned n = ctx->mres;
  if (n) {
    while (n && len) {
      uint8_t c = *(in++);
      *(out++) = c ^ ctx->EKi[n];
      ctx->Xi[n] ^= c;
      --len;
      n = (n + 1) % 16;
    }
    if (n == 0) {
      GCM_MUL(key, ctx, Xi);
    } else {
      ctx->mres = n;
      return 1;
    }
  }

#if defined(HW_GCM)
  if (key->impl != gcm_separate && len > 0) {
    // |hw_gcm_decrypt| may not process all the input given to it. It may
    // not process *any* of its input if it is deemed too small.
    size_t bulk = hw_gcm_decrypt(in, out, len, &key->aes, ctx->Yi, ctx->Xi,
                                 key->Htable, key->impl);
    in += bulk;
    out += bulk;
    len -= bulk;
  }
#endif

  uint32_t ctr = CRYPTO_load_u32_be(ctx->Yi + 12);
  ctr128_f stream = key->ctr;
  while (len >= GHASH_CHUNK) {
    GHASH(key, ctx, in, GHASH_CHUNK);
    (*stream)(in, out, GHASH_CHUNK / 16, &key->aes, ctx->Yi);
    ctr += GHASH_CHUNK / 16;
    CRYPTO_store_u32_be(ctx->Yi + 12, ctr);
    out += GHASH_CHUNK;
    in += GHASH_CHUNK;
    len -= GHASH_CHUNK;
  }

  size_t len_blocks = len & kSizeTWithoutLower4Bits;
  if (len_blocks != 0) {
    size_t j = len_blocks / 16;
    GHASH(key, ctx, in, len_blocks);
    (*stream)(in, out, j, &key->aes, ctx->Yi);
    ctr += (uint32_t)j;
    CRYPTO_store_u32_be(ctx->Yi + 12, ctr);
    out += len_blocks;
    in += len_blocks;
    len -= len_blocks;
  }

  if (len) {
    key->block(ctx->Yi, ctx->EKi, &key->aes);
    ++ctr;
    CRYPTO_store_u32_be(ctx->Yi + 12, ctr);
    while (len--) {
      uint8_t c = in[n];
      ctx->Xi[n] ^= c;
      out[n] = c ^ ctx->EKi[n];
      ++n;
    }
  }

  ctx->mres = n;
  return 1;
}

int bssl::CRYPTO_gcm128_finish(const GCM128_KEY *key, GCM128_CONTEXT *ctx,
                               const uint8_t *tag, size_t len) {
#ifdef GCM_FUNCREF
  void (*gcm_gmult_p)(uint8_t Xi[16], const u128 Htable[16]) = key->gmult;
#endif

  if (ctx->mres || ctx->ares) {
    GCM_MUL(key, ctx, Xi);
  }

  uint8_t len_block[16];
  CRYPTO_store_u64_be(len_block, ctx->len.aad << 3);
  CRYPTO_store_u64_be(len_block + 8, ctx->len.msg << 3);
  CRYPTO_xor16(ctx->Xi, ctx->Xi, len_block);
  GCM_MUL(key, ctx, Xi);
  CRYPTO_xor16(ctx->Xi, ctx->Xi, ctx->EK0);

  if (tag && len <= sizeof(ctx->Xi)) {
    return CRYPTO_memcmp(ctx->Xi, tag, len) == 0;
  } else {
    return 0;
  }
}

void bssl::CRYPTO_gcm128_tag(const GCM128_KEY *key, GCM128_CONTEXT *ctx,
                             uint8_t *tag, size_t len) {
  CRYPTO_gcm128_finish(key, ctx, nullptr, 0);
  OPENSSL_memcpy(tag, ctx->Xi, len <= sizeof(ctx->Xi) ? len : sizeof(ctx->Xi));
}

#if defined(OPENSSL_X86) || defined(OPENSSL_X86_64)
int bssl::crypto_gcm_clmul_enabled() {
#if defined(GHASH_ASM_X86) || defined(GHASH_ASM_X86_64)
  return CRYPTO_is_PCLMUL_capable() && CRYPTO_is_SSSE3_capable();
#else
  return 0;
#endif
}
#endif