// Copyright 2008-2016 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 <assert.h>

#include <string.h>

#include "internal.h"

using namespace bssl;

static_assert(16 % sizeof(size_t) == 0, "block cannot be divided into size_t");

void bssl::CRYPTO_ofb128_encrypt(const uint8_t *in, uint8_t *out, size_t len,

                                 const AES_KEY *key, uint8_t ivec[16],

                                 unsigned *num, block128_f block) {

  assert(key != nullptr && ivec != nullptr && num != nullptr);

  assert(len == 0 || (in != nullptr && out != nullptr));

  unsigned n = *num;

  while (n && len) {

    *(out++) = *(in++) ^ ivec[n];

    --len;

    n = (n + 1) % 16;

  }

  while (len >= 16) {

    (*block)(ivec, ivec, key);

    CRYPTO_xor16(out, in, ivec);

    len -= 16;

    out += 16;

    in += 16;

    n = 0;

  }

  if (len) {

    (*block)(ivec, ivec, key);

    while (len--) {

      out[n] = in[n] ^ ivec[n];

      ++n;

    }

  }

  *num = n;

}