/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL

 * project 1999.

 */

/* ====================================================================

 * Copyright (c) 1999 The OpenSSL Project.  All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer. 

 *

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in

 *    the documentation and/or other materials provided with the

 *    distribution.

 *

 * 3. All advertising materials mentioning features or use of this

 *    software must display the following acknowledgment:

 *    "This product includes software developed by the OpenSSL Project

 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"

 *

 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to

 *    endorse or promote products derived from this software without

 *    prior written permission. For written permission, please contact

 *    licensing@OpenSSL.org.

 *

 * 5. Products derived from this software may not be called "OpenSSL"

 *    nor may "OpenSSL" appear in their names without prior written

 *    permission of the OpenSSL Project.

 *

 * 6. Redistributions of any form whatsoever must retain the following

 *    acknowledgment:

 *    "This product includes software developed by the OpenSSL Project

 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"

 *

 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY

 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR

 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,

 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED

 * OF THE POSSIBILITY OF SUCH DAMAGE.

 * ====================================================================

 *

 * This product includes cryptographic software written by Eric Young

 * (eay@cryptsoft.com).  This product includes software written by Tim

 * Hudson (tjh@cryptsoft.com). */

#include <openssl/evp.h>

#include <string.h>

#include <openssl/hmac.h>

#include "../internal.h"

int PKCS5_PBKDF2_HMAC(const char *password, size_t password_len,

                      const uint8_t *salt, size_t salt_len, unsigned iterations,

                      const EVP_MD *digest, size_t key_len, uint8_t *out_key) {

  // See RFC 8018, section 5.2.

  int ret = 0;

  size_t md_len = EVP_MD_size(digest);

  uint32_t i = 1;

  HMAC_CTX hctx;

  HMAC_CTX_init(&hctx);

  if (!HMAC_Init_ex(&hctx, password, password_len, digest, NULL)) {

    goto err;

  }

  while (key_len > 0) {

    size_t todo = md_len;

    if (todo > key_len) {

      todo = key_len;

    }

    uint8_t i_buf[4];

    i_buf[0] = (uint8_t)((i >> 24) & 0xff);

    i_buf[1] = (uint8_t)((i >> 16) & 0xff);

    i_buf[2] = (uint8_t)((i >> 8) & 0xff);

    i_buf[3] = (uint8_t)(i & 0xff);

    // Compute U_1.

    uint8_t digest_tmp[EVP_MAX_MD_SIZE];

    if (!HMAC_Init_ex(&hctx, NULL, 0, NULL, NULL) ||

        !HMAC_Update(&hctx, salt, salt_len) ||

        !HMAC_Update(&hctx, i_buf, 4) ||

        !HMAC_Final(&hctx, digest_tmp, NULL)) {

      goto err;

    }

    OPENSSL_memcpy(out_key, digest_tmp, todo);

    for (unsigned j = 1; j < iterations; j++) {

      // Compute the remaining U_* values and XOR.

      if (!HMAC_Init_ex(&hctx, NULL, 0, NULL, NULL) ||

          !HMAC_Update(&hctx, digest_tmp, md_len) ||

          !HMAC_Final(&hctx, digest_tmp, NULL)) {

        goto err;

      }

      for (size_t k = 0; k < todo; k++) {

        out_key[k] ^= digest_tmp[k];

      }

    }

    key_len -= todo;

    out_key += todo;

    i++;

  }

  // RFC 8018 describes iterations (c) as being a "positive integer", so a

  // value of 0 is an error.

  //

  // Unfortunately not all consumers of PKCS5_PBKDF2_HMAC() check their return

  // value, expecting it to succeed and unconditionally using |out_key|.  As a

  // precaution for such callsites in external code, the old behavior of

  // iterations < 1 being treated as iterations == 1 is preserved, but

  // additionally an error result is returned.

  //

  // TODO(eroman): Figure out how to remove this compatibility hack, or change

  // the default to something more sensible like 2048.

  if (iterations == 0) {

    goto err;

  }

  ret = 1;

err:

  HMAC_CTX_cleanup(&hctx);

  return ret;

}

int PKCS5_PBKDF2_HMAC_SHA1(const char *password, size_t password_len,

                           const uint8_t *salt, size_t salt_len,

                           unsigned iterations, size_t key_len,

                           uint8_t *out_key) {

  return PKCS5_PBKDF2_HMAC(password, password_len, salt, salt_len, iterations,

                           EVP_sha1(), key_len, out_key);

}