/*

 * Copyright (C) 2016 Red Hat

 *

 * Author: Nikos Mavrogiannopoulos

 *

 * This file is part of GnuTLS.

 *

 * The GnuTLS is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public License

 * as published by the Free Software Foundation; either version 2.1 of

 * the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with this program.  If not, see <https://www.gnu.org/licenses/>

 *

 */

#include "gnutls_int.h"

#include <datum.h>

#include <global.h>

#include "errors.h"

#include <common.h>

#include <x509.h>

#include <x509_b64.h>

#include "x509_int.h"

#include "pkcs7_int.h"

#include <algorithms.h>

#include <nettle/md5.h>

/* This file includes support for PKCS#8 PBES1 with DES and MD5.

 * We only support decryption for compatibility with other software.

 */

int _gnutls_read_pbkdf1_params(const uint8_t * data, int data_size,

             struct pbkdf2_params *kdf_params,

             struct pbe_enc_params *enc_params)

{

  asn1_node pasn = NULL;

  int len;

  int ret, result;

  memset(kdf_params, 0, sizeof(*kdf_params));

  memset(enc_params, 0, sizeof(*enc_params));

  if ((result =

       asn1_create_element(_gnutls_get_pkix(),

         "PKIX1.pkcs-5-PBE-params",

         &pasn)) != ASN1_SUCCESS) {

    gnutls_assert();

    return _gnutls_asn2err(result);

  }

  /* Decode the parameters.

   */

  result = _asn1_strict_der_decode(&pasn, data, data_size, NULL);

  if (result != ASN1_SUCCESS) {

    gnutls_assert();

    ret = _gnutls_asn2err(result);

    goto error;

  }

  ret =

      _gnutls_x509_read_uint(pasn, "iterationCount",

           &kdf_params->iter_count);

  if (ret < 0) {

    gnutls_assert();

    goto error;

  }

  if (kdf_params->iter_count >= MAX_ITER_COUNT

      || kdf_params->iter_count == 0) {

    ret = gnutls_assert_val(GNUTLS_E_ILLEGAL_PARAMETER);

    goto error;

  }

  len = sizeof(kdf_params->salt);

  result = asn1_read_value(pasn, "salt", kdf_params->salt, &len);

  if (result != ASN1_SUCCESS) {

    gnutls_assert();

    ret = _gnutls_asn2err(result);

    goto error;

  }

  if (len != 8) {

    gnutls_assert();

    ret = GNUTLS_E_ILLEGAL_PARAMETER;

    goto error;

  }

  enc_params->cipher = GNUTLS_CIPHER_DES_CBC;

  ret = 0;

 error:

  asn1_delete_structure2(&pasn, ASN1_DELETE_FLAG_ZEROIZE);

  return ret;

}

static void pbkdf1_md5(const char *password, unsigned password_len,

           const uint8_t salt[8], unsigned iter_count,

           unsigned key_size, uint8_t * key)

{

  struct md5_ctx ctx;

  uint8_t tmp[16];

  unsigned i;

  if (key_size > sizeof(tmp))

    abort();

  for (i = 0; i < iter_count; i++) {

    md5_init(&ctx);

    if (i == 0) {

      md5_update(&ctx, password_len, (uint8_t *) password);

      md5_update(&ctx, 8, salt);

      md5_digest(&ctx, 16, tmp);

    } else {

      md5_update(&ctx, 16, tmp);

      md5_digest(&ctx, 16, tmp);

    }

  }

  memcpy(key, tmp, key_size);

  return;

}

int

_gnutls_decrypt_pbes1_des_md5_data(const char *password,

           unsigned password_len,

           const struct pbkdf2_params *kdf_params,

           const struct pbe_enc_params *enc_params,

           const gnutls_datum_t * encrypted_data,

           gnutls_datum_t * decrypted_data)

{

  int result;

  gnutls_datum_t dkey, d_iv;

  gnutls_cipher_hd_t ch;

  uint8_t key[16];

  const unsigned block_size = 8;

  if (enc_params->cipher != GNUTLS_CIPHER_DES_CBC)

    return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);

  if (encrypted_data->size % block_size != 0)

    return gnutls_assert_val(GNUTLS_E_ILLEGAL_PARAMETER);

  /* generate the key

   */

  pbkdf1_md5(password, password_len, kdf_params->salt,

       kdf_params->iter_count, sizeof(key), key);

  dkey.data = key;

  dkey.size = 8;

  d_iv.data = &key[8];

  d_iv.size = 8;

  result = gnutls_cipher_init(&ch, GNUTLS_CIPHER_DES_CBC, &dkey, &d_iv);

  if (result < 0) {

    _gnutls_switch_fips_state(GNUTLS_FIPS140_OP_ERROR);

    return gnutls_assert_val(result);

  }

  _gnutls_switch_fips_state(GNUTLS_FIPS140_OP_NOT_APPROVED);

  result =

      gnutls_cipher_decrypt(ch, encrypted_data->data,

          encrypted_data->size);

  if (result < 0) {

    gnutls_assert();

    goto error;

  }

  if ((int)encrypted_data->size -

      encrypted_data->data[encrypted_data->size - 1] < 0) {

    gnutls_assert();

    result = GNUTLS_E_ILLEGAL_PARAMETER;

    goto error;

  }

  decrypted_data->data = encrypted_data->data;

  decrypted_data->size =

      encrypted_data->size - encrypted_data->data[encrypted_data->size -

              1];

  result = 0;

 error:

  gnutls_cipher_deinit(ch);

  return result;

}