/****************************************************************************
 * apps/fsutils/passwd/passwd_encrypt.c
 *
 *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * 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. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS 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
 * COPYRIGHT OWNER OR 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.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>

#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>

#include <nuttx/crypto/tea.h>

#include "passwd.h"

/****************************************************************************
 * Private Data
 ****************************************************************************/
/* This should be better protected */

static uint32_t g_tea_key[4] =
{
  CONFIG_FSUTILS_PASSWD_KEY1,
  CONFIG_FSUTILS_PASSWD_KEY2,
  CONFIG_FSUTILS_PASSWD_KEY3,
  CONFIG_FSUTILS_PASSWD_KEY4
};

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: passwd_encrypt
 *
 * Description: 
 *   Encrypt a password.  Currently uses the Tiny Encryption Algorithm.
 *
 * Input Parameters:
 *   password -- The password string to be encrypted
 *
 * Returned Value:
 *   Zero (OK) is returned on success; a negated errno value is returned on
 *   failure.
 *
 ****************************************************************************/

int passwd_encrypt(FAR const char *password, char encrypted[MAX_ENCRYPTED + 1])
{
  union
  {
    char     b[8];
    uint32_t l[2];
  } value;

  FAR const char *src;
  FAR char *dest;
  int remaining;
  int converted;
  int enclen;
  int gulpsize;
  int i;

  /* How long is the password? */

  remaining = strlen(password);
  if (remaining > MAX_PASSWORD)
    {
      return -E2BIG;
    }

  /* Convert the password in 8-byte TEA cycles */

  src          = password;
  encrypted[0] = '\0';
  enclen       = 0;

  for (converted = 0; converted < remaining; converted += 8)
    {
      /* Copy bytes */

      gulpsize = 8;
      if (gulpsize > remaining)
        {
          gulpsize = remaining;
        }

      dest = value.b;
      for (i = 0; i < gulpsize; i++)
        {
          *dest++ = *src++;
        }

      /* Pad with spaces if necessary */

      for (; i < 8; i++)
        {
          *dest++ = ' ';
        }

      /* Perform the conversion for this cycle */

      tea_encrypt(value.l, g_tea_key);

      /* Generate the output from this cycle */

      enclen += snprintf(&encrypted[enclen],
                         MAX_ENCRYPTED - enclen,
                         "%08lx%08lx",
                         (unsigned long)value.l[0],
                         (unsigned long)value.l[1]);
    }

  return OK;
}