text: /*
   * Copyright (c) 2013 Jan-Piet Mens <jpmens()gmail.com>
   * 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. Neither the name of mosquitto 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.
   */
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  #include <getopt.h>
  #include <openssl/evp.h>
  #include <openssl/rand.h>
  #include "base64.h"
  
  #define KEY_LENGTH      24
  #define SEPARATOR       "$"
  #define SALTLEN 12
  
  #define USAGE() fprintf(stderr, "Usage: %s [-i iterations]\n", progname)
  
  int main(int argc, char **argv)
  {
          int iterations = 901, rc, saltlen, blen;
  	unsigned char	saltbytes[SALTLEN];
  	char *salt, *b64;
  	unsigned char key[128];
  	char *pw1, *pw2, *password;
  	char *progname = argv[0];
  	int c;
  
  	while ((c = getopt(argc, argv, "i:")) != EOF) {
  		switch (c) {
  			case 'i':
  				iterations = atoi(optarg);
  				break;
  			default:
  				exit(USAGE());
  		}
  	}
  
  	argc -= optind - 1;
  	argv += optind - 1;
  
  	if (argc != 1) {
  		exit(USAGE());
  	}
  
  	pw1 = strdup(getpass("Enter password: "));
  	pw2 = getpass("Re-enter same password: ");
  
  	if (strcmp(pw1, pw2) != 0) {
  		fprintf(stderr, "Passwords don't match!\n");
  		return (1);
  	}
  
  	password = pw1;
  
  	rc = RAND_bytes(saltbytes, SALTLEN);
  	if (rc == 0) {
  		fprintf(stderr, "Cannot get random bytes for salt!\n");
  		return 2;
  	}
  
  	base64_encode(saltbytes, SALTLEN, &salt);
  	saltlen = strlen(salt);
  
  	PKCS5_PBKDF2_HMAC(password, strlen(password),
                  (unsigned char *)salt, saltlen,
  		iterations,
  		EVP_sha256(), KEY_LENGTH, key);
  
  	blen = base64_encode(key, KEY_LENGTH, &b64);
  	if (blen > 0) {
  		printf("PBKDF2$%s$%d$%s$%s\n",
  			"sha256",
  			iterations,
  			salt,
  			b64);
  		
  		free(b64);
  	}
  
  	free(password);
  	return 0;
  }
  