Generating Random Passwords

Random (but difficult-to-guess) strings are important in user security. For example, if someone loses a password and you're using MD5 hashes, you won't be able to, nor should you want to, look it up. Instead, you should generate a secure random password and send that to the user. Another application for random number generation is creating activation links in order to access your site's services. Here is a function that creates a password:

<?php
function make_password($num_chars) {
 if ((is_numeric($num_chars)) && ($num_chars > 0) && (! is_null($num_chars))) {
  $password = '';
  $accepted_chars = 'abcdefghijklmnopqrstuvwxyz1234567890';
  // Seed the generator if necessary.
  srand(((int)((double)microtime()*1000003)) );
  for ($i=0; $i<=$num_chars; $i++) {
   $random_number = rand(0, (strlen($accepted_chars) -1));
   $password .= $accepted_chars[$random_number] ;
  }
 return $password;
 }
}
?>

Using above function The make_password() function returns a string, so all you need to do is supply the length of the string as an argument:

<?php
$fifteen_character_password = make_password(15);
?>