How-to create a Password Generator using PHP

Olaf — Sun, 22 Nov 2009 15:54:50 +0000

Do you need a password generator function for your user registration application or do you have to write a script in PHP? Than is this PHP tutorial for you. The function in this guide is flexible enough to use it during the user registration process or for a password recovery function. The generated password from this function is so safe as you which: Generate alpha-numerical password combined with capital character or with special signs or characters. All used character are based on the number from the ASCII table.

In this tutorial we will explain all the important code, find the complete function at the begin of this tutorial. We used the tutorial code also for our Google Gadget, you can try it just by adding the gadget to your iGoogle start page.

The PHP code for the function

function create_password($pw_length = 8, $use_caps = true, $use_numeric = true, $use_specials = true) {
	$caps = array();
	$numbers = array();
	$num_specials = 0;
	$reg_length = $pw_length;
	$pws = array();
	for ($ch = 97; $ch <= 122; $ch++) $chars[] = $ch; // create a-z
	if ($use_caps) for ($ca = 65; $ca <= 90; $ca++) $caps[] = $ca; // create A-Z
	if ($use_numeric) for ($nu = 48; $nu <= 57; $nu++) $numbers[] = $nu; // create 0-9
	$all = array_merge($chars, $caps, $numbers);
	if ($use_specials) {
		$reg_length =  ceil($pw_length*0.75);
		$num_specials = $pw_length - $reg_length;
		if ($num_specials > 5) $num_specials = 5;
		for ($si = 33; $si <= 47; $si++) $signs[] = $si;
		$rs_keys = array_rand($signs, $num_specials);	
		foreach ($rs_keys as $rs) {
			$pws[] = chr($signs[$rs]);
		}
	} 
	$rand_keys = array_rand($all, $reg_length);
	foreach ($rand_keys as $rand) {
		$pw[] = chr($all[$rand]);
	}	
	$compl = array_merge($pw, $pws);	
	shuffle($compl);
	return implode('', $compl);
}

We create a for loop to build our arrays with characters, while the default characters are always included, we use if statements to include the capital or numeric characters.

	for ($ch = 97; $ch <= 122; $ch++) $chars[] = $ch; // create a-z
	if ($use_caps) for ($ca = 65; $ca <= 90; $ca++) $caps[] = $ca; // create A-Z
	if ($use_numeric) for ($nu = 48; $nu <= 57; $nu++) $numbers[] = $nu; // create 0-9

After this, we merge the three arrays together into one array called $all:

	$all = array_merge($chars, $caps, $numbers);

If the function is configured to use special characters, we use 25% from the password length for these characters. Next we check the number of used special character, if we reach 5 of them (based on the 25% from the password length) we replace the value with 5.

		$reg_length =  ceil($pw_length*0.75);
		$num_specials = $pw_length - $reg_length;
		if ($num_specials > 5) $num_specials = 5;

As before we use a for loop to create the array with special characters. We use the array_rand function to create another array with random keys and the foreach loop will add the values to the array $pws.

		for ($si = 33; $si <= 47; $si++) $signs[] = $si;
		$rs_keys = array_rand($signs, $num_specials);
		foreach ($rs_keys as $rs) {
			$pws[] = chr($signs[$rs]);
		}

With the same method as for the special characters we will build the array $pw using the alpha-numerical array.

	$rand_keys = array_rand($all, $reg_length);
	foreach ($rand_keys as $rand) {
		$pw[] = chr($all[$rand]);
	}

The next code will merge the two password arrays and after we used the function shuffle before the password is returned as a string (using the implode function).

	$compl = array_merge($pw, $pws);	
	shuffle($compl);
	return implode('', $compl);

With function it’s very easy to create a random password in your application, just use it this way:

$password = create_password(12, false, true, false); // creates 12 character alpha-numeric password

What do you think what could be better? Maybe we can segment the amount of numbers or capitals? If you like to use less different characters, just decrease the numbers inside the for loops. Use this ASCII table as your reference. Please post your comments below or open a thread on our PHP forum at finalwebsites.com.

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How-to create a Password Generator using PHP

The PHP code for the function