Remove IDs in thread URL?

[Onur]

decode the ID in roman numbers ?

1 = I
2 = II
..
5 = V

like this Topis was
[forum_path]/ix-vii-ii-viii/[thread_title].html

just an idea or use another decryption from numbers to chars

but this was real a unperformed funtion

or use somthing like this

function encrypt($input)
{
	$output = '';
	$code = array(
	1 => 'a',
	2 => 'b',
	3 => 'c',
	4 => 'd',
	5 => 'e',
	6 => 'f',
	7 => 'g',
	8 => 'h',
	9 => 'i',
	0 => 'o',
	'.' => 'z',
	',' => 'y');

	$chars = strlen($input);
	
	for($i = 0; $i < $chars; $i++)
	{	
		$output .= $code[substr($input, $i, 1)];
	}
	
	
	return $output;

}
function decrypt($input)
{
	$output = '';
	$code = array(
	'a' => 1,
	'b' => 2,
	'c' => 3,
	'd' => 4,
	'e' => 5,
	'f' => 6,
	'g' => 7,
	'h' => 8,
	'i' => 9,
	'o' => 0,
	'z' => '.',
	'y' => ',');

	$chars = strlen(strtolower($input));
	
	for($i = 0; $i < $chars; $i++)
	{	
		$count = substr($input, $i, 1);
		$output .= $code[$count];
	}
	
	
	return $output;

}