<?php

	$cadena = "abcdefghijklmnopqrstuvwxyz";
	$cadena2 = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
	$cadena3 = "0123456789";
	$cadena4 = "qwertyuiopasdfghjklzxcvbnm";
	$cadena5 = "QWERTYUIOPASDFGHJKLZXCVBNM";


	$sub = substr($cadena,rand(0,36),4);
	$sub2 = substr($cadena2,rand(0,36),4);
	$sub3 = substr($cadena3,rand(0,10),4);
	$sub4 = substr($cadena4,rand(0,32),4);
	$sub5 = substr($cadena5,rand(0,32),4);

	$stringfinal = $sub . $sub2 . $sub3 . $sub4 . $sub5;


		for($i = 0; $i < strlen($stringfinal) ; $i++)
		{
			$rand = rand(0,strlen($stringfinal)-1);
			$stringfinal[$i] = $stringfinal[$rand];

			if(strlen($stringfinal) < 10)
			{
				$i = $i -1;
				$rand2 = rand(0,strlen($stringfinal)-1);
				$stringfinal[$rand] = $stringfinal[$rand2];

			}


		}

	var_dump($stringfinal);
?>