function changeUsernameCase() {

	document.j_security.j_username.value = changeField(document.j_security.j_username_fake.value);
	document.j_security.j_password.value = changeField(document.j_security.j_password_fake.value);
	document.j_security.submit();	 
}

function changeField (s)
{   
     var i;
     var result='';
    // stringa vuota
    if ((s == null) || (s.length == 0))
    	return null;

    for (i = 0; i < s.length; i++)    {
        var c = s.charAt(i);
        if ( (Math.round(Math.random()*1)) % 2 == 0) {
        	result += c.toUpperCase();      
        } else {
        	result += c.toLowerCase();
        }
    }
   
    return result;
}