PHP Random password generator

function GeneratePassword($length=8, $strength=0){
    $vowels = 'aeuy';
    $consonants = 'bcdghjmnpqrstvw';
    if($strength >= 1) $consonants .= 'BCDGHJLMNPQRSTVW';
    if($strength >= 2) $vowels .= 'AEUY';
    if($strength >= 3) $consonants .= '12345';
    if($strength >= 4) $consonants .= '67890';
    if($strength >= 5) $vowels .= '@#$%';

    $password = '';
    $alt = time() % 2;
    for($i = 0; $i < $length; $i++){
        if($alt == 1){
            $password .= $consonants[(rand() % strlen($consonants))];
            $alt = 0;
        }else{
            $password .= $vowels[(rand() % strlen($vowels))];
            $alt = 1;
        }
    }
    return $password;
}