Security permissions

<?php

// Security permissions:
$writePost = 1;
$readPost = 2;
$deletePost = 4;
$addUser = 8;
$deleteUser = 16;

// User groups:
$administrator = $writePost | $readPost | $deletePost | $addUser | $deleteUser;
$moderator = $readPost | $deletePost | $deleteUser;
$writer = $writePost | $readPost;
$guest = $readPost;

function checkPermission($user, $permission) {
    if($user & $permission) {
        return true;
    } else {
        return false;
    }
}

function hasPermission($user, $permission) {
    return (($user & $permission) == $permission);
}

if(checkPermission($administrator, $deleteUser)) {
    var_dump('administrator can delete user');
} else {
    var_dump('administrator cannot delete user');
}

if(checkPermission($guest, $deleteUser)) {
    var_dump('guest can delete user');
} else {
    var_dump('guest cannot delete user');
}

if(checkPermission($writer, $guest)) {
    var_dump('writer has similarity with guest');
}

if(checkPermission($guest, $writer)) {
    var_dump('guest has similarity with writer');
}

if(hasPermission($writer, $guest)) {
    var_dump('writer is guest');
}

if(hasPermission($guest, $writer)) {
    var_dump('guest is writer');
}

if(checkPermission($administrator, $moderator)) {
    var_dump('administrator has similarity with moderator');
}

if(checkPermission($moderator, $administrator)) {
    var_dump('moderator has similarity with administrator');
}

if(hasPermission($administrator, $moderator)) {
    var_dump('administrator is moderator');
}

if(hasPermission($moderator, $administrator)) {
    var_dump('moderator is administrator');
}

// display : 
// string 'administrator can delete user' (length=29)
// string 'guest cannot delete user' (length=24)
// string 'writer has similarity with guest' (length=32)
// string 'guest has similarity with writer' (length=32)
// string 'writer is guest' (length=15)
// string 'administrator has similarity with moderator' (length=43)
// string 'moderator has similarity with administrator' (length=43)
// string 'administrator is moderator' (length=26)
?>