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Posted by Kimmo Laine on 10/18/06 07:19
<weetat.yeo@gmail.com> wrote in message
news:1161153904.863203.327090@m73g2000cwd.googlegroups.com...
> Hi all ,
>
> I need to Security Matrix in my php project.
>
> The Security Matrix are Administrator , Engineer, Storeman and
> Customer.
> One of my peers said to make php project more robust, he asked me to
> use byte value as security matrix. For example as shown below:
>
> User id Name Security Matrix
> 1 A 15
> 2 B 1
> 3 C 2
>
> from table above user A is 1111
> (Administrator,Engineer,Storeman,Customer) , B is 0001 (Customer) and C
> is 0010 ( Storeman)
>
> My question is how i am going to check if the user is Administrator
> or Customer or etc ?
> Any php function to check it?
It's jsut plain and simple boolean math, althou I have no idea how this is
going to make it "more robust"...
When checking if a bitfield has a certain bit set, you use a bit mask and a
bitwise operation to compare them.
15 as binary is 1111, 1 is 0001 and 2 is 0010
Now, let's say user level of admin requires the fourth bit to be set, you
use a bit mask 8, 1000 as binary. Now to bitwise operation, we'll use AND
operation for comparison:
1000 & 1111 = 1000, now since 1000 is "not null", it's true, the guy really
is an admin. Now, what if he was storeman, say 0010. Again compare to 1000
using AND:
1000 & 0010 = 0000, it's null, the user isn't admin.
So basicly you just define the user right masks and use them to check the
user level.
$customer = bindec('0001');
$storeman = bindec('0010');
$engineer = bindec('0100');
$admin = bindec('1000');
if( $matrix & $admin )
echo("Hooray, you're an admin!");
if( $matrix & $engineer )
echo("You're an engineer, good for you!");
if( $matrix & $storeman )
echo("Just a storeman!");
if( $matrix & $custoimer )
echo("Boo-hoo, nothing but a lowly customer!");
Again, I see no connection between "robust" and this here, this is just a
way of storing multiple values to a single integer, but the reason this is
quite handy is that you can be an admin and an engineer at the same time as
"1100", but for example a normalized database would not allow multiple
values in one field, each field should be assigned one boolean field in a
database...
--
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