I learned that in authorization there are somethings to keep in mind, there are:

-Authorization Creep this happens when an employee switch roles and the previous authorization isnt removed.
-Default to Zero
-Need to know Principle to limit information to someone that not need to know of the information
-Access Control List is a list of permissions attached to an object. An ACL specifies which users or system processes are granted access to objects, as well as what operations are allowed on given objects.

I have tried to search what is Default to Zero means on this, but I cant find it.
What does default to zero in this context means?


1 Answer 1


It appears to be "default to zero privileges, unless proven otherwise".

E.g. writing code like:

access_flags = NONE
if password_match:

Instead of:

if not password_match:

Reason being that it's easier to make (and exploit) mistakes in latter code. In the above example, latter code would still leave ADMIN privileges if passwords don't match.

  • could you please explain to me the differences of !password_match() and password_match, access_flags |= ACCESS_USER and &= !ACCESS_USER?
    – Vlanzyvinz
    Nov 9, 2016 at 17:05
  • rewritten pseudo code to be more english-like. clearer?
    – domen
    Nov 9, 2016 at 17:18
  • oh, then that means before adding new access, we set the flags to zero first like on the first pseudo code?
    – Vlanzyvinz
    Nov 9, 2016 at 17:25
  • I interpret it to start with zero access/privileges/permissions, and then add the appropriate on authentication.
    – domen
    Nov 9, 2016 at 17:28
  • 1
    Don't accept answer so quickly. Normally you should give it a day or two, otherwise you'll discourage other people from answering.
    – domen
    Nov 9, 2016 at 17:29

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