Ace, Acl, Sid

[benchin]

Well, I keep seeing this word "ACE", "ACL", "SID" in the Windows API, GetFileSecurity and SetFileSecurity. Can anyone tell me what do they mean? I think it is some sort of constant but what is the exact words and what do they represent? Please help...

[Vlatko]

ACL = access-control list
SID = security identifier

Remarks
A security descriptor includes information that specifies the following components of an object's security: 

An owner (SID) 
A primary group (SID) 
A discretionary ACL 
A system ACL 
Qualifiers for the preceding items 
Security descriptors use access-control lists (ACLs) and security identifiers (SIDs) to specify the information in this list. 

A security descriptor can be in absolute or self-relative form. In self-relative form, all members of the structure are located contiguously in memory. In absolute form, the structure only contains pointers to the members.

[jim mcnamara]

An acl is has a header and ace (access control entry) members -
there may be zero aces.

Each ace enables, limits or fully disables access for a particular identifier - user name, user group, class, node, etc.