An Access Control Entry (ACE) is the fundamental unit within an Access Control List (ACL). In the context of a Discretionary Access Control List (DACL), each ACE explicitly defines the access permissions for a specific security principal (a user, group, or computer, identified by a Security Identifier or SID). The ACE specifies what actions (e.g., read, write, execute) are allowed or denied for that principal on the associated object. The DACL itself is the container that holds a collection of these individual ACEs.

B. Discretionary access control entry (DACE): This is not a standard, recognized term in security architecture or official documentation. The correct term is Access Control Entry (ACE).
C. Access control list (ACL): An ACL is the entire list or collection of ACEs. The question asks for the individual entry within the list, not the list itself.
D. Security Identifier (SID): A SID is a unique value that identifies a security principal. While an ACE contains a SID to specify who the rule applies to, the SID is only one component of the ACE, not the entire entry.

1. Microsoft Corporation. (2021). Access Control Entries (ACEs). Microsoft Learn. Retrieved from https://learn.microsoft.com/en-us/windows/win32/secauthz/access-control-entries.

Reference Detail: The document states

"An access control entry (ACE) is an entry in an access control list (ACL). An ACL can have zero or more ACEs... Each ACE contains a set of access rights and a security identifier (SID) that identifies a trustee for whom the rights are allowed

denied

or audited."

2. Microsoft Corporation. (2021). Discretionary Access Control Lists (DACLs). Microsoft Learn. Retrieved from https://learn.microsoft.com/en-us/windows/win32/secauthz/discretionary-access-control-lists--dacls--and-aces.

Reference Detail: This document explicitly states

"A discretionary access control list (DACL) is a list of access-control entries (ACEs)." This clarifies the hierarchical relationship where the DACL contains ACEs.

3. Jaeger

T. (2008). Operating System Security. Morgan & Claypool Publishers.

Reference Detail: Chapter 4

"Authorization

" Section 4.2.1

"Access Control Lists

" describes that an ACL is a list of entries

where each entry (an ACE) is a pair of a subject (e.g.

user or group) and their authorized operations (permissions) for the object.

4. Perrig

A.

& Song

D. (2014). CS 15-410 Operating System Design and Implementation

Lecture 21: Protection & Security. Carnegie Mellon University

School of Computer Science.

Reference Detail: Slide 21

"Access Control Lists (ACLs)

" defines an ACL as a list of pairs: < principal

rights-set >. This pair is functionally an Access Control Entry (ACE)

demonstrating the academic definition aligns with the technical one.