Which security principle ensures users have no more access than necessary?

The least privilege principle is a fundamental security concept that mandates that users should only have the minimum level of access necessary to perform their job functions. This principle is crucial for minimizing potential security risks, as it limits the opportunities for unauthorized access or misuse of sensitive information and resources.

By adhering to the least privilege principle, organizations can significantly reduce their exposure to threats, as it restricts users from gaining access to information or systems that are unrelated to their responsibilities. Implementing this principle effectively involves assigning permissions based on the specific needs of users, regularly reviewing access rights, and promptly revoking access when it is no longer required.

In contrast, the other options, while relevant to security, do not specifically embody the concept of limiting access for users to the least necessary levels. Role-based access control focuses on grouping users based on their roles and assigning permissions accordingly but does not inherently enforce the least privilege concept. Data encryption policies deal with securing data in transit or at rest, and network segmentation protocols are about dividing a network into segments to improve security but do not directly relate to user access levels. Hence, the least privilege principle is the most accurate choice in this context.