What does confidentiality in information security primarily ensure?

Confidentiality in information security primarily ensures that access to data is denied to unauthorized users. This principle is fundamental as it focuses on protecting sensitive information from being accessed or viewed by individuals who do not have the proper permissions. Implementing confidentiality measures such as encryption, access controls, and authentication protocols helps safeguard data from unauthorized disclosure, thereby maintaining its privacy and integrity.

The other options, while related to overall information security, focus on different aspects. Availability concerns ensuring that authorized users can access data when needed, integrity focuses on preventing unauthorized changes to data, and the ease of data transfer does not directly relate to the concept of confidentiality. These different facets collectively contribute to the security of information systems, but confidentiality specifically addresses the protection of data from unauthorized access.