Confidentiality is the security concept that ensures that sensitive information is accessed only by an authorized person and kept away from those not authorized to possess it. It restricts access to data to protect it from unauthorized users. While Integrity ensures that the data is reliable and accurate, Authenticity verifies the identities of entities involved in a communication, and Non-Repudiation prevents entities from denying their actions; none of these concepts primarily focuses on restricting access to protect data.