Which concept ensures that parties cannot deny sending messages in a communication?

The concept that ensures parties cannot deny sending messages in a communication is non-repudiation. Non-repudiation provides a guarantee that a sender cannot deny having sent a message, and a recipient cannot deny having received the message. This is typically achieved through methods such as digital signatures and secure logging mechanisms, which provide proof of the origin and integrity of the communication.

Non-repudiation is crucial in various fields, especially in legal and financial transactions, where it is essential to establish trust and accountability. By ensuring that both parties have verifiable evidence of their actions, non-repudiation helps prevent disputes and provides a layer of security in digital communications.

Authentication is about verifying the identity of the parties involved, while encryption focuses on securing the content of the message itself. Authorization deals with the permissions and access control over resources but does not pertain directly to the accountability of message-sending. Each of these concepts plays an important role in network security, but non-repudiation specifically addresses the issue of denying actions and provides a foundation for trust in communications.