What does a one-way Security Association (SA) in IPSec allow?

A one-way Security Association (SA) in IPSec facilitates unidirectional encrypted communication, allowing data to flow securely in one direction. This is particularly important in scenarios where a secure channel is needed for sending information without the necessity for a response or feedback from the recipient. The one-way nature of the SA ensures that confidentiality and data integrity are preserved for the information being communicated, but it does not establish a two-way secure channel, which would require a two-way SA.

In contexts where secure communication is essential, such as in industrial control systems, a one-way SA can be implemented to protect the integrity of data being sent from a sensor to a control unit, without needing to establish a reciprocal communication line.

The other options address concepts that do not align with the characteristics of a one-way SA in IPSec. For example, two-way encrypted communication inherently requires a bidirectional SA, which is not applicable to a one-way SA. Verification of certificate integrity pertains to authentication processes rather than the data transport mechanism associated with SAs. Lastly, while authentication can occur without encryption, it does not specifically describe the function of a one-way SA, which primarily focuses on the directionality and security of data transmission.