What is a storage channel in information security?

A storage channel refers to a covert channel that utilizes shared storage mechanisms to transmit information in a way that is not intended by the system's design. This involves using a common storage area where two processes can manipulate data without explicit authorization to communicate, typically in systems where access controls are enforced. Since traditional security measures focus on controlling direct communication paths, a storage channel can allow unauthorized data transfer between processes that have different security classifications.

In this context, the other options do not accurately define a storage channel. For instance, a network protocol for secure communication refers to rules and conventions for data transfer over networks but does not pertain to covert information transfer through storage. A method of data encryption typically involves algorithms designed to protect data confidentiality, which is quite different from the idea of covert channels. Lastly, user authentication processes focus on verifying the identity of users accessing a system and are unrelated to covertly transferring unauthorized information. Hence, the definition of a storage channel as a covert channel using shared storage encapsulates the concept effectively.