Which proprietary protocol is designed to function exclusively on Cisco devices?

Lightweight EAP (LEAP) is a proprietary authentication protocol developed by Cisco specifically for use with Cisco wireless devices. It provides a method for secure network access by allowing users to authenticate with username and password credentials, using a shared secret for encryption. LEAP is designed to address some of the limitations of earlier protocols, such as static WEP, by utilizing mutual authentication between the client and the access point.

This protocol operates exclusively on Cisco devices, meaning that it relies on Cisco's specific implementations and may not be compatible with other vendor equipment. LEAP was widely used in earlier wireless networks but has been largely replaced by more secure and standardized protocols, such as WPA2.

In contrast, the other options do not fit the criteria of a proprietary protocol designed for exclusive use on Cisco devices. Protected EAP (PEAP) and OpenID are open frameworks that may be implemented across various devices and networking equipment. JSON Web Token (JWT) is a compact and self-contained way for securely transmitting information between parties as a JSON object, but it is not an authentication protocol in the same context as LEAP.