Kerberos
Kerberos is a computer network authentication protocol and is ticket-based allowing nodes to communicate over a non-secure. Massachusetts institute of technology (mit) developed the kerberos to protect network services provided by the project athena. This protocol is based on the earlier needham–schroeder symmetric key protocol. Kerberos protocol messages are protected against snooping and replay attacks.
Kernel
The kernel is an essential center of a computer operating system, the core that provides basic services for all other parts of the operating system. A synonym is nucleus. A kernel can be contrasted with a shell, the outermost part of an operating system that interacts with user commands. Kernel and shell are terms used more frequently in unix operating systems than in ibm mainframe or microsoft windows systems.