Explanation/Reference:
Explanation:
With Link Encryption each entity has keys in common with its two neighboring nodes in the transmission chain. Thus, a node receives the encrypted message from its predecessor (the neighboring node), decrypts it, and then re-encrypts it with another key that is common to the successor node. Then, the encrypted message is sent on to the successor node where the process is repeated until the final destination is reached. Obviously, this mode does not provide protection if the nodes along the transmission path can be compromised.
Incorrect Answers:
A: It is not true that each entity has a common key with the destination node. Each entity has keys in common with only its two neighboring nodes.
B: It is not true that encrypted messages are only decrypted by the final node. Every node in the chain (except the original sending node) decrypts the message.
D: It is not true that only secure nodes are used in this type of transmission. The data is encrypted for security; the nodes themselves can be insecure.
References:
Krutz, Ronald L. and Russel Dean Vines, The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, New York, 2001, p. 126