CCSP Self-Study: Securing Cisco IOS Networks (SECUR)

Certificate Authorities

The use of pre-shared keys is a straightforward process for device or user authentication. An administrator assigns a key to each host or user and then configures the server to respond only to those pre-shared keys. It is a simple process, but it does not scale well to large organizations where there may be hundreds or thousands of keys to keep track of.

Digital certificates were developed as a method of automating the assignment and maintenance of security keys and form the basis of the Public Key Infrastructure (PKI). Ronald Rivest, Adi Shamir, and Leonard Adleman developed the RSA public-key cryptosystem in 1977. In this system, a CA provides RSA digital certificates upon registration with that CA. These digital certificates ...