Explanation/Reference:
Explanation:
Public Key describes a system that uses certificates or the underlying public key cryptography on which the system is based.
In the traditional public key model, clients are issued credentials or "certificates" by a Certificate Authority (CA). The CA is a trusted third party. Public key certificates contain the user's name, the expiration date of the certificate etc. The most common certificate format is X.509. Public key credentials in the form of certificates and public-private key pairs can provide a strong distributed authentication system.
The Kerberos and public key trust models are very similar. A Kerberos ticket is analogous to a public key certificate (a Kerberos ticket is supplied to provide access to resources). However, Kerberos tickets usually have lifetimes measured in days or hours rather than months or years.
Incorrect Answers:
A: Kerberos tickets do not actually contain public keys. They use symmetric cryptography which uses one shared key instead of asymmetric cryptography which uses public-private key pairs.
B: Kerberos tickets do not contain private keys. They use symmetric cryptography which uses one shared key instead of asymmetric cryptography which uses public-private key pairs.
D: Private-key certificates are always kept by the authentication provider; they are never distributed to subjects that require access to resources. The public key is given to the subject to provide access to a resource in a similar way to a Kerberos ticket.
References:
Tipton, Harold F. and Micki Krause, Information Security Management Handbook, 5th Edition, Auerbach Publications, Boca Raton, 2006, p. 1438