CHAPTER 15: USER AUTHENTICATION PROTOCOLS
TRUE OR FALSE
T F 1. Kerberos provides a trusted third party authentication service that
enables clients and servers to establish authenticated
communication.
T F 2. Examples of dynamic biometrics include recognition by fingerprint,
retina, and face.
T F 3. User authentication is the means by which a user provides a
claimed identity to the system.
T F 4. Identity federation is in essence an extension of identity
management to multiple security domains.
T F 5. User authentication is the basis for most types of access control
and for user accountability.
T F 6. For network based user authentication the most important
methods involve cryptographic keys and something the individual
possesses, such as a smart card.
T F 7. There are a variety of problems including dealing with false
positives and false negatives, user acceptance, cost, and
convenience with respect to biometric authenticators.
T F 8. Any timestamp based procedure must allow for a window of time
sufficiently large enough to accommodate network delays yet
sufficiently small to minimize the opportunity for attack.
T F 9. An e–mail message should be encrypted such that the mail
handling system is not in possession of the decryption key.
T F 10. Because there are no potential delays in the e–mail process,
timestamps are extremely useful.
T F 11. The operating system cannot enforce access–control policies
based on user identity.
T F 12. The security of the Kerberos server should not automatically be
assumed, but must be guarded carefully by taking precautions
such as placing the server in a locked room.
T F 13. Once the server verifies that the user ID in the ticket is the same as
the unecrypted user ID in the message it considers the user
authenticated and grants the requested service.
T F 14. It is the ticket that proves the client’s identity.
T F 15. Identity providers may also assign attributes to users, such as
roles, access permissions, and employee information.
MULTIPLE CHOICE
1. __________ is an authentication service designed for use in a distributed
environment.
A. Kerberos B. PCBC
C. Toklas D. X.509
2. The __________ approach is unsuitable for a connectionless type of application
because it requires the overhead of a handshake before any connectionless
transmission, effectively negating the chief characteristic of a connectionless
transaction.
A. timestamp B. backward reply
C. challenge-response D. replay
3. A common item of authentication information associated with a user is a
___________ .
A. nonce B. timestamp
C. ticket D. password
4. The overall scheme of Kerberos is that of a trusted third party authentication
service that uses a protocol based on a proposal by __________ .
A. Needham and Schroeder B. Kehn
C. Denning D. Gong
5. ________ is a procedure that allows communicating parties to verify that the
contents of a received message have not been altered and that the source is
authentic.
A. Identification B. Message authentication
C. Verification D. User authentication
6. Presenting an identifier to the security system is the __________ step.
A. authentication B. verification
C. identification D. clarification
7. Presenting or generating authentication information that corroborates the
binding between the entity and the identifier is the ___________ step.
A. identification B. verification
C. clarification D. authentication
8. The __________ is unsuitable for a connectionless type of application because it
requires the overhead of a handshake before any connectionless
transmission, effectively negating the chief characteristic of a connectionless
transaction.
A. timestamp approach B. challenge-response approach
C. simple replay approach D. one-way authentication approach
9. Kerberos relies exclusively on __________ .
A. symmetric encryption B. asymmetric encryption
C. private key encryption D. public key encryption
10. A Kerberos __________ is a set of managed nodes that share the same Kerberos
database.
A. realm B. TGS
C. network D. principal
11. In an unprotected network environment any client can apply to any server
for service. The obvious security risk of this is __________ .
A. certification B. authentication
C. impersonation D. authorization
12. A service to solve the problem of minimizing the number of times that a user
has to enter a password and the risk of an eavesdropper capturing the
password and using it is known as the __________ .
A. authentication server B. ticket granting server
C. Kerberos mutual authentication D. PCBC mode
13. A centralized, automated approach to provide enterprise-wide access to
resources by employees and other authorized individuals with a focus of
defining an identity for each user, associating attributes with the identity,
and enforcing a means by which a user can verify identity is __________ .
A. enterprise management B. identity management
C. federated identity management D. realm management
14. __________ is an extension of identity management to multiple security
domains such as autonomous internal business units, external business
partners and other third party applications and services with the goal of
sharing digital identities so that a user can be authenticated a single time and
then access applications and resources across multiple domains.
A. Identity federation B. Kerberos
C. Attribute service D. Data security management
15. The principal underlying standard for federated identity is the __________
which defines the exchange of security information between online business
partners.
A. OSAIS B. SAML
C. RBAC D. SFIL
SHORT ANSWER
1. _________ protocols enable communicating parties to satisfy themselves
mutually about each other’s identity and to exchange session keys.
2. __________ in Greek mythology is a three headed dog with a serpent’s tail that
guards the entrance of Hades.
3. There are four general means of authenticating a user’s identity. They are:
something the individual knows, something the individual possesses,
something the individual is, and something the individual __________ .
4. To convince the server that a user is authentic, the authentication server
creates a _________ that contains the user’s ID and network address and the
server’s ID and sends it back to the client so they can continue the request for
service.
5. An authentication process consists of two steps: identification step and
__________ step.
6. ____________ is a centralized, automated approach to provide enterprise wide
access to resources by employees and other authorized individuals.
7. The first published report on Kerberos listed the following requirements:
secure, reliable, scalable and __________ .
8. Examples of something the individual possesses would include cryptographic
keys, electronic keycards, smart cards, and physical keys. This type of
authenticator is referred to as a __________ .
9. The _________ is responsible for generating keys to be used for a short time
over a connection between two parties and for distributing those keys using
the master keys to protect the distribution.
10. A __________ attack is where an opponent intercepts a message from the
sender and replays it later when the timestamp in the message becomes
current at the recipient’s site.
11. __________ is an authentication service developed as part of Project Athena at
MIT.
12. A solution, which eliminates the burden of each server having to confirm the
identities of clients who request service, is to use an __________ that knows the
passwords of all users and stores these in a centralized database and shares a
unique secret key with each server.
13. The ticket granting ticket is encrypted with a secret key known only to the
AS and the __________ .
14. Intended to provide an integrity check as part of the encryption operation,
encryption in Kerberos Version 4 makes use of a nonstandard mode of DES
known as ____________. It has been demonstrated that this mode is vulnerable
to an attack involving the interchange of ciphertext blocks.
15. A concept dealing with the use of a common identity management scheme
across multiple enterprises and numerous applications and refers to the
agreements, standards, and technologies that enable the portability of
identities, identity attributes, and entitlements across multiple enterprises
and numerous applications and supporting many thousands, even millions,
of users is _________ .
TRUE OR FALSE
MULTIPLE CHOICE
SHORT ANSWER
