Network Security Essentials Applications and Standards 5th Edition By Willaim Stallings – Test Bank
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Sample
Test
Chapter 3: Public-Key Cryptography and Message
Authentication
TRUE OR FALSE
T
F 1. Public key
algorithms are useful in the exchange of conventional
encryption keys.
T
F 2. Private key encryption
is used to produce digital signatures which
provide an enhanced form of message authentication.
T
F 3.
The
strength of a hash function against brute-force attacks
depends solely on the length of the hash code produced by the
algorithm.
T
F 4. The two
important aspects of encryption are to verify that the
contents of the message have not been altered and that the
source
is authentic.
T
F 5. In the ECB
mode of encryption if an attacker reorders the blocks of
ciphertext then each block will still decrypt successfully,
however,
the reordering may alter the meaning of the overall data
sequence.
T
F 6. Message
encryption alone provides a secure form of authentication.
T
F 7. Because of the
mathematical properties of the message
authentication code function it is less vulnerable to being
broken
than encryption.
T
F 8. In addition to
providing authentication, a message digest also
provides data integrity and performs the same function as a
frame
check sequence.
T
F 9. Cryptographic
hash functions generally execute slower in software
than conventional encryption algorithms such as DES.
T F
10. The main advantage of HMAC over other proposed hash based
schemes is that HMAC can be proven secure, provided that the
embedded hash function has some reasonable cryptographic
strengths.
T
F 11. Public key
algorithms are based on mathematical functions rather
than on simple operations on bit patterns.
T
F 12. The private
key is known only to its owner.
T
F 13.
The
security of the Diffie-Hellman key exchange lies in the fact
that, while it is relatively easy to calculate exponentials
modulo a
prime, it is very easy to calculate discrete logarithms.
T
F 14. The key
exchange protocol is vulnerable to a man-in-the-middle
attack because it does not authenticate the participants.
T
F 15. Even in the
case of complete encryption there is no protection of
confidentiality because any observer can decrypt the message by
using the sender’s public key.
MULTIPLE CHOICE
1. ________
protects against passive attacks (eavesdropping).
1. Obfuscation
B. Encryption
1. SCR
D. Message authentication
2. The
most important hash function is ________ .
1. MAC
B. SHA
1. OWH
D. ECB
3. __________
is a procedure that allows communicating parties to verify that received
messages are authentic.
1. ECB
B.
Message authentication
1. Passive
attack
D.
Encryption
4. If
the message includes a _________ the receiver is assured that the message has not
been delayed beyond that normally expected for network transit.
1. sequence
number
B. shared key
1. error
detection code
D. timestamp
5. The
purpose of a ___________ is to produce a “fingerprint” of a file, message, or
other block of data.
1. hash function
B.
public key
1. message
authentication
D.
cipher encryption
6. It is
computationally infeasible to find any pair (x, y) such that H(x) = H(y). A
hash function with this property is referred to as __________ .
1. collision
resistant
B. preimage resistant
1. one-way
D.
weak collision resistant
7. “It
is easy to generate a code given a message, but virtually impossible to
generate a message given a code” describes the __________ hash function property.
1. second
preimage resistant
B. preimage resistant
1. strong
collision resistant
D. collision resistant
8. The
__________ property protects against a sophisticated class of attack known as
the birthday attack.
1. preimage
resistant
B. one-way
1. collision
resistant
D. second preimage resistant
9. Secure
Hash Algorithms with hash value lengths of 256, 384, and 512 bits are
collectively known as _________ .
1. SHA-0
B. SHA-3
1. SHA-2
D. SHA-1
10. Public
key cryptography is __________ .
1. bit
patterned
B. one key
1. symmetric
D. asymmetric
11. The
readable message or data that is fed into the algorithm as input is the
__________ .
1. ciphertext
B. plaintext
1. encryption
algorithm
D.
private key
12. The
key used in conventional encryption is typically referred to as a _________
key.
1. secondary
B. primary
1. cipher
D. secret
13. The
most widely accepted and implemented approach to public-key encryption,
_________ is a block cipher in which the plaintext and ciphertext are integers
between 0 and n – 1 for some n.
1. MD5
B. RSA
1. SHA
D. CTR
14. The
purpose of the _________ algorithm is to enable two users to exchange a secret
key securely that then can be used for subsequent encryption of messages and
depends on the difficulty of computing discrete logarithms for its
effectiveness.
1. Diffie-Hellman
B. RSA
1. DSS
D. Rivest-Adleman
15. Based
on the use of a mathematical construct known as the elliptic curve and offering
equal security for a far smaller bit size, __________ has begun to challenge
RSA.
1. DSS
B. TCB
1. RIPE-160
D. ECC
SHORT ANSWER
1. Protection
against active attacks (falsification of data and transactions) is known
as ___________ .
2. The
__________ property is the “one-way” property and is important if the
authentication technique involves the use of a secret value.
3. The
__________ approach has two advantages: it provides a digital signature as well
as message authentication and it does not require the
distribution of keys to
communicating parties.
4. Like
the MAC, a __________ accepts a variable size message M as input and produces
a fixed size message digest H(M) as output. Unlike the
MAC, it does not take a
secret key as input.
5. The
__________ property guarantees that it is impossible to find an alternative
message with the same hash value as a given message, thus
preventing forgery
when an encrypted hash code is used.
6. As
with symmetric encryption, there are two approaches to attacking a secure
hash function: brute-force attack and ___________ .
7. The
two most widely used public key algorithms are RSA and _________ .
8. The
_________ was developed by NIST and published as a federal information
processing standard in 1993.
9. __________
is a term used to describe encryption systems that simultaneously
protect confidentiality and authenticity (integrity) of
communications.
10. The
key algorithmic ingredients of __________ are the AES encryption algorithm,
the CTR mode of operation, and the CMAC authentication
algorithm.
11. The
__________ algorithm accepts the ciphertext and the matching key and
produces the original plaintext.
12. A
__________ is when the sender “signs” a message with its private key, which is
achieved by a cryptographic algorithm applied to the message or
to a small
block of data that is a function of the message.
13. A
_________ is when two sides cooperate to exchange a session key.
14. Using
an algorithm that is designed to provide only the digital signature
function, the _________ makes use of the SHA-1 and cannot be
used for encryption
or key exchange.
15. Bob
uses his own private key to encrypt the message. When Alice receives the
ciphertext she finds that she can decrypt it with Bob’s public
key, thus proving
that the message must have been encrypted by Bob. No one
else has Bob’s
private key and therefore no one else could have created a
ciphertext that could
be decrypted with Bob’s public key. Therefore the entire
encrypted message
serves as a _________ .
Chapter 3: Public-Key Cryptography and Message
Authentication
TRUE OR FALSE
1. T
2. F
3. T
4. F
5. T
6. F
7. T
8. T
9. F
10. T
11. T
12. T
13. F
14. T
15. T
MULTIPLE CHOICE
1. B
2. B
3. B
4. D
5. A
6. A
7. B
8. C
9. C
10. D
11. B
12. D
13. B
14. A
15. D
SHORT ANSWER
1. message
authentication
2. preimage
resistant
3. public-key
4. hash
function
5. second
preimage resistant
6. cryptanalysis
7. Diffie-Hellman
8. Secure
Hash Algorithm (SHA)
9. Authenticated
encryption
10. CCM
11. decryption
12. digital
signature
13. key
exchange
14. Digital
Signature Standard (DSS)
15. digital
signature
Chapter 4: Key Distribution and User Authentication
TRUE OR FALSE
T
F 1. For symmetric
encryption to work the two parties to an exchange
must share the same key, and that key must be protected from
access by others.
T
F 2. It is not
necessary for a certification authority to maintain a list of
certificates issued by that CA that were not expired but were
revoked.
T
F 3.
A
session key is destroyed at the end of a session.
T
F 4. Kerberos
relies exclusively on asymmetric encryption and makes
use of public key encryption.
T
F 5.
The
automated key distribution approach provides the flexibility
and dynamic characteristics needed to allow a number of users to
access a number of servers and for the servers to exchange data
with each other.
T
F 6.
If an
opponent captures an unexpired service granting ticket and
tries to use it they will be denied access to the corresponding
service.
T
F 7.
The
ticket-granting ticket is encrypted with a secret key known
only to the authentication server and the ticket granting
server.
T
F 8.
If
the lifetime stamped on a ticket is very short (e.g., minutes) an
opponent has a greater opportunity for replay.
T
F 9. Kerberos
version 4 did not fully address the need to be of general
purpose.
T
F 10.
One
of the major roles of public-key encryption is to address the
problem of key distribution.
T
F 11. It is not
required for two parties to share a secret key in order to
communicate securely with conventional encryption.
T
F 12. X.509 is based
on the use of public-key cryptography and digital
signatures.
T
F 13.
User
certificates generated by a CA need special efforts made by
the directory to protect them from being forged.
T
F 14. The principal
underlying standard for federated identity is the
Security Assertion Markup Language (SAML) which defines the
exchange of security information between online business
partners.
T
F 15.
Federated
identity management is a concept dealing with the use
of a common identity management scheme across multiple
enterprises and numerous applications and supporting many
thousands, even millions, of users.
MULTIPLE CHOICE
16. A
_________ is a key used between entities for the purpose of distributing
session keys.
1. A)
permanent
key
B)
key distribution center
1. C)
symmetric
key
D)
session relay key
2. The
__________ knows the passwords of all users and stores these in a centralized
database and also shares a unique secret key with each server.
1. A)
authentication
server
B)
key distribution server
1. C)
management
server
D)
ticket server
3. Once
the authentication server accepts the user as authentic it creates an
encrypted _________ which is sent back to the client.
1. A)
password
B)
key
1. C)
access
code
D)
ticket
4. In
order to solve the problem of minimizing the number of times that a user
has to enter a password and the problem of a plaintext
transmission of the
password a __________ server is used.
1. A)
ticket
granting
B)
password ciphering
1. C)
access
code
D)
authentication
5. In
order to prevent an opponent from capturing the login ticket and reusing it to
spoof the TGS, the ticket includes a __________ indicating the date and time at
which the ticket was issued.
1. validation
B.
certificate
1. timestamp
D. realm
6. A
___________ is a service or user that is known to the Kerberos system and is
identified by its principal name.
1. Kerberos
key
B.
Kerberos ticket
1. Kerberos
principal
D. Kerberos realm
7. Kerberos
version 4 requires the use of a(n) ____________ .
1. IP
address
B. Ethernet link address
1. ISO
network address
D. MAC
address
8. Encryption
in version 4 makes use of a nonstandard mode of DES known as ___________ .
1. KDC
B. CBC
1. PCBC
D. PKI
9. A
random value to be repeated to assure that the response is fresh and has not
been replayed by an opponent is the __________ .
1. nonce
B. option
1. rtime
D. realm
10. Used
in most network security applications, the __________ standard has become
universally accepted for formatting public-key certificates.
1. IETF
B. X.905
1. PKIX
D. X.509
11. Containing
the hash code of the other fields encrypted with the CA’s private key, the
__________ covers all of the other fields of the certificate and includes the
signature algorithm identifier.
1. extension
B.
signature
1. issuer
unique identifier
D.
subject unique identifier
12. The
_________ extension lists policies that the certificate is recognized as
supporting, together with optional qualifier information.
1. policy
mappings
B.
directory attribute
1. certificate
policies
D. authority key identifier
13. _________
are entities that obtain and employ data maintained and provided by identity
and attribute providers, which are often used to support authorization
decisions and to collect audit information.
1. Federations
B. Principals
1. CAs
D.
Data Consumers
14. An
__________ manages the creation and maintenance of attributes such as passwords
and biometric information.
1. attribute
service
B. authenticator
1. identity
provider
D. authorizing agent
15. __________
is 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.
1. Registration
authority
B. Federated managing authority
1.
Identity management
D.
PKIX management
SHORT ANSWER
1. The
strength of any cryptographic system rests with the _________ technique, a
term that refers to the means of delivering a key to two parties
that wish to exchange data without allowing others to see the key.
2. A __________
indicates the length of time for which a ticket is valid (e.g., eight hours).
3. When
two end systems wish to communicate they establish a logical connection and,
for the duration of that logical connection, all user data are encrypted with a
one-time __________ which is destroyed at the end of the session.
4. After
determining which systems are allowed to communicate with each other and
granting permission for the two systems to establish a connection, the
_________ provides a one-time session key for that connection.
5. Rather
than building elaborate authentication protocols at each server, _________
provides a centralized authentication server whose function is to authenticate
users to servers and servers to users.
6. A
__________ server issues tickets to users who have been authenticated to the
authentication server.
7. A
__________ is a set of managed nodes that share the same Kerberos database
which resides on the Kerberos master computer system that is located in a
physically secure room.
8. Kerberos
version 5 defines all message structures by using __________ and Basic Encoding
Rules (BER), which provide an unambiguous byte ordering.
9. The
technical deficiencies of Kerberos version 4 are: double encryption, PCBC encryption,
session keys and __________ .
10. A
_________ is the client’s choice for an encryption key to be used to protect
this specific application session.
11. A
_________ consists of a public key plus a user ID of the key owner, with the
whole block signed by a trusted third party which is typically a CA that is
trusted by the user community.
12. __________
defines a framework for the provision of authentication services by the X.500
directory to its users and defines alternative authentication protocols based
on the use of public-key certificates.
13. The
_________ exentsion is used only in certificates for CAs issued by other CAs
and allows an issuing CA to indicate that one or more of that issuer’s policies
can be considered equivalent to another policy used in the subject CAs domain.
14. With
a principal objective of enabling secure, convenient and efficient acquisition
of public keys, __________ is the set of hardware, software, people, policies,
and procedures needed to create, manage, store, distribute, and revoke digital
certificates based on asymmetric cryptography.
15. __________
is a process where authentication and permission will be passed on from one
system to another, usually across multiple enterprises, thereby reducing the
number of authentications needed by the user.
Chapter 4: Key Distribution and User Authentication
TRUE OR FALSE
16. T
17. F
18. T
19. F
20. T
21. F
22. T
23. F
24. T
25. T
26. F
27. T
28. F
29. T
30. T
MULTIPLE CHOICE
16. A
17. A
18. D
19. A
20. C
21. C
22. A
23. C
24. A
25. D
26. B
27. C
28. D
29. A
30. C
SHORT ANSWER
1. key
distribution
2. lifetimsession
key
3. key
distribution center (KDC)
4. Kerberos
5.
ticket-granting
6. Kerberos
realm
7. Abstract
Syntax Notation One (ASN.1)
8. password
attacks
9. subkey
10. (public-key)
certificate
11. 509
12. policy
mappings
13. public-key
infrastructure (PKI)
14. Federation
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