CISSP Practice Questions & Answers
Which of the following are NOT operating modes of the DES encryption algorithm?
A) CBC
B) ECB
C) CFB
D) OFB
E) CBE
(Ans- e.
DES has four modes of operations:
CBC - Cipher Block Chaining. In CBC mode, each plaintext block is XORed with the previous cipher text block and then encrypted.
ECB - Electronic Code Book. In ECB mode, each plaintext block is encrypted independently with the block cipher.
CFB - Cipher Feedback. In CFB mode, the previous cipher text block is encrypted and the output produced is combined with the plaintext block using XOR to produce the current cipher text block.
- / 4
OFB - Output Feedback. OFB mode is similar to CFB mode except that the quantity XORed with each plaintext block is generated independently of both the plaintext and cipher text. Which formula can be used to calculate the Annualized Loss Expectancy (ALE)?
- SLE (Single Loss Expectancy) + ARO (Annualized Rate of Occurrence)
- Asset Value * EF (Exposure Factor)
- Asset Value * EF (Exposure Factor) * ARO (Annualized Rate of
Occurrence)
- SLE (Single Loss Expectancy) * ARO (Annualized Rate of Occurrence) *
Asset Value (Ans- c; Which of the following protocols can be used to translate a physical address, such as an Ethernet address, into a logical IP address?
A) ARP
B) PPP
C) RARP
D) ICMP
E) SLIP
(Ans- c
RARP (Reverse Address Resolution Protocol) is a protocol that can be used to translate a physical address, such as an Ethernet address, into an IP address. RARP is commonly used by diskless workstations, which often only know their hardware interface addresses when booted. They must 2 / 4
discover their IP addresses from an external source, such as a RARP server. In this case, the host broadcasts its physical address and a RARP server replies with the host's IP address.
On the other hand, ARP (Address Resolution Protocol) is a network layer protocol used to convert an IP address into a physical address, such as an Ethernet address. A host wishing to obtain a physical address broadcasts an ARP request onto the network. The host on the network that has the IP address in the request then replies with its physical hardware address.
On the other hand, ICMP (Internet Control Message Protocol) is a message control and error-reporting protocol that uses IP datagrams. In contrast, SLIP and; Which of the following statements are true regarding cryptography?
- The Diffie-Helman algorithm takes a message of arbitrary length and
generates a 128-bit message digest
- The strength of a RSA public key encryption is based on the difficulty of
finding the discreet logarithm in a finite field
- In a digitally signed message, the entire message is encrypted using the
public key of the sender
- The RC5 algorithm is a method where subjects exchange secret keys
over a non-secure mediu (Ans- e.
- / 4
The strength of a RSA public key encryption is based on the difficulty of factoring the product of large prime numbers, and NOT based on the difficulty of finding the discreet logarithm in a finite field. The RSA algorithm can be used for encryption, key exchange, and digital signatures.
The MD5 algorithm, not the Diffie-Hellman algorithm, is a message digest algorithm that takes a message of arbitrary length and generates a 128-bit message digest. On the other hand, the Diffie-Hellman key exchange is a method where subjects exchange secret keys over a non-secure medium without exposing the keys.
Lastly, in a digital signed message, only the message digest is encrypted using the private key of the sender. The entire message is NOT encrypted and the public key is NOT used by the sender to encrypt the data . Which of the following is NOT addressed by the Clark-Wilson Integrity Model?
- Procedures that take the system from one valid state to another
- Procedures that test the constrained data items to conform to integrity
constraints
- Data not subject to integrity controls
- Data subject to integrity controls
- Procedures that prevent a subject at a lower level of integrity from
invoking a subject at a higher level of integrity (Ans- e.
The Clark-Wilson model involves two primary elements for achieving data integrity — the well-formed transaction and separation of duties. Well-
- / 4