Cryptography Prep Test

1.	The four modes of DES include all the following except ECB ECC CFB CBC
2.	A type of cipher that replaces bits, characters, or character blocks with alternate bits, characters, or character blocks to produce ciphertext is known as a Permutation cipher Block cipher Transposition cipher Substitution cipher
3.	Which of the following is not an advantage of symmetric key systems? Scalability Speed Strength Availability
4.	The Advanced Encryption Standard (AES) is based on what symmetric key algorithm? Twofish Knapsack Diffie-Hellman Rijndael
5.	A message that’s encrypted with the sender’s private key only, for the purpose of authentication, is known as a(n) Secure message format Signed and secure message format Open message format Message digest
6.	All the following are examples of asymmetric key systems based on discrete logarithms except Diffie-Hellman Elliptic Curve RSA El Gamal
7.	The four main components of a Public Key Infrastructure (PKI) include all the following except Directory Service Certificate Authority Repository Archive
8.	Which of the following Internet specifications provides secure e-commerce by using symmetric key systems, asymmetric key systems, and dual signatures? Public Key Infrastructure (PKI) Secure ElectronicTransaction (SET) Secure Sockets Layer (SSL) Secure HypertextTransfer Protocol (S-HTTP)
9.	The minimum number of SAs required for a two-way IPSec session between two communicating hosts using both AH and ESP is 1 2 4 8
10.	An IPSec SA consists of the following parameters, which uniquely identify it in an IPSec session, except: Source IP Address Destination IP Address Security Protocol ID Security Parameter Index (SPI)

Answers

1.	B. ECC. ECC is the Elliptic Curve cryptosystem, an asymmetric algorithm. ECB (Electronic Code Book), CFB (Cipher Feedback), CBC (Cipher Block Chaining), and OFB (Output Feedback) are all valid DES modes of operation. Review “Data Encryption Standard (DES).”
2.	D. Substitution cipher.Transposition ciphers and permutation ciphers rearrange data to produce ciphertext. A block cipher is a type of cipher that operates on a block of data. Review “Types of ciphers.”
3.	A. Scalability. Symmetric key systems aren’t scalable because of the difficulty of key management between individual pairs of communicating parties. Review “Symmetric key cryptography.”
4.	D. Rijndael.The Rijndael Block Cipher has been selected as the AES.Twofish was a finalist for the AES standard but wasn’t selected. Knapsack and Diffie-Hellman are asymmetric key systems. Review “Rijndael Block Cipher.”
5.	C. Open message format. A secure message is encrypted with the receiver’s public key to achieve confidentiality. A signed and secure message is encrypted with both the receiver’s public key and the sender’s private key. A message digest is produced by a one-way hashing function to digitally sign a message for authentication. Review “Asymmetric key cryptography.”
6.	C. RSA. RSA is based on factoring large prime numbers. Review “RSA.”
7.	A. Directory Service.The four basic components of a PKI are the Certificate Authority (CA), Registration Authority (RA), Repository, and Archive. Review “Public Key Infrastructure (PKI).”
8.	B. Secure ElectronicTransaction (SET). Only SET implements the concept of dual signatures for authentication. Review “Internet Security Applications.”
9.	C. Four Security Associations (SAs) are required because SAs are simplex (one-way) and an SA is required for each protocol. Review “IPSec.”
10.	A. Source IP Address.The Source IP Address isn’t included in an SA. Review “IPSec.”