CRY Review + Solution

A ________ cipher replaces one character with another character. A) substitution B) transposition C) round D) None of the mentioned

A

A combination of an encryption algorithm and a decryption algorithm is called a ________. A) cipher B) secret C) key D) None of the mentioned.

A

A modern cipher is usually a complex _____cipher made of a combination of different simple ciphers. A) round B) circle C) square D) None of the mentioned.

A

A(n) ______ is a keyless substitution cipher with N inputs and M outputs that uses a formula to define the relationship between the input stream and the output stream. A) S-box B) P-box C) T-box D) None of the mentioned.

A

A(n) _______ algorithm transforms plaintext to ciphertext A) encryption B) decryption C) Quadruple D) None of the mentioned.

A

Cryptanalysis is used A) to find some insecurity in a cryptographic scheme B) to increase the speed C) to encrypt the data D) None of the mentioned.

A

DES is a(n) ________ method adopted by the U.S. government. A) symmetric-key B) asymmetric-key C) public-key D) None of the mentioned.

A

ECB and CBC are ________ ciphers. A) block B) stream C) field D) None of the mentioned

A

In a(n) ________ cipher, the same key is used by both the sender and receiver. A) symmetric-key B) asymmetric-key C) public-key D) None of the mentioned.

A

In a(n) ________, the key is called the secret key. A) symmetric-key B) asymmetric-key C) public-key D) None of the mentioned.

A

In an asymmetric-key cipher, the receiver uses the ______ key to decrypt ciphertext A) private B) public C) pre-shared key D) None of the mentioned.

A

On which hard mathematical problem does RSA base its security? A) Factorization of big numbers B) Finding big prime numbers C) Multiplication of big prime numbers D) Exponentiation of big numbers

A

The ________ is the message after transformation. A) ciphertext B) plaintext C) secret-text D) None of the mentioned.

A

The ________ method provides a one-time session key for two parties. A) Diffie-Hellman B) RSA C) DES D) AES

A

The _________ attack can endanger the security of the Diffie-Hellman method if two parties are not authenticated to each other. A) man-in-the-middle B) ciphertext attack C) plaintext attack D) None of the mentioned

A

The term keystream is usually connected with A) stream ciphers B) block ciphers C) public-key ciphers D) key-exchange protocols

A

Today, many Internet businesses and users take advantage of cryptography based on this approach. A) public key infrastructure B) output feedback C) Encrypting File System D) single signon

A

What is data encryption standard (DES)? A) block cipher B) stream cipher C) bit cipher D) None of the mentioned.

A

________ is the science and art of transforming messages to make them secure and immune to attacks. A) Cryptography B) Cryptoanalysis C) Cryptography AND Cryptoanalysis D) None of the mentioned.

A

_________ ciphers can be categorized into two broad categories: monoalphabetic and polyalphabetic. A) Substitution B) Transposition C) round D) None of the mentioned.

A

::Unit 01 - Q005:: A(n) ______ algorithm transforms ciphertext to plaintext. A) encryption B) decryption C) Quadruple D) None of the mentioned.

B

A(n) _______is a keyless transposition cipher with N inputs and M outputs that uses a table to define the relationship between the input stream and the output stream. A) S-box B) P-box C) T-box D) None of the mentioned.

B

AES has _____ different configurations A) two B) three C) four D) five

B

DES uses a key generator to generate sixteen _______ round keys. A) 32-bit B) 48-bit C) 54-bit D) 42-bit

B

DES was designed to increase the size of the DES key A) Double B) Triple C) Quadruple D) None of the mentioned.

B

In a(n) ________ cipher, a pair of keys is used. A) symmetric-key B) asymmetric-key C) public-key D) None of the mentioned.

B

In an asymmetric-key cipher, the sender uses the__________ key to encrypt plaintext A) private B) public C) All of the mentioned answers D) None of the mentioned.

B

In asymmetric key cryptography, the private key is kept by A) sender B) receiver C) sender and receiver D) all the connected devices to the network

B

In the symmetric key cryptography both sender and receiver posses ______ A) Different keys. B) Same key. C) Public key. D) None of the mentioned.

B

Substitution ciphers. A) The order of plaintext letters is rearranged during encryption. B) Letters of the plaintext messages are replaced with other letters during the encryption. C) Exponentiation of big numbers D) None of the mentioned.

B

The Diffie-Hellman key exchange protocols needs ___ messages to finish key exchange. A) 1 B) 2 C) 3 D) 4

B

The Playfair Cipher uses a matrix of size A) 4 x 4 B) 5 x 5 C) 6 x 6 D) 7 x 7

B

The ________ cipher reorders the plaintext characters to create a ciphertext. A) substitution B) transposition C) round D) None of the mentioned.

B

The ________is the original message before transformation. A) ciphertext B) plaintext C) secret-text D) None of the mentioned

B

This is the name for the issuer of a PKI certificate. A) man in the middle B) certificate authority C) Resource Access Control Facility D) script kiddy

B

Use Caesars Cipher to decipher the following: HQFUBSWHG WHAW A) ABANDONED LOCK B) ENCRYPTED TEXT C) ABANDONED TEXT D) ENCRYPTED LOCK

B

What risks arise when using the same key to encrypt both directions of a communication channel, that are not present if using different keys for the different directions? A) Message tampering by flipping bits in the ciphertext. B) Reflection attacks. C) Hash collisions. D) Eavesdropping attacks.

B

DES has an initial and final permutation block and _________ rounds. A) 14 B) 15 C) 16 D) None of the mentioned.

C

One commonly used public-key cryptography method is the ______ algorithm. A) DES B) RC4 C) RSA D) AES

C

S-boxes in DES map A) 2 to 4 bits B) 4 to 4 bits C) 6 to 4 bits D) 4 to 6 bits

C

The Caesar cipher is a _______cipher that has a key of 3. A) transposition B) additive C) shift D) None of the mentioned.

C

The DES function has _______ components. A) 2 B) 3 C) 4 D) 5

C

The _______ cipher is the simplest monoalphabetic cipher. It uses modular arithmetic with a modulus of 26. A) transposition B) additive C) shift D) None of the mentioned.

C

The _______ is a number or a set of numbers on which the cipher operates. A) cipher B) secret C) key D) None of the mentioned.

C

This is an encryption/decryption key known only to the party or parties that exchange secret messages. A) e-signature B) digital certificate C) private key D) security token

C

When trying to crack a code using by trying all the possibilities, this method is known as ____________. A) Caesar cipher. B) Cyberspace C) Brute force attack D) Vegineer cipher

C

Which one of the following algorithm is not used in asymmetric-key cryptography? A) rsa algorithm B) diffie-hellman algorithm C) electronic code book algorithm D) None of the mentioned.

C

Which two important issues are addressed with public-key cryptography A) Production of big prime numbers and their multiplication B) Factorization of natural numbers and discrete logarithm problem C) Key distribution and Digital signatures D) Production of master and session keys

C

In a known plaintext attack the attacker knows A) predetermined selected ciphertext B) one plaintext and one key C) one ciphertext and one key D) plaintext and ciphertext

D

What is the biggest advantage of CBC mode of operation A) It can encrypt in parallel different parts of the messages B) It does not need Initialization Vector (IV) C) The Initialization Vector (IV) is secret � so the length of the secret key is doubled D) A ciphertext block depends on all blocks before it

D

______ is a round cipher based on the Rijndael algorithm that uses a 128-bit block of data. A) DES B) 3DES C) RC4 D) AES

D