Q.1
RC5 encryption uses Right shift and decryption uses Left shift.
  • a) True
  • b) False
Q.2
The below round is the last step in encryption /decryption in RC5.
Questioncryptography-network-security-questions-answers2.jpg
  • a) True
  • b) False
Q.3
The code bellow is the RC5 encryption pseudo code in C language.
  • a) The left shift operation (should be right shift)
  • b) The right shift operation (should be left shift)
  • c) LEi-1 and REi-1 should be LEi and REi
  • d) The for loop runs from 1 to r-1 ( not 1 to r)
Q.4
“RC5 uses the Feistel Structure.”
  • a) True
  • b) False
Q.5
Find the error in the Decryption pseudo code for RC5 –
  • a) B= RD0 + S [1];
  • b) for i = 1 to r do
  • c) LDi-1 = ((LDi – S [2xi] >>> RDi-1) ⊕ RDi-1);
  • d) A = LD0 – S [0];
Q.6
Which one of the following is not a RC5 mode of operation?
  • a) RC5 block cipher
  • b) RC5-Cipher Block Chaining
  • c) RC5-Cipher Padding
  • d) RC5-CipherText Stealing
Q.7
Which RC5 mode will have the ciphertext longer than the plaintext by at most the size of a single RC5 block?
  • a) RC5 block cipher
  • b) RC5-Cipher Block Chaining
  • c) RC5-Cipher Block Chaining Pad
  • d) RC5-CipherText Stealing
Q.8
Which RC5 mode of operation is this?
  • a) RC5 block cipher
  • b) RC5-Cipher Block Chaining
  • c) RC5-Cipher Block Chaining Pad
  • d) RC5-CipherText Stealing
Q.9
Which of these is not a characteristic of block ciphers?
  • a) Variable key length / block size / number of rounds
  • b) Mixed operators, data/key dependent rotation
  • c) Key independent S-boxes
  • d) More complex key scheduling
Q.10
Which one of the following RC4 algorithm not used in?
  • a) SSL
  • b) TLS
  • c) FTP
  • d) WEP
Q.11
Till when was the RC4 algorithm kept a secret?
Questioncryptography-network-security-questions-answers11.jpg
  • a) 1990
  • b) 1992
  • c) 1996
  • d) 1994
Q.12
RC4 algorithm uses the concept of Block Cipher System.
  • a) True
  • b) False
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