Q. What is the number of iterations required in total to generate all the sub-keys in blowfish?

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Q. A single blowfish s-box converts 8-bits to _________ bits.

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Q. The 32bit output of s-box 1 is XORed with s-box 2.

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Q. Which of the following statements are true with respect to the blowfish algorithm –

i) Provided key is large enough, brute-force key search is not practical, especially given the high key schedule cost
ii) Key dependent S-boxes and sub keys make analysis very difficult
iii) Changing both halves in each round increases security
iv) Blowfish has improved avalanche effects

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Q. Which of the following is true for the RC5 algorithm?

i) Has variable number of rounds
ii) Has fixed Key length
iii) High memory Requirements
iv) Uses only primitive computational operations commonly found on microprocessors

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Q. What are the allowable values of word size in bit for RC5 algorithm?

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Q. The number of rounds in RC5 can range from 0 to _____________

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Q. The standard/nominal version of the RC5-w/r/b has parameters w/r/b as

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Q. The total number of subkeys t used in the RC5 algorithm is given by the formula (r corresponds to number of rounds)

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Q. RC5 uses 2 magic constants to define their subkeys. These are

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Q. The value of the base of natural logarithms is

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Q. The value of the golden ratio is

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Q. Calculate the number of subkeys required in RC5 for 18 rounds of computation.

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Q. RC5 encryption uses Right shift and decryption uses Left shift.

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Q. “RC5 uses the Feistel Structure.”

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Q. Which one of the following is not a RC5 mode of operation?

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Q. Which RC5 mode will have the ciphertext longer than the plaintext by at most the size of a single RC5 block?

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Q. Which of these is not a characteristic of block ciphers?

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Q. Which one of the following RC4 algorithm not used in?

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Q. Till when was the RC4 algorithm kept a secret?

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