Q. Which of the following can be classified under advantages and disadvantages of OFB mode?

i) Transmission errors
ii) A bit error in a ciphertext segment
iii) Cannot recover from lost ciphertext segments
iv) Ciphertext or segment loss

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Q. In OFB Transmission errors do not propagate: only the current ciphertext is affected, since keys are generated “locally”.

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Q. Which of the following modes does not implement chaining or “dependency on previous stage computations”?

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Q. The counter value in CTR modes repeats are a regular interval.

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Q. Which mode of operation has the worst “error propagation” among the following?

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Q. Which block mode limits the maximum throughput of the algorithm to the reciprocal of the time for one execution?

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Q. Which mode requires the implementation of only the encryption algorithm?

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Q. Which of the following modes of operation does not involve feedback?

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Q. Which of the following is a natural candidates for stream ciphers?

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Q. The XTS-AES mode was approved by NIST in

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Q. The XTS-AES mode is based on the concept of tweakable block cipher.

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Q. The purpose of a ‘tweak’ in XTS-AES mode is to

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Q. A tweak is used in XTS-AES mode to provide a different output for the same input PT and same key.

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Q. XTS-AES mode of operation is a better version of

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Q. What is the size of the XTS-AES key?

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Q. Which of the following represent the tweak?

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Q. Which of the following is true for the tweak in XTS-AES mode?

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Q. Which of the following is the correct encryption statement representation for the XTS-AES mode?

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Q. The last two blocks of the XTS-AES mode are –

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