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Represents the total number of possible values of keys in a cryptographic algorithm or other security measure, such as a password.
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Question 206 - 212-81 discussion

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What does Output feedback (OFB) do:

A.
The message is divided into blocks and each block is encrypted separately. This is the most basic mode for symmetric encryption
Answers
A.
The message is divided into blocks and each block is encrypted separately. This is the most basic mode for symmetric encryption
B.
The cipher text from the current round is XORed with the plaintext from the previous round
Answers
B.
The cipher text from the current round is XORed with the plaintext from the previous round
C.
A block cipher is converted into a stream cipher by generating a keystream blocks, which are then XORed with the plaintext blocks to get the ciphertext
Answers
C.
A block cipher is converted into a stream cipher by generating a keystream blocks, which are then XORed with the plaintext blocks to get the ciphertext
D.
The cipher text from the current round is XORed with the plaintext for the next round
Answers
D.
The cipher text from the current round is XORed with the plaintext for the next round
Suggested answer: C

Explanation:

A block cipher is converted into a stream cipher by generating a keystream blocks, which are then XORed with the plaintext blocks to get the ciphertext

https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Output_feedback_(OFB)

The output feedback (OFB) mode makes a block cipher into a synchronous stream cipher. It generates keystream blocks, which are then XORed with the plaintext blocks to get the ciphertext. Just as with other stream ciphers, flipping a bit in the ciphertext produces a flipped bit in the plaintext at the same location. This property allows many error-correcting codes to function normally even when applied before encryption.

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asked 18/09/2024
Muhammad Imran Khan
35 questions
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