COMPUTER ETHICS AND SECURITY
CRYPTOGRAPHY AND ENCRYPTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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8
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4
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6
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12
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Detailed explanation-1: -The DES (Data Encryption Standard) algorithm is a symmetric-key block cipher created in the early 1970s by an IBM team and adopted by the National Institute of Standards and Technology (NIST). The algorithm takes the plain text in 64-bit blocks and converts them into ciphertext using 48-bit keys.
Detailed explanation-2: -The total number of exclusive-or operations is 16 × 2 = 32, because each round uses two exclusive-or operations (one inside the function and one outside of the function).
Detailed explanation-3: -Explanation: The substitution consists of a set of 8 S-boxes, each of which accepts 6 bits as input and produces 4 bits as output.
Detailed explanation-4: -After the compressed key is XORed with the expanded block, the 48-bit result moves to a substitution operation. The substitutions are performed by eight substi-tution boxes, or S-boxes.