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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Scaling of the existing bits
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Duplication of the existing bits
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Addition of zeros
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Addition of ones
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Detailed explanation-1: -The input is 32 bits. This input is first expanded to 48 bits (permutation plus an expansion), that involves duplication of 16 of the bits. Explanation: There are 64 bits to permute and this requires a 8×8 matrix.
Detailed explanation-2: -During expansion permutation, the RPT is diffuse from 32 bits to 48 bits. It can be enhancing the bit size from 32 to 48, the bits are permuted as well known as the expansion permutation.
Detailed explanation-3: -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-4: -The block size in DES is 64 bits. The cipher key size is 56 bits. The round key size is 48 bits.
Detailed explanation-5: -DES works by encrypting groups of 64 message bits, which is the same as 16 hexadecimal numbers. To do the encryption, DES uses “keys” where are also apparently 16 hexadecimal numbers long, or apparently 64 bits long. However, every 8th key bit is ignored in the DES algorithm, so that the effective key size is 56 bits.