The Data Encryption Standard (DES) has a function consists of four steps. Which of the following is correct order of these four steps?

1. Aan expansion permutation, S-boxes, an XOR operation, a straight permutation
2. Ban expansion permutation, an XOR operation, S-boxes, a straight permutation
3. Ca straight permutation. S-boxes, an XOR operation, an expansion permutation
4. Da straight permutation, an XOR operation, S- boxes, an expansion permutation Directions (91-95) Read the following passage and answer the given questions. A flow graph F with entry node (1) and exit node (11) is shown below :

Pick an option to check yourself, or open the answer below.

Show answer & explanation

Correct answer: B. an expansion permutation, an XOR operation, S-boxes, a straight permutation

Explanation

The DES function expands 32 bits to 48 (expansion permutation), XORs with the round key, compresses through the S-boxes, and applies a straight permutation.