2023 1 OBJECTIVE The purpose of this minor assignment is for you to | Assignment Collections

1 OBJECTIVE The purpose of this minor assignment is for you to demonstrate an understanding of the following task: • How OSI X.800 Security Mechanism can be related to Cryptography using the Data Encryption Standard (DES) cryptosystem. MARKING GUIDELINES This assignment marking involves two (2) steps: 1. Determine maximum assignment mark; let x = Turnitin similarity; If x <= 10%, max assignment mark = 10% If x > 10%. max assignment mark = 11% – 10x Note: In addition, if x > 60%, the case may be reported to the School. 2. Subsequently, your write-up is marked on clarity, readability, completeness, logical coherence, conceptual understanding, and DES cryptosystem task analysis. 2 PROBLEM SCENARIO You are to research and investigate the Data Encryption Standard (DES) cryptosystem and the mathematical aspects involved in it. The following extract is taken from Wikipedia: “The algorithm’s overall structure is shown in Figure 1: there are 16 identical stages of processing, termed rounds. There is also an initial and final permutation, termed IP and FP, which are inverses (IP “undoes” the action of FP, and vice versa). IP and FP have no cryptographic significance, but were included in order to facilitate loading blocks in and out of mid-1970s 8-bit based hardware.[22] Figure 1 (next page): 3 Figure 1 4 Before the main rounds, the block is divided into two 32-bit halves and processed alternately; this criss-crossing is known as the Feistel scheme. The Feistel structure ensures that decryption and encryption are very similar processes — the only difference is that the subkeys are applied in the reverse order when decrypting. The rest of the algorithm is identical. This greatly simplifies implementation, particularly in hardware, as there is no need for separate encryption and decryption algorithms. The ? symbol denotes the exclusive-OR (XOR) operation. The F-function scrambles half a…