Cryptographic concepts Portfolio Assignment

Complete the following tasks in the python programming language. In your documentation you must demonstrate HOW your ciphers operate, i.e. how they take the plaintext and convert it into the ciphertext, and WHAT each of your design choices were. The accompanying documentation should go into more detail answering WHY you made these design choices and discussing the security of your ciphers .

1. Design your own block cipher to encrypt the message X. (10 MARKS) Your block cipher should have a block size of 6 or more and should include elements of confusion, diffusion and key addition along with multiple rounds of encryption. In your documentation: - Explain the structure of your block cipher and how your cipher achieves the properties of confusion and diffusion. (3 marks) - State the mode of operation you used to implement your block cipher and discuss the reasons why you chose this method. (3 marks: 1 mark for mode of operation, 2 marks for discussion of reasoning) - Discuss how you could make your block cipher more secure. (4 marks: 1 mark for each potential item to increase security above and beyond the specification)

The message X is as follows:

 X = “Meet Alice next to the fridge in Building 18 at ECU.”