Chapter 25 // Exercise 12 - Principles & Practice Using C++

In this exercise I am using Visual Studio 2019 and a modified version of the std_lib_facilities header found here.

Chapter 25 // Exercise 12

Write out the clear text of the example from section 25.5.6.

Github: N/A

Deciphering the text was part of Exercise 1. You can find the code here:

https://github.com/l-paz91/principles-practice/blob/master/Chapter%2025/Exercise%201/Try%20This%20pg973

The deciphered text reads:

The Tiny Encryption Algorithm is one of the fastest and most efficient cryptographic algorithms in existence.

It was developed by David Wheeler and Roger Needham at the Computer Laboratory of Cambridge University.

It is a Feistel cipher which uses operations from mixed (orthogonal) algebraic groups - XOR, ADD and SHIFT in this case.

This is a very clever way of providing Shannon's twin properties of diffusion and confusion which are

necessary for a secure block cipher, without the explicit need for P-boxes and S-boxes respectively.

It encrypts 64 data bits at a time using a 128-bit key. It seems highly resistant to differential

cryptanalysis, and achieves complete diffusion (where a one bit difference in the plaintext will

cause approximately 32 bit differences in the ciphertext) after only six rounds. Performance on a

modern desktop computer or workstation is very impressive.