# Understanding Cryptography by Christof Paar and Jan Pelzl - Chapter 4 Solutions - Ex4.15

- 2 mins- Return to index
- Exercise 4.1
- Exercise 4.2
- Exercise 4.3
- Exercise 4.4
- Exercise 4.5
- Exercise 4.6
- Exercise 4.7
- Exercise 4.8
- Exercise 4.9
- Exercise 4.10
- Exercise 4.11
- Exercise 4.12
- Exercise 4.13
- Exercise 4.14
- Exercise 4.15
- Exercise 4.16

## Exercise 4.15

*Derive* the bit representation for the following round constants within the key schedule:

- RC[8]
- RC[9]
- RC[10]

### Solution

*This solution is verified as correct by the official Solutions for Odd-Numbered Questions manual.*

Starting from , where is the AES polynomial.

As such, the first 10 RC values are as follows:

After 8 is where the reduction polynomial comes into play to bring the result back into the field.

I wrote a python script which can calculate any number of RC constants (This uses the Mod2Polynomial class I created for another exercise):