I'm learning about Feistel Ciphers at the moment, but having issues with the formulae, so I can't move on from it.
Encryption:
- $πΏπΈ_{π+1} = π πΈ_π$
- $π πΈ_{π+1} = πΏπΈ_π \oplus πΉ( π πΈ_π , πΎ_π)$
For the round function $πΉ( π
πΈ_π , πΎ_π)$, could someone advise on what exactly I need to do? Let's say my key is $1197$, what needs to happen in between the brackets, $(π
πΈ_π , πΎ_π)$ , full diagram screenshot attached, thanks.