MonoAlphabetic Cipher

What is a MonoAlphabetic Cipher?

MonoAlphabetic Cipher replaces each letter with a unique letter using a fixed substitution.

How the key looks like?

Plain:      ABCDEFGHIJKLMNOPQRSTUVWXYZ
Cipher:    QWERTYUIOPASDFGHJKLZXCVBNM

Let's encrypt "HELLO":

   • H → I (find H in plain, get corresponding cipher letter)
   • E → T
   • L → S
   • L → S
   • O → G

Result: HELLO → ITSSG