Symmetric key cryptography substitution cipher:substituting one thing for another o monoalphabetic cipher:substitute one letter for another plaintext:abcdefghijklmnopqrstuvwxyz ciphertext:mnbvcxzasdfghjklpoiuytrewq E.g.:plaintext:bob.i love you.alice ciphertext:nkn.s gktc wky.mgsbc Q:How hard to break this simple cipher?: brute force (how hard?) ▣other? 8:Network Security 8-108: Network Security 8-10 Symmetric key cryptography substitution cipher: substituting one thing for another  monoalphabetic cipher: substitute one letter for another plaintext: abcdefghijklmnopqrstuvwxyz ciphertext: mnbvcxzasdfghjklpoiuytrewq Plaintext: bob. i love you. alice ciphertext: nkn. s gktc wky. mgsbc E.g.: Q: How hard to break this simple cipher?: ❑ brute force (how hard?) ❑ other?