Playfair Cipher Cryptanalysis: https://github.com/yehezkiel1086/crypto-docs
Classical Ciphers: https://github.com/yehezkiel1086/crypto-docs/tree/main/college/classical-ciphers
Cryptohack Writeups: https://github.com/yehezkiel1086/crypto-docs/tree/main/crypt-h-writeup