Symmetric Cryptography

Communication Theory of Secrecy Systems

Claude Shannon

Puts cryptography on a mathematical footing and proves the one-time pad is the only perfectly secret cipher.

Assumes probability, and ideally Shannon's information paper first — this one leans on it throughout

AES Proposal: Rijndael

Joan Daemen & Vincent Rijmen

Specifies the Rijndael block cipher submitted to, and later selected as, the Advanced Encryption Standard, built from simple operations designed explicitly to resist known cryptanalytic attacks.