About this deck
A substitution cipher maps each plaintext letter to a fixed ciphertext letter. Caesar's shift is a special case: c ≡ p + k (mod 26) . Key sections include: MATHEMATICAL CRYPTOGRAPHY; Substitution & the Statistics That Betray It; The One-Time Pad — Unbreakable, Unusable; Modular Arithmetic — Integers, Wrapped; Fermat & Euler — Why RSA Works; RSA (1977) — Factoring as a Trapdoor; Diffie–Hellman — A Secret in Public; Elliptic Curves — Same Idea, Smaller Keys; One-Way: SHA-256 and the Compression Trick; Signing — Authorship Without Disclosure.
catalogmathcryptography