Cryptography Applied Engineering

Applied cryptography is taking cryptographic algorithms (AES, RSA, ECDSA, SHA-256) and using them correctly to solve real security problems: encrypting data at rest, authenticating messages, securing key exchange, signing documents. Core areas: symmetric encryption (fast, shared key), asymmetric encryption (slow, public-key), hashing (one-way, for integrity), key derivation (derive keys from passwords), authenticated encryption (encryption + authentication combined).