Modern Cryptography
The canonical five primitives that founded the modern era — plus the wider landscape they unlocked
The earlier halls distinguish cryptanalytic breaks, operational misuse, obsolescence, and unresolved systems; a correctly used one-time pad remains unbreakable. The five primitives here serve different purposes. DES and AES are symmetric block ciphers; DES is now unsafe because its 56-bit key is too small. RSA supports distinct public-key encryption and signature schemes, with appropriate encoding and padding such as OAEP and PSS. Diffie–Hellman is key agreement, and SHA-256 is a hash function. These building blocks explain encryption, shared-secret establishment, signatures, and integrity; none alone provides a complete secure system.
For the broader landscape — ChaCha20, ECDH, post-quantum standardisation, and the cipher-vs-protocol taxonomy — see the Modern Cryptography wing. For the design rule that underpins every card in this hall, see Kerckhoffs's Principle.
DES was standardized in 1977. Its 56-bit key became vulnerable to practical exhaustive search, demonstrated by EFF’s Deep Crack in 1998.
Diffie–Hellman derives a shared group element over a public channel. Authentication, appropriate groups and key derivation are needed for secure protocol use.
RSA uses a public modulus and exponents to support public-key constructions. Secure encryption and signatures need specified padding, adequate parameters and correct implementation.
AES (2001) — the cipher that encrypts the modern world; chosen by open competition, scrutinised for two decades, still without a practical attack.
SHA-256 (2002) — a 256-bit fingerprint for any input; the verification engine of Git, Bitcoin, TLS certificates, and software integrity worldwide.
ECDSA (1992) — signing with elliptic curves, and the one-line mistake that handed Sony's PlayStation 3 master key to the world.
Shamir's Secret Sharing (1979) — split a secret so any k of n holders can rebuild it and any k−1 learn absolutely nothing.
Zero-knowledge proofs (1985) — convince someone a statement is true while revealing nothing beyond its truth. Run the Schnorr protocol and its simulator.
The museum’s closing lesson: Modern cryptography specifies security goals, attack models and assumptions. Public designs, suitable parameters and careful implementations matter together. Historical weaknesses do not imply that every classical system is broken, or that modern primitives are secure under every use.