Game-Based Proof
Game-based proofs are the formal framework of provable security: security definitions and reductions are expressed as a sequence of games between attacker and challenger, with gradual replacement up to indistinguishability.
Purpose
They give cryptographic protocols a structured, verifiable security proof and are the standard method of modern cryptography.
Mechanism
Define a security game G0 (the real scheme) and G1 (ideal/unbreakable); through a chain of intermediate games G0→G1→...→Gn each step replaces part of the scheme, the distinguishing advantage of each replacement is bounded by an assumption, and the bounds sum to the total advantage.
Use cases
- Security proofs of cryptographic protocols
- Encryption scheme analysis
- Formal security verification