Exploiting Key Space Vulnerabilities in the Physical World (Presentation)
Bill Graydon demonstrates applying information theory and entropy reduction to derive physical building master keys from partial impressions.
Summary
Information Theory in Physical Master Key Systems
Pin-tumbler master key systems rely on geometric key bittings to balance user access, but mathematical relationships between keys leak entropy about the system architecture.
Applying Entropy and Key Space Cryptanalysis
Bill Graydon demonstrates how comparing just a few employee office keys allows calculating the exact bitting parameters of the building master key without picking a single lock.
Impressioning and Decoding Pin Stacks
Combining physical lock impressioning techniques with information-theoretic reduction algorithms drastically reduces the search space needed to cut a functional master key.
Designing Secure Master Key Hierarchies
Graydon presents defensive key management guidelines and mathematical validation models for locksmiths and physical security engineers to eliminate key space leakage.
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