Cryptology ePrint Archive: Report 2002/160

Cryptology and Physical Security: Rights Amplification in Master-Keyed Mechanical Locks

Matt Blaze

Abstract: This paper examines mechanical lock security from the perspective of computer science and cryptology. We focus on new and practical attacks for amplifying rights in mechanical pin tumbler locks. Given access to a single master-keyed lock and its associated key, a procedure is given that allows discovery and creation of a working master key for the system. No special skill or equipment, beyond a small number of blank keys and a metal file, is required, and the attacker need engage in no suspicious behavior at the lock's location. Countermeasures are also described that may provide limited protection under certain circumstances. We conclude with directions for research in this area and the suggestion that mechanical locks are worthy objects for study and scrutiny.

Category / Keywords: applications / applications / locks; rights amplification; novel applications of cryptanalysis; related key attacks;

Date: received 22 Oct 2002, last revised 16 Feb 2003

Contact author: mab at crypto com

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Revised final version (6 February 2003)

Version: 20030216:175626 (All versions of this report)

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