Security analysis of a widely deployed locking system

Electronic locking systems are rather new products in the physical access control market. In contrast to mechanical locking systems, they provide several convenient features such as a more flexible access rights management, the pos- sibility to revoke physical keys and the claim that electronic keys can not be cloned as easily as their mechanical coun- terparts. Features like these make electronic locking sys- tems especially attractive to office and industry buildings with many locks and keys being used. For such buildings, situations like the necessity to grant custom-tailored access rights to individuals, the danger of key loss or the fluctua- tion of employees often cannot be handled with conventional locking systems than with electronic ones. While for some electronic locks, mechanical flaws had been found [1], only few publications analyzed the cryptographic security of elec- tronic locking systems. [2] In this paper, we analyzed the electronic security of an electronic locking system which is widely deployed in the field. While we consider the system to be well-designed, we discovered some implementation flaws which eventually allow the generation of a system-wide mas- ter key by either having physical access to any key in the system or by intercepting two door opening procedures