Lockpicking has become a popular topic with many in the security community.
This title addresses the topics of impressioning, master key escalation, skeleton keys.
It focuses on locks in use as well as ones that have emerged on the market.
Litera
Elefant
Syngress Media,u.s. Keys to the kingdom. impressioning, privilege escalation, bumping, and other key-based attacks against physical locks, paperback/deviant ollam