warded lock

A warded lock is a type of lock that uses "wards" for security. Wards are projections inside the lock that surround the keyhole. These projections prevent a plain key from turning. To open a warded lock, the key must have slots that align with these wards, allowing it to pass through and turn the bolt.12

The Romans introduced wards into lock design, and for centuries, this was the primary method for securing locks. While effective against simple keys, warded locks have always been relatively easy to pick because instruments can be designed to bypass the wards. The first known example of a lock, found in ancient Nineveh, was a pin tumbler lock, which predates the widespread use of wards.12