CC Certified in Cybersecurity (CC)

A lock is a device that prevents a physical structure (typically a door) from being opened, indicating that only the authorized person (i.e. the person with the key) can open it. A fence or a barrier will prevent ALL access. Turnstiles are physical barriers that can be easily overcome (after all, it is common knowledge that intruders can easily jump over a turnstile when no one is watching). 

Clearing is a method used to eliminate the residual physical effects of writing original values to a storage

device. This process involves overwriting the data with zeros or ones to ensure the original data cannot

be retrieved. For example, when a hard disk is erased, all previously stored data is overwritten, making it

impossible to recover the original data (see ISC2 Study Guide, Chapter 5, Module 1).

On the other hand, purging is more rigorous than wiping, in which the storage media is declassified to be

used in a less secure environment. Destruction physically destroys the storage media so it cannot be

used again. Overwriting is used in the wiping process, but it does not remove the remaining physical

effects. It is part of the wiping process, not a stand-alone method.