On this site I talk about a number of different security measures. Just as in my discussion of attacks and attackers it is important to have a firm understanding of security measures and exactly what type of security each provides. . . and does not provide.
Though many, including me, view an alarm as a serious security upgrade it is important to realize that it does not actually make your home more difficult to get into. An alarm is merely a detective security measure; that is, it makes your home more difficult to get into undetected. There are three categories of security measures: deterring, delaying, and detective. Alternatively these categories can be thought of as “before” (deterring), “during” (delaying), and “after” (detective) security measures, based on what stage of an attack with are intended to address.
Category I: Deterring Measures.
Deterrents are those security measures that play a role before the attack is even attempted (i.e. during the reconnaissance phase of an organized attack). Deterring security measures deter the attack from even attempting the breach by making him or her re-think your defenses in comparison to risk of compromise and his or her ability. Security measures in this category often include signs or stickers indicating the presence of an alarm, visible security cameras, etc. Other deterring measures include motion lights, visible cameras, signs warning of alarm systems and dogs, and routine police patrols.
Deterring security measures are difficult to quantify in the digital security realm, but they exist. A password prompt for a full-disk encrypted computer may serve as a deterrent to an attacker, as may a passcode on a smartphone.
Category II: Delaying Measures
Delaying devices are those devices that play a role during the breach attempt. Locks cannot make your home impossible to get into, but they can make the task take an unacceptably long time especially if the attack is intended to go undetected. Items in this category include locks, fences, anti-shatter window film, etc., all of which are intended to slow an attacker’s progress during the breach. In some cases delaying devices may exceed an attacker’s skill level and force him to move on to an easier target.
Delaying measures are the ones the average user primarily employs on the digital perimeter. These measures include strong encryption of data-at-rest using file-level and full-disk encryption on computers, encryption of data-in-transit using HTTPS and a VPN and ensuring your Wi-Fi is encrypted, and the use of good, strong passwords.
Category III: Detective Measures
Detective security devices are the “after” measures, the ones that alert you that a breach is in progress or has already occurred or been attempted. Devices in this category include intrusion detection systems (alarms) and surveillance cameras. The presence of these types of devices may have the added benefit of serving as Category 1 security measures, but this is generally not their primary purpose. In addition to alerting us to the breach or breach attempt, Category 3 security measures can also capture images of the attacker, alert police or security, and, if overt, place severe limitations on the amount of time an attacker is willing to spend “on target”. A good example of Category III measures in the digital world are event logs.
There is some degree of overlap in these categories and you should understand exactly what benefits a given security measure provides when considering your perimeter. A high security lock is a good example of a security measure serving in multiple categories. The lock is certainly primarily intended as a Category II security measure. Because of the novel mechanisms and tight manufacturing tolerances common to high security locks it would be extremely difficult to pick or otherwise defeat covertly, delaying the attack and forcing the attacker to spend a great deal of time exposed during this process.
This simple fact alone may also place it in Category I. An intruder who notices the lock may decide it is simply too difficult to defeat (and wonder what other security measures you have) and move on. On the other hand, if the attacker is sufficiently determined to enter your home, he may make the decision to simply kick in the door or break a window. This would place the lock indirectly into Category III, as you would immediately notice a kicked-in door or broken window and know someone had been in your home. This is the chief comfort I derive from the high security locks I use: while I fully realize that a burglar could smash a window, I know with a reasonable degree of certainty that no one (except possibly a Level IV attacker) can enter my home without my knowledge.