SOME GENERAL PRINCIPLES ABOUT SECURITY

Here are certain general principles of security. The principles are valid for any type of threat, such as fire, burglery, stealing of information, inuring program and data om PCs and servers, personal threats and so on. A total security strategy has the following aims.

1. To detect or recognize a threatening object, person or event, and distinguish it from non-threatening objects, persons or events.

2. To recogize what the threateing item aims at doing. Examples can be: Physical damage, personal attack, stealing of goods, stealing of information, destruction of information, disruption of business operation, etc.

3. To avoid a recogized threat to break through is a first objective when a threat has been recogized.. However, this is not allways totally possible within possible costs and practical conditions. Secondary aims are therefore:

4. To have public or private second-line aiding resources standing by, for example security guard companies, police, fire-guards or fire-department, and having means to allarm those resources.

5. To allarm aiding resources before the process off braking through begins. Such allarms should be authomatic if great values are in stake, but it must also be possible to contact them through telephone.

6. To slow down the break-through so long that the aid manages to come to assistance before the break is completed.

7. If the threat manages to break through and effect damage, there should be reserves in place that reduce the consequences of the damage to an affordable level. Reserves can be: Backup of data and programs, reserve computers or other machines, electricity generators, reserve hosting comodities. Instead of having physical resources at the place, contracts with backup delivering companies, and contracts about delivering spare equipment hithin a certain time limit, can be an althernative.

7. As a last line of resistance,  you shoud have adequate insurance coverage, that will replace lost items and profit after damage. Insurance can be expensive. Therefore a full scale insuranse is not necessarily the right thing. However, the insuranse should be of such a scale that you can live along in a comfortable manner. and so that your business can carry along, also after the damage.

There is also an economical side of security. The security system must not be so expensive that it costs more than the averidge cost of expected attacks that it hinders. More precisely: The sum of the security cost pluss the expected damages that are not avoided, should be minimized.

The security measures must be in order, everybody using them must know about them, must know how tu use them and must find them when needed. The measures should also be comprehensive. There should not be any holes in themeasures.  This includes telephone numbers to the police, the fire department, ambulance and engaged securyty guard comapies, Therefore:

1. All security measures must be clearly marked so that they easily are found when needed.

2. Every person must have got instruction in using the security measures.

3. When installed the mesures must be tested and must be retested at regular intervals.

4. People at the plase must have exercises in using the security mesures, where the responce of the people together with the measures themselves are tested.

5. The security measures must cover the whole area of interest.

One must make it clear to anyone planning to brake in or do sabotage that there are measures in place. However, it is usually not wise to indicate for them exactly where the measures, such as detecors an the like are placed.

About electronic detectors in security systems

An allarm system or an authomatic security system must have detectors placed on strategic positions in order to release an allarm or a counteraction. Detectors recognize some physical change in the surroundings and send a signal to the security system if some physical parameter exceeds some value. The system then realeases the alarm or action.

In advanced syetems, the detector may measure values of some parameters all the time and send all values of the parameters to the central unit. The unit then intrepretes the values and releases allarm or action if the values satisfy some set logical criteria.

There are many types of detectors, depending upon what type of physical parameter they recogize or measure.

- Vibration detectors react if there occur vibrations in the surroundings. They are typically used in burglary allarms. A vibration detector is typiclly placed at a door or a window and detect attempts to breake in at an early stage.

- There are detectors that recogize breakage in windows, doors or building contsructions. An example is current lines that causes a current interruption in a surcuit by breakage. This is a common type of detector used in burglary allarms. Such lines are often integrated in windows or doors.

- Infrared detectors measure the amount of infrared radiuation in the surroundings. Usually such detectors are used to detect fire.

- Some detectors recogize changes in the light intensity in a room. A subtype of these detectors have a unit emitting infrared light and fluctuation in the pattern of infrared light is detected.  Such changes can then be interpreted as people in motion in the room and be used in burglary allarms.

- Some detectors recogize the componets in smoke, either smoke particles or gasses.

An example of smole detector is Ionic chamber smoke detectors. These have an electri curcuit where the current must pass an open chamber. Through the chambers alfa-rays emitted from a piece of the redioctive material americium 240 are sent. The rays ionizes the air in the chamber and allow a small current to go through the curcuit. When smoke comes into the chamber, the ions are neutralized by gasses and the current in the circuit is broken.

A photoelectric smoke detector have a light source and a light detector positioned at 90 degrees angle to each other. When smoke enters, the particles in the smoke wil reflect the light and some of it will hit the light detector.

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