Tamperproofing

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Tamperproofing is a term sometimes used for a methodology used to hinder, deter or detect unauthorised access to a device or circumvention of a security system.

Since any device or system can be foiled by a person with sufficient knowledge, equipment, time, etc., the term "tamperproof" is a misnomer. Tamper resistance and tamper-evident systems and devices are better terminology.

[edit] Mechanical

Some devices contain non-standard screws or bolts in an attempt to deter access. Examples are telephone switching cabinets (which have triangular bolt heads; a hex socket would therefore fit these) and computer hard drives, which usually have a star-shaped head for the screws, known as Torx heads. Drivers for these heads are commonly available from electronics retailers.

[edit] Electrical

This style of tamper resistance is most commonly found in burglar alarms. Most trip devices (e.g. pressure pads, passive infrared sensors (motion detectors), door switches) use 2 signal wires which, depending on the configuration of the device, are normally open or normally closed. The sensors sometimes need power too and therefore, to simplify cable runs, multi-core cable is used. Whilst 4 cores would normally be enough for the devices which do require power (leaving two spare for those which don't), cable with additional cores can be used. These additional cores can be wired into a special so-called tamper circuit in the alarm system.

Tamper circuits are just like any other zone (in that they can be n.o. or n.c.) with the exception that the system monitors them 24 hours.

Would-be intruders run the risk of triggering the alarm by attempting to circumvent a given device.

Sensors such as movement detectors, tilt detectors, air-pressure sensors, light sensors etc. which might be employed in some burglar alarms might also be used in a bomb to hinder defusal if discovered after being left in an imperfectly concealed location.