In the paranoid world of Neon Twilight, security systems have become not only the frontline against human intruders but also a necessary defence against parasitic creatures and noxious diseases. Although palmprint readers and passcards are still used for primitive systems, the use of Iriscans, Biometric Scanners, Life Detectors and DNA-readers has become ubiquitous in the Advanced nations for important areas. Given the efficiency of these systems, intrusion has become increasingly more difficult unless one employs expensive counter-measures. The following systems and counter-measures are in general use in 2038:

Life Detectors are the most significant development in both military and personal security, for they actually detect life-signs at distances of up to 50 metres, even through walls and other obstacles. Their versatility has useful applications in tracking and hunting, but their expense and bulk (each device weighs about 40 kilos) makes them portable only on vehicles. Life Detectors are used only in the most sensitive sites. The image from an LD is usually blurry, and animals of approximately the same size as a human can fool the sensor. Countermeasures: unfortunately none. Certain types of material, such as lead, can shield the person, but Life-shields are even rarer and more expensive since they are used only by military Special Forces.

Biometric scanners perform a micron-level scan of a person's body, especially the facial features, and then compare with a smart adaptive image in the databank. Changes in weight, glasses, broken noses and such are corrected-for by the scanner. The bio-scanner also samples a person's genetic code from the particles floating around the body and compares it to the databank in microseconds. Bio-scanners are non-intrusive - a person walking through a security gate is not even slowed down during the procedure, and probably won't notice it. Doppelganger Skins were invented to bypass biometric scanners : the skin is grown from the DNA of an approved employee from the databank and molded to conform to the person's physical features. This is, of course, an expensive and time-consuming process, and will only last for about a day before deformities in the 'skin' develop and are noticed by biometrics.

Keypads and cardlocks are generally considered as obsolete as circuit-break alarms, but magnetic locks are still used by the general populace the way TwenCen people used Yale locks. Maglocks require a proper passkey, usually in combination with another security system. Bypassing either device does not require a Photonics roll; a Security roll will suffice.

Iris-scanners were an excellent security system about twenty years, when few people had the necessary genegineering skills to grow a cloned iris on short order. Nowadays such operations are common on the black market, and Iriscans are no longer the cutting edge. Iriscans rely on a weak laser to scan the iris of a person's eye. An iris has more than 250 discrete unique elements, as opposed to only about 35 for fingerprints, and an iris does not change over the course of a lifetime, a significant advantage in areas (such as executive suites) where non-intrusive polite systems are required. Iriscans are the most reliable system (1 in 1 million chance of error), and are used in areas where mistakes are unacceptable.

Sniffers take millions of air-samples from around an object/person and determine the chemical composition based on free-floating residue. Only super-hermetically sealed objects do not emit residues. Sniffers are good for detecting weapons and explosives, but poor for personnel identification. As such they are rarely used.

Heat sensors detect any changes in ambient room temperature and/or localized sources of heat/cold which may be human-shaped. Heat sensors are also part of the fire-detection system. Fuzzballs are small gadgets which emit waves of either heat or cold so as to conceal a person's thermal signature. They must be properly calibrated to the sensor's detection parameters or they will fail. Since heat-sensors must have high detection thresholds (or they would give false alarms on every warm day), they can be avoided by using Coolsuits set below the activation threshold.

Pressure sensors are either simple pads which activate an alarm when stepped upon/touched, or more sophisticated room sensors which detect changes in ambient pressure, indicating a break-in. The latter are often found in pressurized chambers such as bank vaults and laboratories. Pressure sensors are only used in areas which are rarely visited.

Cameras are capable of switching between spectrum frequencies such as infrared, ultraviolet and even gamma. Smart cameras (nicknamed smarteyes) are connected to citizen/criminal databanks which can identify a person from their posture/appearance/ facial features/voice or other characteristics. Regular cameras are the size of a marble and a normal building has hundreds of them installed in many places. Unlike today, there are no donut-munching rent-a-cops looking at the video output of every camera. Such a task would take too long, and security guards are notoriously unreliable at this boring function. Instead the computer system uses pseudo-AIs (or very rarely Great Minds) to detect intruders by identifying the shape of moving objects in the picture. Once the PSAI is reasonably certain of a problem, it alerts human supervisors. Countermeasures: Small holographic projectors can be used to take a snapshot of a location and project it by laser into the camera's viewer. Stealthsuits can be used to evade visual detection or to alter the shape/outline of the intruder, confusing the PSAI. Databank profiles can be altered so that the PSAI indentifies the intruders as friends, even if they're carrying an arsenal of weaponry. Tiny cameras can be shorted-out by a strong electromagnetic pulse.

Laser audio is a acoustic sensor system which can be used to hear tiny noises from across a hall by picking up the vibrations off any smooth surface (such as glass). Laser audio can be blanked with white noise generators or subverted with false noise recordings. Absolute silence requires Stealth + Dexterity [diff 8] rolls.

Motion sensors are usually combined with millimetre-radar to detect movement within certain specific parameters, and can thus be avoided by moving within their 'safe' movement rate. This can be as slow as 100 centimetres per second. Really paranoid security can calibrate the parameters to zero if they are sure no insects will ever enter the room. Motion sensors are prone to false alarms, so are used only in ultra-secure installations.

Sonic screens are harmless barriers which keep out insects and other vermin by inducing a painful planed signal to anything smaller than a cat. They kill parasites and bugs on contact and are often installed in office building doorways and windows. See 'sonic shower' for more information.