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It's in the cards.


HOW SECURE AGAINST COPYING, counterfeiting, and alteration are the encoded cards you issue employees? How secure do they need to be? How well will the card readers stand up to adverse weather or harsh interior environments? When selecting an access control system, these basic questions should be an important part of the process.

Many different access control encoding technologies are on the market today. They all perform the same basic function--to generate an encoded message for your system's computer to interpret and act on. Although the various technologies all produce the same results, they vary widely in their level of security for encoding and their readers' susceptibility to dirt, moisture, heat, cold, and vandalism. Therefore, it is important to select a system based on the level of encoding security you require and the environments the readers will face.

Eight basic card encoding technologies are on the access control market today. They are * Wiegand, * magnetic stripe, * proximity, * barium ferrite, * infrared, * bar code, * smart cards, and * Hollerith.

Of these card technologies, Wiegand, magnetic stripe, and proximity are estimated to share--about equally--85 to 90 percent of the market. Magnetic stripe has been in use the longest; Wiegand was introduced in 1979; and proximity has been gaining in use over the past five years.

Technologies based on magnetics include Wiegand, magnetic stripe, and barium ferrite. Optical technologies include infrared, bar code, and Hollerith. Proximity cards may use inductance, capacitance, or radio properties to store information. Smart cards use a microprocessor chip.

Manufacturers may use different coding formats. In general, however, the card code consists of a site code and a personal identification number (PIN). The site code identifies the location of the reader, a feature that allows access through a door in the event of a system malfunction. The PIN identifies the holder of a specific card.

Software in the access control system tells the computer or microprocessor what to do when a card is passed through a reader and a specific code is transmitted. At this point the reader will tell you whether the card is valid or invalid, whether an antipassback feature is present, what kind of tracking is incorporated, and whether the card is good for all doors or just selected doors. Whether your system covers only three or four doors and a few people or handles dozens of doors and hundreds of people, the whole process starts when a card and reader combination transmits a code to the system's computer.

The following is a review of the operating characteristics of the available technologies:

Wiegand. This technology--named after its inventor--uses a series of small diameter wires that, when subjected to a changing magnetic field, induce a discrete voltage output in a sensing coil. Two rows of wires are embedded in a coded strip laminated into the card. A read head is encapsulated in the reader. When the wires move past the read head, a series of pulses is generated and read as binary code. All Wiegand cards are factory encoded. The technology produces a card that is quite difficult to copy, counterfeit, or alter. Cards generally contain 26 or more wires, each representing a piece of information, allowing tens of millions of codes. Wiegand cards have a long useful life and are moderately priced.

Readers based on this technology are epoxy filled, making them immune to weather conditions. The readers operate over a wide temperature range, and neither cards nor readers are affected by external magnetic fields. Reader types include swipe (pass through) and insertion. An encoded key and reader are also offered.

Magnetic stripe. Magnetic stripe (mag stripe) cards have been in use many years. A strip of magnetic tape applied to one side of the card can store fairly large amounts of information, permitting large numbers of individual codes. Low-energy mag stripe cards are susceptible to alteration, copying, and abrasion. A high-coercivity (high-energy) mag stripe has been introduced that reduces the possibility of alteration or forgery. Mag stripe cards can be field encoded by the installer or the user. Some users find such a capability convenient, although it presents the possibility of card tampering. Cards are relatively inexpensive.

Mag stripe readers are usually of the swipe variety. Since they incorporate a read head similar to that in a VCR or tape recorder, they require periodic cleaning. Readers are also vulnerable to slot vandalism. In cold climates a heater may be required.

Barium ferrite. This older technology uses small bits of barium ferrite that are magnetized and located inside a plastic card. The polarity and the location of the barium ferrite spots determine the code. The security and resistance to duplication of these cards lies between the Wiegand and magnetic stripe cards. Perhaps the least expensive of the magnetic technologies, barium ferrite cards have a relatively short life cycle. They are used extensively in parking lots, where there is a high turnover rate and maximum security is not a consideration. Like Wiegand, they are factory encoded. Barium ferrite readers are of the insertion type only. Both cards and readers are subject to wear.

Proximity. Hands-free operation is the primary advantage of this type of card. Although several different circuit designs are used, all proximity cards permit the transmission of a code simply by bringing the card near the reader. Operating ranges are usually about 6 in. although greater distances are offered by varying antenna and circuit design.

Proximity cards tend to be quite thick, measuring up to .15 in., which is much thicker than the .030-in. standard set by the American Bankers Association. Since there is no direct contact between card and reader, wear is not a consideration. Proximity cards are factory encoded, making them quite secure and difficult to copy. They are more expensive than other technologies and have a relatively limited number of codes available.

Readers are generally shaped like flat plates from 5 to 8 in. on a side. They can be located behind a glass wall or other noninterfering material. Most, however, must be located away from metal door frames, studs, or beams by 6 to 12 in. If mounted on a metal wall, a standoff may be used. Proximity readers offer good resistance to moisture and temperature.

Infrared. Cards using infrared are offered by a few manufacturers but are not in widespread use. Cards are factory encoded. Encoding is accomplished by creating a shadow pattern within the card. The card is passed through a swipe or insertion reader that uses an infrared scanner. Infrared card pricing is moderate to expensive, and encoding is considered secure.

Infrared readers are optical and therefore vulnerable to contamination that can interfere with light transmission. Periodic cleaning may be needed.

Bar code. The use of bar codes for access control is limited. A bar code costs only a few cents and is easily produced in the field by the user. However, there is virtually no security, and the bar code strip can be damaged easily. At least one manufacturer offers a pouch to hide the bar code from view.

Hollerith. With this system, holes are punched in a plastic or paper card and read optically. One of the earliest technologies, the punched card is now seen most widely as an encoded key for hotels. The technology is not secure, but the cards are quite inexpensive.

Smart cards. Smart cards are not generally used for access control. These cards incorporate a small chip that interfaces with a reader by means of gold contacts. Quite expensive, they are used where large amounts of information must be stored on the card.

Laser. This technology is not widely used for access control. Several megabytes of information can be placed on the card, but the cards are expensive.

One other type of card should be mentioned--the temporary card. These are not encoded, and their visible message disappears after a period of time or when exposed to daylight. They are an inexpensive way to ensure visitors will not carry awy a permanent visitor's badge.

When cards are factory encoded on external number can be printed or hot stamped on the card. This can duplicate the internal code or can be a different number. In the latter case you should be supplied with a printed cross-reference list.

All manufacturers can supply their cards with your company identification, logo, and a message. Camera ready artwork is generally required.

Also, all manufacturers can supply card versions suitable for the addition of a photo carrying the holder's picture and pertinent printed information.

USE OF A COMMON CODE, USUALLY a site code, makes possible a low cost method of allowing holders into common areas. In this case, no personal identification number is included in the encoding. The site code can be used by a country club to allow members access to facilities they have paid for. For example, some members may be allowed use of the tennis courts. Cards given those members all will have the same site code. Others may have access only to the pool. Or, a health club may sell the use of its facilities on an individual basis. Members who have paid for racquetball privileges will have a card permitting access to the courts. Or, condominium owners can be given a card to access a gate-protected parking lot. Several manufacturers offer low cost electronics access systems based on the site code. Readers can be set up to accept only the code good for that location or can accept all site codes.

Today, upwards of 125 manufacturers or systems integrators offer access control systems. Offerings range from small, stand-alone units designed to protect a single door to systems capable of handling hundreds of doors and thousands of individual cardholders. The technologies vary from a simple admit or deny decision to complex systems capable of tracking each time the card is used and storing where it was used. Some systems incorporate other functions such as time and attendance.

Many systems integrators offer more than one card technology simply because each end user has different requirements and different budgetary restraints. Once a card and reader technology has been installed, it is not easy to change. Therefore, it is crucial to give close consideration to the technology your system will use.

Keep in mind you will be handling cards to large numbers of people, some of whom may not be entirely honest. Others will lose their cards. The cards should have a reasonably long life to protect your budget from high replacement costs. Consider also that not all of your card readers will enjoy life by the door of the chairman's office. Some will be outside, exposed to snow, sleet, rain, high humidity, extreme temperatures, and possibly vandals. Others may be operating in a factory, where a harsh environment can impose the need for frequent cleaning or shorten the reader's life.

When considering a system, discuss the available systems thoroughly with potential suppliers. Be careful to understand the capabilities of each technology in relation to the requirements and demands of your installation.

Richard L. Mourey is president of Tech/Comm, a marketing communications company in East Hartford, CT.
COPYRIGHT 1989 American Society for Industrial Security
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1989 Gale, Cengage Learning. All rights reserved.

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Title Annotation:security for encoded key cards
Author:Mourey, Richard L.
Publication:Security Management
Date:Jul 1, 1989
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