They are also available in key fobs, buttons and other shapes. The reader emits a radio frequency that excites or energizes a little circuit in the credential; the credential then sends back its code to the reader for verification to the controller. If this sounds like an automotive transpon- der, it should since they use the same basic technology. Depending on the brand, read Figure 8. Smart cards are available in all kinds of configurations, from the mini- sim cards installed in cellphones to the cards installed in satellite or cable boxes. These cards are used for access control; the one on the top is a smaller chip used for transit applications. series of wires imbedded in it, is swiped through the reader to create a unique elec- trical output. It’s extremely difficult to copy but no longer used much, if at all. However, the format or language that was developed to communicate with the controller is still in use today and has become one of the standard languages. Proximity. Sometimes referred to as RFID or Radio Frequency ID, these are perhaps most popular for many higher security ac- cess control is the proximity card and reader (Figure 7). There are several reasons for this popularity. First, the short-range cards are relatively inexpensive (around $2 to $5 each); second, they are contactless, so they don’t require insertion or swiping through a reader. The reader can even be mounted on the inside of a pane of glass, and the card will still be read because the technology uses radio frequencies. Proximity comes in various styles based on the read range required. Short-range cards come in various shapes and sizes, but the most popular are the size of a credit card. 26 KEYNOTES SEPTEMBER 2014 range is around four to six inches. The long range will have a battery built into the card, because the reader can’t emit enough energy to excite the chip at great distances. Instead, the credential is actively sending out a signal that can be read at a distance of 20 to 30 feet. These credentials will be larger to accommodate the battery and a larger antenna. It used to be that prox- imity cards were not easily copied, but that has changed and they are now relatively easily copied. A wide variety of proximity card formats are available, from 26 bit to 140 bit. Each bit is a character position, but they are written in binary or computer language, meaning it’s either a 0 or a 1. The larger the number, the more different card combinations that are available — a bit like how the number of pin depths or chambers affects the number of key combinations. Smart. This card uses a computer chip that can be read and written to by the reader (Figure 8). It’s the same chip design used in SIM cards for cellphones and satellite boxes. They are available in both contact and con- tactless designs. The contactless design uses RFID similar to proximity cards, except the smart card design is read and write, where the standard proximity is read only. Contactless smart cards have been used for a wide variety of applications outside conventional access control, like the Mi- Fare, which is for transit fares and ATM cards, and for electronic wallets (reloadable cards). They’re also being used for medical records and many other applications, in- cluding computer access. Apps. The newest readers out don’t use a card at all; instead, they use a smartphone app. The technology is called NFC, or near- field communications. Currently the read range is similar to a prox card, at about four to six inches. Many applications already exist. As an example, some colleges are using this tech- nology because almost every student carries a cell phone — and the students tend to keep good tabs on their phones, whereas prox cards or student IDs are constantly getting lost. A big bonus here is that the cost of the credential is free to the college. Multiple formats. Many readers are multi-format or able to accept different card formats. As an example, a reader might ac- cept proximity and bar code or mag stripe, or a keypad with a built in proximity read- er. Most readers use some form of Wie- gand protocol communication; Wiegand is a language used to speak to the control. It requires three wires; ground, data 0 and data 1. With 0 data being communicated, the voltage will read about 5 volts; to trans- mit a “1,” the data 1 wire will drop voltage, and the data 0 will remain about 5 volts. To send a “0,” the data 0 wire will drop, and the data 1 will stay at 5 volts. Most manufactur- ers will accept Wiegand input but also offer their own proprietary format. Next issue: controllers. eg Perry, CML, CPS, is a tified master locksmith d certified professional e technician, working in phases of locksmithing. e has taught various lock- th topics for 10 years. He rently works in the public ctor as a locksmith. He s worked in the hardware ustry since 1975 in utional settings. He has ksmith magazines and is a r of the Year. Any opinions expressed by Greg in his articles are his alone and do not reflect any official government position. WWW.ALOA.ORG
