Most of the cards used in access control systems (ACS) - contain a fixed identification number, which is “stitched” at the factory and is available only for reading. With the use of smart cards, you can use both its serial number and data recorded in the non-volatile area. The organization of access control systems based on contactless smart cards allows you to increase the level of security of the system, virtually eliminating the possibility of card falsification. Rewritable cards exist with both open protocol and cryptography. Entering a new code into the crypto-protected area can be accomplished with the help of a special utility, and, further, the reader, which is also transferred to the operation mode with crypto-protected areas, will only apply to this area to read the code. In this area you can bring any combination of numbers and letters. To change the access codes to the protected area and enter them into the readers, a special master card is created (also with the help of the utility), after which you can use the computer to issue cards with new keys. When working with such cards and readers, you can change the access codes in the system even daily.