Remote communication for EMV Software

The term “remote-connected cards” defines smart cards that transmit data to a terminal at a distance of a few centimeters to about one meter. This characteristic of smart cards is of great interest for applications in which data should be exchanged between the card and the terminal without the mandatory requirement for the user to pick up the card and insert it into the terminal. Such applications are used for access control, identification of vehicles and luggage, such as electronic driver’s licenses, airline tickets, etc.

For many applications, there are different technical implementations, which makes standardization a difficult task, which is time-consuming to solve. The ISO working group was involved in this task in 1994. To date, two standards for smart cards have been mainly prepared-ISO/IEC 14443 and ISO / IEC 15633.

ISO/IEC 14443 covers a range of distances up to 10 cm, and the ISO/IEC 15633 – up to 1 meter. Two parts of the important ISO / IEC 10373 standard ” Identification Cards. Testing methods” and the international standard ISO/IEC 14443 ” Identification cards. Proximity contactless cards with integrated circuits”. Work on the ISO/IEC 14443 standard for proximity smart cards began in 1993. This type of card is designed for working distances up to 10 cm. This means that the card does not need to be placed in a certain place or inserted into the terminal.

The ISO/IEC 14443 standard consists of four parts:

  1. Part 1. Physical characteristics.
  2. Part 2. Radio frequency energy and signal interface.
  3. Part 3. Initialization and anti-collision.
  4. Part 4. Transmission protocol.

Part 1 of ISO / IEC 14443 “Physical Characteristics” describes:

  1. ID-1 card size compliance with ISO/IEC 7810 standard;
  2. Bending and other loads defined in ISO / IEC 10373;
  3. variables are the magnetic and electric fields;
  4. static magnetic and electric fields;
  5. Operating temperature (0°C to 50°C);
  6. the print quality on the surfaces of the card;
  7. possible limitations on the embossing of the card.

Part 2 of ISO / IEC 14443 “Radio Frequency Energy and Signal Interface” describes:

  1. the transfer of energy at a frequency of 13.56 MHz;
  2. Communication between the smart card and the reader with two different types of communication signal interfaces, types A and B.

Part 3 of the ISO / IEC 14443 standard “Initialization and anti-collision” describes:

  1. Polling of cards included in the reader field;
  2. Byte format, frames, and time charts; About the request and response commands to the request;
  3. anti-collision methods for selecting and communicating with one of several cards.

Part 4 of ISO / IEC 14443 “Transmission Protocol” describes:

  1. activation of the protocol for type A;
  2. half-duplex block transfer protocol;
  3. deactivating the card protocol.

International standard ISO/IEC 15693 ” Identification cards. Contactless cards of the vicinity type with integrated circuits ” specifies smart cards with an operating distance of up to 1 meter. Cards of this type are widely used in the protection of industrial facilities and the creation of various access systems. The original name of this standard” Hands-free card with integrated circuits ” reflects the fact that a card with a given working distance does not have to be held in your hand when used, it is enough to have it in your wallet or in your pants pocket.

The ISO/IEC 15693 standard consists of three parts:

  1. Part 1. Physical characteristics.
  2. Part 2. Air interface and initialization.
  3. Part 3. Anti-collision and transmission protocol.

Part 1 of the ISO / IEC 15693 standard “Physical characteristics” considers a number of physical characteristics, provides definitions for the behavior of a card exposed to static and variable electric and magnetic fields.

Part 2 of ISO / IEC 15693 “Air Interface and Initialization” describes the characteristics of power transfer and communication between the VCD reader and the VICC smart card, which must support several different modes:

  1. Power transmission: 13.56 MHz +7 kHz;
  2. inductive coupling;
  3. The magnetic field strength is about, 15-5 A / m.

Part 3 of ISO / IEC 15693 “Anti-collision and Transmission Protocol” describes:

  1. transmission protocol and commands;
  2. Other parameters required to initialize communication between the VICC card and the VCD reader;
  3. methods of selecting and communicating with one of several cards (anti-collision);
  4. data elements similar to the unique identifier and the application family identifier;
  5. memory organization;
  6. The behavior of VICC cards, described using state diagrams;
  7. set of commands (required, optional).

Standards for contactless smart cards

The task of preparing a standard for contactless cards was assigned to the ISO/IEC working group back in 1988. The task was to define a standard for contactless cards that would be largely compatible with other standards for identification cards. This would allow contactless smart cards to be used in existing systems that use other technologies.

The technical capabilities of contactless power and data transfer significantly depend on the required distance between the smart card and the reader during reading and writing. It is impossible to create a universal standard that would offer a single technical solution that meets the requirements of different applications. Therefore, the work was performed according to three different standards, designed for three different ranges of reading distance. Each of these standards, in turn, allowed for different technical solutions.

Currently, there are three different standards for contactless smart cards, developed in accordance with the classification of cards by reading distance. The standardization of smart cards began with the close communication cards (ISO/IEC 10536), because the microprocessors available at the time were characterized by relatively high power consumption, which made it impossible to transfer energy over a relatively long distance. Essential parts of this standard have been implemented and approved.

International standard ISO EC 10536 ” Identification cards: contactless cards with integrated circuits. Close-coupled cards ” describes contactless cards with inductive or capacitive coupling with an operating distance of a few millimeters. The user’s actions when using contactless cards with close connection (close-coupling) are defined as follows: insert the card into the slot of the reader or put it on the surface of the reader.

The ISO/IEC 10536 standard consists of four parts:

  1. Part 1. Physical characteristics.
  2. Part 2. The size and location of the communication areas.
  3. Part 3. Electronic signals and reset procedures.
  4. Part 4. Reset response and transfer protocols.

Data transfer from the card to the terminal. The first step in transmitting data from the card to the terminal is to generate an auxiliary carrier at 302.7 kHz using load modulation. The load change is at least 10%. Data modulation is achieved by switching the auxiliary carrier phase by 180°, which forms two phase values that can be interpreted as logical ones and zeros. The initial state after the occurrence of the magnetic field is defined as a logical unit. Each phase change of the auxiliary carrier represents a change in the logical state, which forms the NRZ encoding (not a return to zero).

Data transfer from the terminal to the card. To transmit data from the terminal to the card, four variable magnetic fields F1 – F4, which pass through the H1 – H4 coupling surfaces, are modulated in the PSK phase. This modulation causes all four fields to simultaneously change phase by 90°. For capacitive data transfer from the card to the terminal, one pair of surfaces with a capacitive connection is used (either E1 and E2, or EZ and E4, depending on the orientation of the card relative to the terminal). Another pair of surfaces with capacitive coupling can be used to transmit data in the opposite direction.

Because the smart card sends a response through one specific pair of capacitive-coupled surfaces, the terminal can recognize the relative orientation of the card. The maximum potential difference between a pair of surfaces with a capacitive coupling is limited to 10 V. Differential NRZ encoding is used for data transmission. The transmitter generates this code by changing the voltage between the surfaces E1 and E2 or E3 and E4.

It should be noted that smart cards with close communication, made in accordance with the ISO/IEC 10536 standard, currently no longer have much demand in the market due to the technical advantages of smart cards with remote inductive communication, specified in the ISO/IEC 14443 and 15693 standards.