SI24592A - The interface for a secure connection of the burglary sensors and contactless card readers - Google Patents

Abstract

The interface for secure connection of burglar sensors and readers of contactless cards according to the invention enables the transmission of data through one communication channel, the interface address determining the priority of two interfaces, which simultaneously send a different message consisting of a larger number of bits by the same conductor, which is also monitored by the transmitter interface. The interface can transmit your message when the transmitter with a higher priority message finishes broadcasting. The message that an interface wants to send is composed by adding a unique transaction number to the message, which increases with each message, and the entire message is encrypted with the encryption key, which is determined for each system in advance, and the receiver decrypts the message and checks the transaction number.

Description

INTERFACE FOR SAFE CONNECTION OF ANTI-HARMONY SENSORS AND CONTACT CARD READERS

The subject of the invention is an interface for secure connection of anti-theft sensors and 5 contactless card readers, which provides an advanced and compatible network mode for secure connection of sensors and readers of newer and older generations of different manufacturers. The invention belongs to class H04I 7/00 of the international patent classification.

A technical problem that is successfully solved by the interface provided is the electronic circuitry, which provides a networking method for connecting sensors and readers of older generations that are not networked devices and eliminates the problem of compatibility with existing equipment or devices. the market's perseverance in the transition to a new generation of equipment. In addition, the solution according to the invention eliminates the barrier to a new generation of sensors and readers, that is, the absence of a general standard of connection or connection. network protocol that will allow the mixing of equipment from different manufacturers. Thus, individual manufacturers can only offer equipment that is closed by its own network protocol, which significantly reduces its market attractiveness.

The current method of connecting anti-theft sensors and readers with 20 contactless cards does not meet the ever-increasing security requirements as it allows for relatively easy intrusions or sabotage. On the other hand, the current way of connecting a large number of such devices to one port does not allow separation between devices, which is a serious deficiency in functionality and manageability. On the third hand, connecting these devices to individual ports is not an economical approach.

Thus, in patent document no. US 2010/0034375, which describes a transmission method at an interface to enhance the security of one-way communication protocols used in access control systems, such as e.g. VViegand protocol used enhancement in terms of equipping data with two-way packet communication and blind synchronization of pseudo-random number generators. The device is strictly intended for the protection of transmitted data when using the VViegand protocol, while io devices can be connected to the interface according to the present invention such as simple anti-theft sensors and the like. In addition, known converters convert the signal to a different form of signal, and the interface according to the invention uses the same physical mode of transmission, which means that we can use the same receiver as before.

is The interface for secure connection of anti-theft sensors and contactless card readers according to the invention eliminates the described limitations and provides an advanced connection method.

Anti-theft sensors are devices that can detect in many ways the presence of unauthorized persons on the premises. An anti-theft alarm system is a device that, with the help of connected anti-theft sensors, triggers an alarm in the presence of an unauthorized person in the room. The alarm status is communicated either via the connected light-sound indicator or via a communication channel to the security control center. The connection of the burglary sensors to the alarm panel, which is shown schematically in Figure 1, is currently made via a voltage-free contact. Such a contact either terminates or unlocks the contact to which the voltage is connected. In the normal state, the contact is closed and electrical current flows through the sensor and alarm contacts. When the sensor detects movement in the room or when a burglar sabotages the sensor, the contact is unlocked, thereby interrupting the electrical circuit. It also breaks the circuit when an attacker cuts through wires. Through the measurement of current, the alarm panel can monitor the condition of the burglary sensor. In this way, it is possible to connect a large number of anti-theft sensors to the chain at one terminal on the alarm panel. The disadvantage of this type of connection is that it is relatively easy to sabotage the sensors by short-circuiting the conductors near the alarm panel. In addition, if several sensors are connected to one terminal, the alarm panel cannot distinguish between the cause and the location of the alarm.

Contactless card readers use the electromagnetic field to read the data stored on the card and transmit it through the various interfaces to the controller for access control. Currently, the widespread two-wire connection method is called the “VViegand” interface and the protocol shown in Figure 2. At this interface, the identification code written in the binary system is transmitted by passing 0 digits of the binary system through one conductor and the other via 1. Next, the most important bit is passed. The voltage level 5V means that the line (conductor) is inactive and the voltage level OV is active. The data is transmitted along the falling voltage side of each transition between the inactive and active states. The controller can reconstruct the received code by monitoring the sequence of voltage level transitions on two lines.

Because data is transmitted in an unencrypted format for compatibility purposes, such data transmission carries a high security risk as the system cannot detect reader or transmission line sabotage. Because of this, only one reader can be connected to one pair of terminal blocks.

The interface for secure connection of anti-theft sensors and contactless card readers according to the invention enables data transmission through a single communication channel, where data is transmitted in binary format - digital format, with the interface address prioritizing when sending two interfaces simultaneously to send a different message consisting of multiple bits following the same conductor, with the is transmitter is designed to be able to monitor the current state even when transmitting a message, thus detecting when the transmitter with a higher priority message has overtaken it. It can transmit its message when a transmitter with a higher priority message ends broadcasting. The message that the interface wants to send is composed by adding a unique transaction number to the message, which is incremented with each message and encrypts the entire message with an encryption key that is assigned to each system in advance. The receiver decrypts the message and checks the transaction number. If the transaction number is inside the acceptance window, it forwards it to the system, otherwise rejects the message and reports possible sensor sabotage. To achieve a higher level of resistance to sabotage, the interfaces periodically report a sensor state after a predetermined period.

The invention will be explained in more detail on the basis of an embodiment and accompanying drawings, of which:

Figure 1 is a schematic illustration of a known method of connecting alarm sensors; Figure 2 is a schematic illustration of a known method of connecting contactless card readers:

3 is a schematic diagram of an interface circuit of the invention;

Figure 4 shows the connection of sensors and readers via the interface of the invention.

The interface for secure connection of anti-theft sensors and contactless card readers according to the invention is shown in Figure 3. The interface according to the invention consists of a power supply 6, a microcontroller 1, to which data lines 0 and 1 terminals are connected via level detection circuits to connect existing devices. The output of the microcontroller 1 is connected to the terminal of the encoded data line of the receiving device via the output amplifier 4. The encoder of the coded data line is connected to the input terminal of the microcontroller 1 via a level detection circuit 5.

A schematic illustration of the connection of multiple contactless card readers and anti-theft sensors via the interfaces according to the invention is shown in Figure 4.

In addition to the described interface for secure connection of burglary sensors and contactless card readers, an algorithm for processing protocols or protocols must be installed in order to upgrade the system to the receiving device. upgrade the receiving device software accordingly.

The mode of operation of the interface for secure connection of anti-theft sensors and contactless card readers according to the invention, where the interface according to the invention transmits data via one conductor - communication channel, is such that the data is transmitted in binary format - digital format, high voltage level is logically 0 (5V ) and a low voltage state of logic 1 (OV). Due to the specific design of the transmitter, which allows the detection of a higher priority message, the logic state 1 (OV voltage level) means the active state of the transmitter, and the logical state 0 means the inactive state of the transmitter (voltage level 5V). Data transfer can be described by the following steps:

determining that data is transmitted sequentially, the most important bit of the first message syllable is forwarded. A message can consist of several syllables. The transmission is started by placing the transmitter in the active state for a certain period, indicating the start of the transmission. The transmission of data is carried out by placing the transmitter in the active state (0 V) for a certain period of time, if the transmission line is logic state 1, otherwise the voltage level is 5V.

2o - specifying that logical state 1 is the preferred level, because if two interfaces want to send different messages simultaneously consisting of multiple bits along the same conductor, then that message having logical 1 prevails at the point where the messages first interact differentiate;

enabling monitoring of the status of the interface transmitter, which monitors the current state even when transmitting a message, so that it can detect when the transmitter of the interface with a higher priority message has overtaken it;

allowing the interface transmitter to transmit its message when the higher priority message interface transmitter terminates transmission; determining the interfaces that want to deliver their message to io by composing the message with a unique transaction number that is incremented with each message, and encrypting the entire message with an encryption key assigned to each system in advance. The length of a unique transaction number may vary depending on the choice of the encryption algorithm. It is usually 64 bits long. The encryption algorithm can be arbitrary, depending mainly on the capability of the microcontroller used in the receiving unit and the available software, allowing the receiver to decrypt the message and verify the transaction number. If the transaction number is inside the acceptance window, it forwards it to the system, otherwise rejects the message and reports possible sabotage of the sensor or contactless card reader;

allowing for higher levels of sabotage resistance to be reported periodically by the interfaces to a sensor or contactless card status after a predetermined period. If the receiver does not receive the appropriate message within the specified time, it reports sabotage.

The connection of contactless card readers and anti-theft sensors is upgraded with a more advanced network connection, which enables the control of individual sensor devices and significantly complicates intrusion or sabotage. The upgrade enables the use of existing readers and sensors through a simple and inexpensive network interface. The interface is so miniature and easy to connect that it allows mounting in virtually any situation, since it goes into the connection box, into the sensor device itself, or even to the connecting cable.

The interface for secure connection of anti-theft sensors and contactless card readers according to the invention provides advanced control over a large number of anti-theft sensors, contactless card readers and other similar devices. This allows the control of individual sensors or readers through one common connector, which significantly increases the functionality of the system. Furthermore, the potential for intrusion or sabotage is significantly reduced due to the use of advanced cryptographic security. The receiving device, alarm panel or access control controller now distinguishes between individual sensor readers and can not only detect but

2o also locates sabotage.

In this regard, it is crucial that the interface for secure connection of anti-theft sensors and contactless card readers according to the invention enables the use of standard readers and sensors, standard electrical conductors (lines) and connection to the same terminal terminals on the access control panel. This enables the upgrading of existing systems and the use of available equipment on the market.

Claims (3)

PATENT APPLICATION 1. Interface for secure connection of anti-theft sensors and contactless card readers according to the invention, 5, characterized in that data terminals 0 and 1 of terminals for connecting existing devices are connected to the inputs of the microcontroller (1) via level detection circuits (2,3), and the output of the microcontroller (1) is connected via an output amplifier (4) to the encoded data line terminal io of the receiving device and the coded data line terminal via a circuit (5) for level detection is connected to the input terminal of the microcontroller (1). 2. An interface according to claim 1, characterized in that it enables data transmission by means of a protocol comprising the following steps; specifying that data is transmitted sequentially, the most important bit of the first message syllable is forwarded; determining that logical state 1 represents the priority level, v 20 in the case where two interfaces wish to send a different message simultaneously consisting of a number of bits following the same conductor; enabling the monitoring of the status of the interface transmitter, which monitors the current state even when transmitting a message allowing the interface transmitter to transmit its message when the higher priority message interface transmitter terminates transmission; determining the interfaces that want to deliver their message to compose it by attaching a unique transaction number to the message; 5 - allowing for higher levels of sabotage resistance to be reported periodically by the interfaces after a predetermined period to the sensor or contactless card.