GB2593666A

GB2593666A - Pairing of wireless security devices

Info

Publication number: GB2593666A
Application number: GB2001788.5A
Authority: GB
Inventors: Derham Michael; Fortune Mark
Original assignee: Mighton Products Ltd
Current assignee: Mighton Products Ltd
Priority date: 2020-02-10
Filing date: 2020-02-10
Publication date: 2021-10-06
Also published as: GB202001788D0; WO2021161004A1

Abstract

A first device, such as a door lock 10, includes a first wireless radio communication module (26, Fig. 2) and a light source 28 for transmission of an encoded light signal. A second device, such as a wireless key fob 60 for the door lock, includes a light sensor (44, Fig. 2) for receiving the encoded light signal and a second wireless radio communication module (42, Fig. 2). Alignment means 70 are provided for cooperating with the first device and the second device to bring the light source and the light sensor into alignment. The alignment means preferably comprise an alignment tool. The encoded light signal transfers encryption data such as a temporary key. The first and second devices use the encryption data to establish a secure wireless radio connection, such as Bluetooth (RTM), between the first and second wireless radio communication modules. The encryption data may be used for Bluetooth pairing.

Description

PAIRING OF WIRELESS SECURITY DEVICES

FIELD

The present disclosure relates to a system of security devices, such as a door lock and associated wireless controller, and a method for pairing devices of the system.

BACKGROUND

Smart security systems that combine physical security with short-range or long-range data communication have become popular across a range of different applications. One type of smart security system includes a security lock that operates a mechanical or electromechanical locking mechanism of a door, gate, window or similar structure, and at least one wireless controller that can be used to control the operation of the lock remotely.

A smartphone can be used as a wireless controller in such a system. Usually, in such cases, the security lock connects with a local wireless area network (i.e. a Wi-Fi network) or, less commonly, a long-range wireless network (e.g. a GPRS or LTE network) to provide an internet connection to a secure server. The smartphone is configured to connect with the secure server so that instructions can be issued to the lock.

It may be desirable to provide an alternative or additional wireless controller in the form of a key fob device, which may be more convenient or easier to operate than a smartphone or other internet-connected device. In some examples, the key fob and the security lock may be configured to communicate with one another directly via a secure wireless radio connection, such as a Bluetooth connection.

As is known in the art, a Bluetooth connection can be used to exchange encrypted information in a relatively secure manner once the devices have been paired.

Broadly, pairing involves the exchange of encryption keys or other encryption data between the devices using one of several possible methods. A security vulnerability may arise if it is possible for a malicious third party to intercept or eavesdrop during -2 -the pairing process, thereby gaining knowledge of the encryption keys or allowing impersonation of the wireless controller (a so-called "man in the middle" or MITM attack).

Some known Bluetooth pairing methods, such as "LE legacy" connections in accordance with the Bluetooth 4.0 and 4.1 specifications, include the exchange of encryption data in the form of a temporary key between the devices over the Bluetooth radio connection, which is then used to create a short-term key to encrypt the connection. In a basic form, known as "Just Works", the temporary key is set to zero, and accordingly this method is highly vulnerable to MITM attacks. In other cases, the temporary key is a numeric passkey that is passed between the devices by a user. Although this approach offers slightly more resistance to MITM attacks, it is not generally suitable for use with devices that lack a display and keypad, which are not usually desirable features for a security lock system.

Other Bluetooth pairing methods, such as "LE secure" connections in accordance with the Bluetooth 4.2 and later specifications, involve the generation of a long-term key using Diffie-Hellman cryptography. In these cases, a temporary key is not exchanged during pairing. Instead, the exchanged encryption data takes the form of public keys, base values and modulus values, which can be used by each party to generate a common, secret, long-term key. When implemented in a "Just Works" method, this approach offers protection against eavesdropping, but can still be vulnerable to MITM attacks in which a third-party device impersonates the wireless controller during pairing.

To guard against MITM and other attacks, Bluetooth protocols allow for "out-ofband" pairing. In these cases, the encryption data is not exchanged over the Bluetooth radio connection, but instead is exchanged over an alternative wireless connection, such as near-field communication (NFC). This method may offer improved resistance to eavesdropping and MITM attacks, but this is dependent on the security of the out-of-band connection. For example, the resistance of NFC to eavesdropping and MITM attack is primarily based on the relatively short range of -3 -communication. However, in security-critical applications, this may not offer sufficient security for exchange of encryption data during pairing. Furthermore, the inclusion of NFC modules, with the associated design considerations, can increase the complexity, size and cost of the devices.

It is against this background that the present invention has been devised.

SUMMARY OF THE INVENTION

From a first aspect, the invention provides a system comprising a first device having a first wireless radio communication module and a light source for transmission of an encoded light signal, a second device having a light sensor for receiving the encoded light signal and a second wireless radio communication module, and alignment means for cooperation with the first device and/or the second device to bring the light source and the light sensor into alignment. The first device is configured to transmit encryption data to the second device by way of the encoded light signal, and the first and second devices are configured to use the encryption data to establish a secure wireless radio connection between the first and second wireless radio communication modules.

With this arrangement, encryption data can be exchanged during the pairing process of the first and second devices in a way that avoids any radio frequency broadcast of the data. In this way, the possibility of eavesdropping or MITM attack is substantially reduced or eliminated. The alignment means ensures that transmission of the encoded light signal can be reliably and securely performed.

The first and second wireless radio communication modules are preferably Bluetooth modules, and the encryption data is preferably used to determine an encryption key for exchange of data over a Bluetooh connection.

The alignment means may cooperate with the first device and/or the second device by engaging with the respective device. In an embodiment, the alignment means comprises an alignment tool arranged to engage with both the first device and the -4 -second device. The alignment tool may comprise a first side shaped to engage with the first device and a second side shaped to engage with the second device. The alignment tool may comprise an aperture providing a passage for transmission of the encoded light signal from the light source to the light sensor.

Preferably, for added security, the alignment tool comprises a shroud to conceal the encoded light signal during transmission of the encoded light signal. For example, when the alignment tool includes an aperture, the shroud may encircle or otherwise surround the aperture. When an alignment tool is not provided, the system may still include a shroud to conceal the encoded light signal during transmission of the encoded light signal, and in this case the shroud may be provided on the first and/or second device The alignment tool, when provided, may comprise at least one engagement feature for cooperation with the first device and at least one engagement feature for cooperation with the second device. Alternatively, when an alignment tool is not provided, the alignment means may comprise at least one engagement feature provided on one of the first or the second device for cooperation with the other of the first or the second device.

In either case, at least one of the engagement features may comprise a recess for receiving the respective first and/or second device. For example, the recess may be shaped to receive the whole or part of a body of the respective first or second device.

At least one of the engagement features may comprise a projection for cooperation with a corresponding recess in the respective first or second device. For example, the projection may comprise a pin for cooperation with a tool recess in a mounting fastener, such as a screw, of the respective first or second device. In another example, the projection comprises an annular or part-annular wall for cooperation with an annular recess of the respective first or second device. The annular recess may for example surround a push button of the first device and/or be associated with the light source. When the annular recess is provided in the first device, the -5 -annular recess may for example be associated with the light source.

Conveniently, the light source may comprise a status light of the first device. In this way, the cost and complexity of providing a dedicated light source for transmission of the encoded light signal can be avoided.

One of the first or second devices may comprise a security device and the other of the first or second devices may comprise a wireless controller configured to transmit commands to the security device over the secure wireless radio connection. For example, the security device may comprise a door lock, and the wireless controller may comprise a key fob.

The invention extends, in a second aspect, to a method for pairing a first device with a second device to allow subsequent secure wireless radio communication between the devices. The method comprises aligning a light source of the first device with a light sensor of the second device, and exchanging encryption data between the first and second devices by transmitting the encryption data from the first device as an encoded light signal using the light source, receiving the encoded light signal at the second device using the light sensor, and decoding the encoded light signal to provide the encryption data to the second device. The method further comprises using the encryption data in an encryption protocol for said secure wireless radio communication between the devices.

Using the encryption data in an encryption protocol for said secure wireless radio communication between the devices may comprise determining a temporary key or passkey from the encryption data, establishing a wireless radio connection between the first and second devices, and using the temporary key to exchange an encryption key between the first and second devices over the wireless radio connection. In other examples, the encryption data comprises a public key and associated data for use in a key exchange protocol, or an encryption key for use directly in the wireless radio communication. -6 -

Aligning the light source of the first device with the light sensor of the second device preferably comprises shrouding the light source to guard against leakage of light from the light source when transmitting the encryption data.

Aligning the light source of the first device with the light sensor of the second device may comprise disposing an alignment tool between the first and second devices. For example, the method may include engaging the alignment tool with the first device and engaging the second device with the alignment tool. The alignment tool may be engaged with the first device before the second device is engaged with the alignment tool. Alternatively, the second device may be engaged with the alignment tool before the alignment tool is engaged with the first device.

In an example, the first device comprises a security device, such as a lock for a door, window or similar structure, and the second device comprises a wireless controller for the security device. The second device may be operable to transmit an encrypted wireless radio instruction to the first device and the first device may be configured to receive and decrypt the encrypted wireless radio instruction and to perform an operation in accordance with said instruction.

Preferred and/or optional features of each aspect and embodiment of the invention may be used, alone or in appropriate combination, in the other aspects also.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which like reference signs are used for like features, and in which: Figure 1 shows a door lock system according to an embodiment of the invention; Figure 2 is a block diagram of the door lock system of Figure 1; Figure 3 is a perspective view of a pairing tool and a key fob of the door lock system -7 -of Figure 1; Figure 4 is another perspective view of a pairing tool and a key fob of the door lock system of Figure 1; Figure 5 is a front view of the key fob of the door lock system of Figure 1; Figure 6 is a rear view of the pairing tool of the door lock system of Figure 1; Figure 7 is a front view of the pairing tool of the door lock system of Figure 1; Figure 8 is a front view of part of a door lock of the door lock system of Figure 1; Figure 9 shows part of the door lock system of Figure 1 with the pairing tool engaged with the door lock; Figure 10 shows part of the door lock system of Figure 1 with the pairing tool engaged with the door lock and the key fob engaged with the pairing tool; Figure 11 shows part of the door lock system of Figure 1 with the key fob engaged with the pairing tool; Figure 12 shows a method of using the door lock system of Figure 1; and Figure 13 shows a method of transmitting encryption data in more detail.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to a system of wireless devices including first and second devices, one of which is configured as a wireless controller for the other in use, and a method of pairing the devices to facilitate secure communication therebetween. The invention is particularly suitable for a security system in which the first device is a security device in the form of a door lock and the second device -8 -is a wireless controller in the form of a key fob, and so the following description will refer primarily to that application.

Figure 1 shows a door lock system comprising a door lock 10, a key fob 40 and an alignment tool or pairing tool 70. Block diagrams of the door lock 10 and the key fob 12 are shown in Figure 2.

The door lock 10 is arranged to be mounted to a hinged door, on the inside of the door. The door lock 10 includes a lock cylinder (not shown) configured to operate a multi-point locking mechanism of the door, as is known in the art. Referring to Figure 2, the door lock 10 includes a motorised drive mechanism 12 and associated motor control module 14 that is operable to release and lock the locking mechanism of the door. A lock controller 16 provides suitable instruction inputs to the motor control module 14. A thumb-turn control 18, shown in Figure 1, is also provided to allow manual operation of the lock cylinder and a handle 20 is provided to operate a latchbolt of the locking mechanism. The door lock 10 also includes a push button 22 that operates a momentary switch 24 (see Figure 2), which can be operated by a user to issue commands to the lock controller 16, for example to cause unlocking or locking of the locking mechanism.

The key fob 40 acts as a wireless controller for the door lock 10. To this end, the key fob 40 and the door lock 10 each contain a Bluetooth module 26, 42, as shown in Figure 2, which together allow secure wireless radio communication between the key fob 40 and the door lock 10. To set up the radio communication link, it is necessary to "pair" the key fob 40 and the door lock 10 by an initial exchange of encryption data, such as a temporary encryption key or other information that allows an encryption key to be established, as will be described in more detail later.

To guard against "man-in-the-middle" attacks, where a third-party monitors the Bluetooth radio communication to eavesdrop on the initial exchange of encryption data, in the present invention the key fob 40 and the door lock 10 are configured to exchange the encryption data via an "out-of-band" communications link that does -9 -not use the Bluetooth radio link. Instead, the encryption data is exchanged using optical wireless communication. In this example, visible light communication is employed.

To this end, the door lock 10 includes a visible light source 28, which in this case comprises a ring of light-emitting diodes (LEDs) that encircle the push button 22 as shown in Figure 1. Referring again to Figure 2, the light source 28 is driven by an encoder 30 that receives encryption data to be transmitted to the key fob 40 from the (first) lock Bluetooth module 26, via the lock controller 16, and encodes the encryption data as a sequence of light flashes for transmission by the light source 28.

Referring additionally to Figure 3, the key fob 40 includes a light sensor 44 that is sensitive to light transmitted by the LEDs of the light source 28. In this example, the light sensor 44 is disposed on a top face 46 of the key fob adjacent to a push button 48. As shown in Figure 2, the light sensor 44 is connected to a decoder 50 that decodes the sequence of light flashes and outputs the decoded encryption data from the light sensor 44 to a fob controller 52 for use by the (second) fob Bluetooth module 42. The light sensor 44 is illustrated as a phototransistor, although any suitable light-sensitive component could be employed. The push button 48 operates a momentary switch 53, allowing a user to input commands to the fob controller 52.

Before exchanging the encryption data via optical light communication, it is desirable to bring the light sensor 44 of the fob into alignment with the light source 28 of the lock 10 so that the light sensor 44 can receive light of sufficient intensity from the light source 28 to minimise errors in data transmission. To this end, the pairing tool 70 provides a physical aid to assist a user in aligning the light source 28 with the light sensor 44.

Referring to Figures 3 to 5, the key fob 40 is generally pear-shaped in plan view, with a main body of the fob being formed by convex curved side edges 54 that each connect at a first end with a convex curved first end edge 56 and at a second end -10 -with a convex curved second end edge 58 that is longer than the first end edge 56. The side edges 54 and first and second end edges 56, 58 define a periphery around the top face 46, in which the push button 48 and light sensor 44 are disposed, and around a back face 60 that is generally parallel with the top face 46. The edges 54, 56, 58 are filleted where the top and back faces 46, 60 connect with the edges 54, 56, 58, so that the fob 40 has an ergonomic, comfortable shape. A tab 62 projects from the second end edge 58 and provides an aperture 64 for use with a key ring (not shown).

The pairing tool 70 in this example is an injection moulded, single-component part, and is shaped to engage both with the key fob 40 and with the front face of the door lock 10. The pairing tool 70 thereby includes engagement features for engaging the key fob 40 and the door lock 10. The pairing tool 70 can therefore be used to hold the key fob 40 in a predetermined position with respect to the door lock 10 in which the light sensor 44 is suitably aligned with the light source 28.

To this end, the front side 72 of the pairing tool, shown most clearly in Figures 4 and 7, comprises a recess 74 that has a complementary shape to the front side of the key fob 40, so that the key fob 40 can be inserted into the recess 74 with the top face 46 of the key fob 40 facing towards the pairing tool 70. The recess 74 is defined by a first end wall 76 that has a concave shape to correspond to the convex shape of the first end edge 56 of the key fob 40, by side walls 58 that generally follow the shape of the side edges 54 of the key fob 40, and by a second end wall 80 that has a concave shape to correspond to the convex shape of the second end edge 58 of the key fob 40. Each of the walls 76, 78, 80 connects with a back wall 82 of the recess 74 at a filleted region. Cut-outs 84 are provided in the side walls 78 of the recess 74 to allow the key fob 40 to be gripped on its side edges 54 for ease of insertion and removal from the tool 70. A cut-out 86 is also provided in the second end wall 80 of the recess 74 to accommodate the tab 62 of the key fob 40.

The back wall 82 of the recess is provided with an aperture 88 to allow light to pass through the pairing tool 70 The aperture 88 is disposed so that, when the key fob is placed in the recess 74, the aperture 88 is aligned with the light sensor 44.

On the rear side of the pairing tool 70, shown most clearly in Figures 3 and 6, a plurality of mouldings project rearwardly from the back wall 82 of the recess 74. A first moulding 90 forms a wall around an upper portion of the rear side of the pairing tool 70, and provides a rear edge 90a that defines a back plane of the pairing tool 70. The upper end of the pairing tool 70 has a concave recess 92, defined by a curved part 90b of the first moulding 90. A second moulding 94 forms a wall around a lower portion of the rear side of the pairing tool 70, and includes two rear edges 94a that also lie on the back plane.

In use, the rear edges 90a, 94a of the first and second mouldings 90. 94 are placed on flat areas of the front face 32 of the door lock 10, which is shown in more detail in Figure 8.

Returning to Figures 3 and 6, further mouldings on the rear side of the pairing tool 70 are arranged to engage with features on the front face 32 of the door lock 10. One further moulding comprises a pin 96 arranged to cooperate with the head of a mounting screw 34 of the door lock 10. The tip or rear end 96a of the pin 96 projects beyond the back plane of the pairing tool 70 so that, in use, the tip 96a of the pin 96 engages with the screwdriver slot in the head of the screw 34.

Another moulding 98 is arranged to engage with the ring of LEDs providing the light source 28 on the front face 32 of the door lock 10, which are slightly recessed with respect to the surrounding face. This moulding 98 therefore provides a part-annular wall 98b with a rear edge 98a that projects beyond the back plane of the pairing tool 70 so that, in use, the rear edge 98a of the part-annular wall 98b is received in the recess 36 formed by the ring of LEDs. The aperture 88 is disposed between the ends of the part-annular wall 98b, so that the part-annular wall 98b does not block the LEDs in the region of the aperture 88, allowing light to pass through the aperture 88 and to the light sensor 44 in use.

-12 -Between the ends of the part-annular wall 98b, the moulding 98 provides a shroud wall 98c that projects rearwardly from the periphery of the aperture 88 towards the light source 28 in use. The shroud wall 98c encircles the aperture 88 and serves both to reduce ambient light intrusion between the light source 28 and the light sensor 44 and to guard against leakage of light from the light source 28 that could otherwise be seen and recorded by an observer.

A pair of directional arrows 100 are provided on the front side of the pairing tool 70. These arrows 100 provide orientation means to allow the user quickly to identify the proper orientation of the pairing tool 70 with respect to the door lock 10. It will be appreciated that alternative or additional orientation means could be provided, for example in the form of pictographic or textual information.

An example of use of the pairing tool will now be described with reference to Figures 9 and 10.

In this example, the pairing tool 70 is first placed in position on the front face 32 of the door lock 10, as shown in Figure 9. The concave recess 92 at the upper end of the pairing tool 70 is shaped to fit around part of the generally cylindrical shaft 38 of the handle 20 of the door lock 10. The rear edges 90a, 94a of the pairing tool 70 that lie on the back plane of the tool 70 rest upon the front face 32 of the door lock 10. Although not visible in Figure 9, the part-annular wall 96b of the pairing tool 70 locates in the recess 36 associated with the ring of LEDs, and the pin 96 locates in the slot of the mounting screw 34. In these ways, the pairing tool 70 is arranged to be engaged with the lock 10 in only one position, with the aperture 88 aligned with an upper part of the ring of LEDs providing the light source 28. Misalignment of the pairing tool 70 with the lock 10 would be clearly identifiable by the user, since the pairing tool 70 would not sit properly on the face 32 of the door lock 10.

Once the pairing tool 70 is in place on the door lock 10, the key fob 40 can be inserted into the pairing tool 70, as shown in Figure 10. The light sensor 44 on the key fob 40 is therefore brought into alignment with the aperture 88 of the pairing tool 70, so that alignment of the light source 28 of the door lock 10 and the light sensor 44 of the key fob 40 is achieved and maintained. The exchange of encryption data via optical wireless communication can then proceed.

In another example, the key fob 40 is engaged with the pairing tool 70, as shown in Figure 11, before the pairing tool 70 is engaged with the door lock 10. Then the pairing tool 70 and key fob 40 together are positioned against the front face 32 of the door lock 10 (see Figure 10) to align the light source 28 and the light sensor 44.

It will be appreciated from Figure 10 that, in use, the pairing tool 70 is positioned so that it is very difficult or impossible for the encoded light signal transmitted by the light source 28 to be seen by an observer.

An example of the process of pairing the door lock 10 and the key fob 40 will now be described with reference to Figure 12.

First, in step 101, the pairing tool 70 is engaged with the lock 10 as described above with reference to Figure 9. Then, in step 102, the key fob 40 is engaged with the pairing tool 70 as described above with reference to Figure 10, to align the light sensor 44 of the fob 40 with the light source 28 of the lock 10. It will be appreciated that steps 101 and 102 could be reversed as previously described.

In step 103, the pairing process is initiated. This may be achieved, for example, by sending wireless commands to the lock 10 and the key fob 40 through a previously-established Wi-Fi connection to a smartphone, or by using the push buttons 22, 48 on each device to set each device into a pairing mode.

In step 104, encryption data is transmitted from the door lock 10 to the key fob 40, using the light source 28 and light sensor 44, as will be described in more detail below. In step 105, the key fob 40 is removed from the pairing tool 70, and in step 106, the pairing tool 70 is removed from the lock 10. Again, it will be appreciated that steps 105 and 106 could be reversed.

-14 -In step 107, wireless radio communication is initiated between the key fob 40 and the lock 10, using the Bluetooth modules 26, 42 in each device. The encryption data exchanged in step 104 is used in an encryption protocol for the wireless radio communication, as will be explained further below.

Figure 13 describes in more detail the process of transmitting encryption data in step 104 of Figure 12.

Once the pairing process has been initiated, in step 201, encryption data is generated by the lock controller 16, or alternatively the encryption data may be generated by the lock Bluetooth module 26 and then output to the lock controller 16. The encryption data may for example comprise an encryption key.

In step 202, the encryption data is encoded by the encoder 30 of the lock to generate an encoded light signal suitable for optical wireless communication. The encoded light signal may for example take the form of a sequence of flashes of the light source 28. In step 203, the light signal is transmitted from the light source 28 of the door lock 10. Preferably, the light signal is repeated several times, with suitable start and end indications.

In step 204, the light signal is received by the light sensor 44 of the key fob 40. Then, in step 205, the light signal is decoded by the decoder 50 of the key fob 40 to recreate the encryption data.

In step 206, the encryption data is used in an encryption protocol for subsequent wireless radio communication via the Bluetooth modules 26, 42 of the lock 10 and key fob 40.

For example, when the encryption data comprises an encryption key generated by the door lock 10, the result of the method of Figure 13 is that the encryption key is transmitted to the key fob 40. The encryption key is then known to both devices 10 and can be used to encrypt and decrypt data for radio transmission via the Bluetooth modules 26, 42. In such cases, the encryption key may be a temporary key (of relatively low complexity) that can be used to exchange securely a more complex short-term key via the Bluetooth radio connection, as is known from existing Bluetooth protocols. Another possibility is that the encryption key exchanged via optical wireless communication may be used as the key for encryption of all subsequent radio communications.

Instead of an encryption key, the encryption data may instead comprise information that can be used to generate a long-term encryption key. For example, the encryption data may comprise non-secret values for use in a key generation algorithm, such as the Diffle-Hellman key exchange protocol (as used in Bluetooth 4.2 and above). In a further example, the encryption data comprises authentication information, allowing the door lock to authenticate the key fob before or after pairing.

The term "encryption data" should therefore be interpreted broadly to encompass any preliminary data that is exchanged by optical wireless communication between the light source and the light sensor that is subsequently used to establish the secure wireless radio connection between the devices. In this connection, the encryption data need not itself be encrypted (although this option is possible).

In the above-described example, the ring of LEDs provides both the light source for optical wireless communication and a status display for the door lock. It will be appreciated, however, that any suitable light source could be provided. For example, a separate LED or other suitable light emitting device could be provided as the light source. The light source and light sensor need not operate in the visible spectrum. For example, light of infra-red or ultraviolet wavelengths could be used.

The light source could be provided on the key fob, with the light sensor provided on the door lock. In this case, the key fob can be considered as the first device of the system, and the door lock can be considered as the second device. It is also possible for each device to include both a light source and a light sensor, or a -16 -combined component, together with corresponding encoders and decoders to allow two-way optical wireless communication between the devices.

The devices may be implemented in any suitable way, with any suitable combination of hardware and software. It will be understood, for example, that two or more of the motor control module, lock controller, Bluetooth module and encoder of the door lock could be combined into a single module or processor. Similarly, two or more of the fob controller, Bluetooth module and decoder of the key fob could be combined into a single module or processor. The door lock and/or the key fob may include a microprocessor configured to implement one or more of the functions described herein.

In the above-described examples, the light sensor of the key fob and the light source of the door lock are aligned by engaging the key fob with the door lock via the pairing tool. To this end, the pairing tool may include any suitable engagement features for engaging the key fob on one side and the door lock on the other side. The engagement features may for example comprise projections, recesses, clips, pins, slots, tracks, channels, grips and so on. The engagement features may be arranged to cooperate with complementary features on the key fob or the door lock respectively, or may be arranged to cooperate with the body or case of the key fob or door lock, or with any other suitable component such as the handle of the lock or the tab of the key fob. Such engagement features may be provided alone or in any suitable combination.

The pairing tool may be configured to be releasably retained on the door lock when engaged, for example by clipping, frictional engagement, or any other suitable means. Similarly, the pairing tool may be configured to releasably retain the key fob when engaged. In this way, the assembly of the door lock, the pairing tool and the key fob need not be held together, so that a user's hands are free to operate a smartphone or other means to initiate the pairing process.

In another example (not illustrated), the pairing tool is omitted, and the key fob can -17 -be engaged directly with the door lock in such a way that the light source and light sensor are aligned after engagement. To this end, the key fob and/or the door lock may include alignment means for bringing the light source and the light sensor into alignment when the two devices are engaged with one another. For example, the 5 key fob may include mouldings or other elements that provide engagement features for cooperation with the recess associated with the ring of LEDs, the mounting screw head, the front face of the door lock, and/or other suitable features of the door lock. In these cases, the key fob may be releasably retained on the door lock after engagement. Shrouding of the light source may be achieved by providing a suitable 10 shroud on the key fob and/or the door lock.

While the above examples relate to a system comprising a door lock and a key fob, it will be understood that the concepts described herein are in no way limited to this application, and can be applied to substantially any system in which it is desirable to pair one device with another device, such as a wireless controller, with high security and resistance to eavesdropping and MITM attacks, but with minimal user input. Examples include smart window and other locks, smart light or electromechanical control switches, security safes, security alarm systems, and so on.

Further modifications and variations not explicitly described above can also be contemplated without departing from the scope of the invention as defined in the appended claims.

Claims

-18 -CLAIMS1. A system comprising: a first device having a first wireless radio communication module and a light source for transmission of an encoded light signal; a second device having a light sensor for receiving the encoded light signal and a second wireless radio communication module; and alignment means for cooperation with the first device and/or the second device to bring the light source and the light sensor into alignment; wherein the first device is configured to transmit encryption data to the second device by way of the encoded light signal, and wherein the first and second devices are configured to use the encryption data to establish a secure wireless radio connection between the first and second wireless radio communication modules.
A system according to Claim 1, wherein the alignment means comprises an alignment tool arranged to engage with both the first device and the second device.
A system according to Claim 2, wherein the alignment tool comprises a first side shaped to engage with the first device and a second side shaped to engage with the second device.
4. A system according to Claim 2 or Claim 3, wherein the alignment tool comprises an aperture providing a passage for transmission of the encoded light signal from the light source to the light sensor.
5. A system according to any of Claims 2 to 4, wherein the alignment tool comprises a shroud to conceal the encoded light signal during transmission of the encoded light signal.
-19 -A system according to any of Claims 2 to 5, wherein the alignment tool comprises at least one engagement feature for cooperation with the first device and at least one engagement feature for cooperation with the second device.
7. A system according to Claim 1, wherein the alignment means comprises at least one engagement feature provided on one of the first or the second device for cooperation with the other of the first or the second device.
8. A system according to Claim 6 or Claim 7, wherein at least one of the engagement features comprises a recess for receiving the respective first and/or second device.
9. A system according to any of Claims 6 to 8, wherein at least one of the engagement features comprises a projection for cooperation with a corresponding recess in the respective first or second device.
10. A system according to Claim 9, wherein the projection comprises a pin for cooperation with a tool recess in a mounting fastener of the respective first or second device.
11. A system according to Claim 7 or any of Claims 8 to 10 when dependent upon Claim 7, comprising a shroud to conceal the encoded light signal during transmission of the encoded light signal.
12. A system according to any preceding claim, wherein the light source comprises a status light of the first device.
13. A system according to any preceding claim, wherein one of the first or second devices comprises a security device and the other of the first or second devices comprises a wireless controller configured to transmit commands to the security device over the secure wireless radio connection.
14. A system according to Claim 13, wherein the security device comprises a door lock, and the wireless controller comprises a key fob.
15. A method for pairing a first device with a second device to allow subsequent secure wireless radio communication between the devices, the method comprising: aligning a light source of the first device with a light sensor of the second device; exchanging encryption data between the first and second devices by: transmitting the encryption data from the first device as an encoded light signal using the light source; receiving the encoded light signal at the second device using the light sensor; and decoding the encoded light signal to provide the encryption data to the second device; and using the encryption data in an encryption protocol for said secure wireless radio communication between the devices.
16. A method according to Claim 15, wherein using the encryption data in an encryption protocol for said secure wireless radio communication between the devices comprises: determining a temporary key from the encryption data; establishing a wireless radio connection between the first and second devices; and using the temporary key to exchange an encryption key between the first and second devices over the wireless radio connection.
17. A method according to Claim 15 or Claim 16, wherein aligning the light source of the first device with the light sensor of the second device comprises shrouding the light source to guard against leakage of light from the light source when transmitting the encryption data.
18. A 19. 20. 21. 22. 23.method according to any of Claims 15 to 17, wherein aligning the light source of the first device with the light sensor of the second device comprises disposing an alignment tool between the first and second devices.A method according to Claim 18, comprising engaging the alignment tool with the first device and engaging the second device with the alignment tool.A method according to Claim 19, wherein the alignment tool is engaged with the first device before the second device is engaged with the alignment tool.A method according to Claim 19, wherein the second device is engaged with the alignment tool before the alignment tool is engaged with the first device.A method according to any of Claims 15 to 21, wherein the first device comprises a security device and the second device comprises a wireless controller for the security device.A method according to any of Claims 15 to 22, wherein the second device is operable to transmit an encrypted wireless radio instruction to the first device and the first device is configured to receive and decrypt the encrypted wireless radio instruction and to perform an operation in accordance with said instruction.