Secure Key Generation in Wireless Networks

Abstract

According to an exemplary aspect of the present invention, a method is provided, comprising: transmitting timing information for security key adoption and information indicating a third wireless node to a second wireless node, transmitting a message for estimating a channel between the second wireless node and the third wireless node to the third wireless node, the message for estimating the channel comprising information indicating the second wireless node and channel measurement resource information associated with the second wireless node, obtaining a security key generated based on the channel estimation information, the channel estimation information being based on an estimate of the channel by the third wireless node, and applying the security key to encrypted data transmission between the first wireless node and the second wireless node.

Description

Technical Field

[0001] Various example embodiments relate generally to wireless networks and, more particularly, to improved security key generation in such networks, particularly for use in physical layer security arrangements. Background Art

[0002] Modern cryptography can be divided into two schools, including information theoretic and complexity-based security. Traditionally, only complexity-based security has been used, while information theoretic cryptography has been used with limited, if any, use. Information theoretic cryptography is based on information insufficiency, so it does not rely on computational difficulty. In other words, information theoretic cryptography can ensure secure communications even if unlimited computing power could be available. From a cryptanalytic point of view, information theoretic cryptography may be considered unbreakable, as there is usually not enough information for an adversary to break the encryption. Therefore, there are many applications where information theoretic cryptography is used.

[0003] Physical layer security PLS can be viewed as a form of information-theoretic cryptography, and PLS can be used to supplement and improve the security of communications in wireless networks. Using PLS, the inherent randomness of the wireless transmission channel, i.e., the uniqueness of the wireless channel between two physical locations in space and time, can be exploited to ensure secure communications.

[0004] Recently, there has been a need to design new and robust security protocols based on PLS, because application-level security may not be efficient and secure enough for emerging wireless communication systems. PLS can be used as an additional level of protection on top of or in place of traditional security schemes. Therefore, it would be desirable to adopt PLS to form a well-integrated security solution for wireless communication networks. Therefore, improvements are needed to achieve secure communications in wireless networks by adopting PLS. Summary of the invention

[0005] According to some aspects, the subject matter of the independent claims is provided. Some embodiments are defined in the dependent claims.

[0006] According to a first aspect, a device is provided, comprising components for: transmitting timing information for security key adoption and information indicating a third wireless node to a second wireless node, transmitting a message for estimating a channel between the second wireless node and the third wireless node to the third wireless node, the message for estimating the channel comprising information indicating the second wireless node and channel measurement resource information associated with the second wireless node, obtaining a security key generated based on the channel estimation information, the channel estimation information being based on an estimate of the channel by the third wireless node, and applying the security key to encrypted data transmission between the first wireless node and the second wireless node.

[0007] According to a second aspect of the present invention, a device is provided, comprising components for the following operations: receiving timing information for security key adoption and information indicating a third wireless node from a first wireless node, receiving channel measurement resource information associated with the third wireless node, receiving a trigger message for estimating a channel between a second wireless node and a third wireless node, generating channel estimation information based on an estimate of the channel in response to the received trigger message and based on the received channel measurement resource information, generating a security key based on the channel estimation information, and applying the security key to encrypted data transmission between the first wireless node and the second wireless node according to the received timing information for security key adoption.

[0008] According to a third aspect, a device is provided, comprising components for the following operations: receiving a message for estimating a channel between a second wireless node and a third wireless node from a first wireless node, the message for estimating the channel comprising information indicating the second wireless node and channel measurement resource information associated with the second wireless node, transmitting a reference signal to the second wireless node based on the received channel measurement resource information for directional or omnidirectional channel sensing to estimate the channel between the second wireless node and the third wireless node, generating channel estimation information based on the estimation of the channel, and transmitting the channel estimation information to the first wireless node for generating a security key for encrypting data between the first wireless node and the second wireless node or transmitting a security key generated by the first wireless device based on the channel estimation information to the first wireless node.

[0009] According to a fourth aspect, a first method for a first wireless node is provided, comprising: transmitting timing information for security key adoption and information indicating a third wireless node to a second wireless node, transmitting a message for estimating a channel between the second wireless node and the third wireless node to the third wireless node, the message for estimating the channel comprising information indicating the second wireless node and channel measurement resource information associated with the second wireless node, obtaining a security key generated based on the channel estimation information, the channel estimation information being based on an estimate of the channel by the third wireless node, and applying the security key to encrypted data transmission between the first wireless node and the second wireless node.

[0010] According to a fifth aspect, a second method for a second wireless node is provided, comprising: receiving timing information for security key adoption and information indicating a third wireless node from a first wireless node, receiving channel measurement resource information associated with the third wireless node, receiving a trigger message for estimating a channel between the second wireless node and the third wireless node, generating channel estimation information based on an estimate of the channel in response to the received trigger message and based on the received channel measurement resource information, generating a security key based on the channel estimation information, and applying the security key to encrypted data transmission between the first wireless node and the second wireless node according to the received timing information for security key adoption.

[0011] According to a sixth aspect, a second method for a third wireless node is provided, comprising: receiving a message for estimating a channel between a second wireless node and a third wireless node from a first wireless node, the message for estimating the channel comprising information indicating the second wireless node and channel measurement resource information associated with the second wireless node, transmitting a reference signal to the second wireless node based on the received channel measurement resource information for directional or omnidirectional channel sensing to estimate the channel between the second wireless node and the third wireless node, generating channel estimation information based on the estimation of the channel, and transmitting the channel estimation information to the first wireless node for generating a security key for encrypting data between the first wireless node and the second wireless node or transmitting a security key generated by the first wireless device based on the channel estimation information to the first wireless node.

[0012] According to some aspects, an apparatus comprises at least one processing core, at least one memory, the at least one memory comprising computer program code, the at least one memory and the computer program code being configured to, together with the at least one processing core, cause the apparatus to at least perform a method of any preceding aspect or an embodiment thereof.

[0013] According to some further aspects, a non-transitory computer readable medium is provided having stored thereon a set of computer readable instructions which, when executed by at least one processor, cause an apparatus to at least perform the method of any preceding aspect or an embodiment thereof.

[0014] According to further aspects, there is provided a computer program configured to perform the method of any preceding aspect or embodiments thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 illustrates example network scenarios according to at least some embodiments;

[0016] Figures 2 to 4 Methods according to at least some embodiments are shown;

[0017] Figure 5 shows examples of signaling according to at least some embodiments; and

[0018] Figure 6 Example apparatus is shown that can support at least some embodiments. DETAILED DESCRIPTION

[0019] Figure 1 An example network scenario is shown, including a wireless terminal 110 and a plurality of radio network nodes 120 , 130 , and 140 .

[0020] The wireless terminal 110 may include, for example, a user equipment UE, a smartphone, a cellular phone, a machine-to-machine M2M, a node, a machine type communication node, an Internet of Things IoT node, a car telemetry unit, a laptop computer, a tablet computer or virtually any type of suitable wireless user equipment or mobile station, i.e., a terminal.

[0021] The wireless terminal 110 may be attached to or connected to the radio network node 120 via an air interface for wireless communication. For example, the radio network node 120 may be considered a serving base station (BS) for the first wireless terminal 110. In general, the wireless terminal 110 and the radio network nodes 120-140 may be referred to as radio nodes. For example, the radio network node 120 may be referred to as a first radio node, the wireless terminal 110 may be referred to as a second radio node, and the radio network node 130 may be referred to as a third radio node.

[0022] The air interface between the wireless terminal 110 and the radio network node 120 may be configured according to the radio access technology RAT that both the first wireless terminal 110 and the radio network node 120 are configured to support. The air interface may include, for example, one or more beams between the first wireless terminal 110 and the radio network node 120. Examples of cellular RATs include long term evolution LTE, new radio NR, which may also be referred to as fifth generation 5G and MulteFire. On the other hand, examples of non-cellular RATs include wireless local area networks WLAN.

[0023] In the case of a cellular RAT, the radio network nodes 120-140 may be referred to as BSs and the wireless terminals may be referred to as UEs. For example, in the context of LTE, the radio nodes 120-140 may be referred to as eNBs, and in the context of NR, the radio nodes 120-140 may be referred to as gNBs. On the other hand, for example, in the context of WLAN, the radio nodes 120-140 may be referred to as access points. In any case, the embodiments of the present invention are not limited to any particular wireless technology. On the contrary, the embodiments of the present invention may be employed in any wireless communication system in which secure communications are desired.

[0024] The radio network node 120 may be connected to other network nodes 130, 140 via a wired or wireless connection 125. The radio network nodes 120-140 may be connected to the core network ( Figure 1 (not shown) connections, such as a next-generation core network, an evolved packet core (EPC), or other network management elements.

[0025] The radio access network and / or the core network may include various network functions. The network functions in this application may refer to operations and / or physical entities. A network function may be a specific network node or element, or a specific function or set of functions performed by one or more entities (such as a virtual network element). Examples of such network functions include radio access or resource control or management functions, mobility management or control functions, session management or control functions, intercommunication, data management or storage functions, authentication functions, or a combination of one or more of these functions. The core network may in turn be coupled to another network, via which a connection to another network may be obtained, for example via a global interconnected network.

[0026] A potential eavesdropper in the network, illustrated by terminal device 112 , may attempt to intercept and decode data transmissions 115 between wireless terminal 110 and wireless network node 120 .

[0027] In general, the development of wireless communications has brought new challenges to privacy and security. The security mechanisms currently used are usually based on classical cryptography. Classical cryptography may not be suitable for IoT communications. IoT devices usually have limited resources, such as processing power, communication capabilities and batteries, so the use of classical cryptography is usually not suitable for IoT devices. In contrast to classical cryptography, where security keys are stored, for example, in a subscriber identity module (SIM) card or generated using a hash function stored in a SIM card, physical layer security (PLS) can be provided by applying physical layer measurable parameters in the generation of confidentiality keys and protecting data using such PLS keys. Such physical, measurable variables can also be referred to as statistics, quantities and attributes. The physical, measurable variables can be estimated independently on both sides of the wireless terminal 110 and the wireless network node 120.

[0028] For example, if the channel H1 is used by the wireless terminal 110 and the radio network node 120, security can be improved assuming that it is only known at the wireless terminal 110 and the radio network node 120 (because this can be measured by sending reference signals). However, when data transmission may require a long period of time, channel prediction at the eavesdropper becomes more feasible with the use of a larger set of relevant information and by using a machine learning algorithm. For example, a demodulation reference signal (DMRS) may be sent for each data transmission instance, and channel estimation using DMRS may become a feasible option. With a larger set of available information and the predicted position of the wireless terminal 110, the channel estimate can be predicted and estimated more accurately. In addition, the use of channel estimation is more or less applicable to time division duplex (TDD) schemes, where the estimates of both parties should be more or less equal. The eavesdropper terminal 112 is therefore able to obtain more information not only through the network node 120 but also from the wireless terminal 110.

[0029] Improvements are now provided to address these challenges by providing a secret key establishment scheme that can employ measurements of a channel between the wireless terminal 110 and at least one further network node, such as the third network node 130 and / or the fourth network node 140. For example, a PLS encryption key can be generated based on measurements on the channel H2 based on the communication 117 between the nodes 110 and 130.

[0030] Figure 2 A method for arranging secure communications between wireless nodes is shown. The method may be applied by a first wireless node or device communicating with a second wireless node, such as a wireless network node 120 communicating with a wireless terminal 110 or UE.

[0031] The method includes transmitting (from a first wireless node) to a second wireless node timing information for controlling security key adoption and information indicative of a third wireless node 200. A message for estimating a channel between the second wireless node and the third wireless node is transmitted to the third wireless node 210. The message may include information indicative of the second wireless node and channel measurement resource information associated with the second wireless node.

[0032] Block 220 includes obtaining a security key generated based on channel estimation information based on an estimate of the channel by the third wireless node. In some embodiments, block 220 includes the further step of receiving channel estimation information based on an estimate of the channel by the third wireless node from the third wireless node and generating the security key based on the received channel estimation information. In an alternative embodiment, the third wireless node is configured to generate the security key based on the channel estimation information, and block 220 includes receiving the security key from the third wireless node.

[0033] The security key is applied 230 for data transmission between the first wireless node and the second wireless node. Thus, the security key is used to encrypt data and / or decrypt data between the first wireless node and the second wireless node, ie as an encryption key and / or a decryption key.

[0034] Figure 3 A method for arranging secure communication between wireless nodes is shown. The method may be applied by a second wireless node or device communicating with a first wireless node, such as a wireless terminal node 110 or UE communicating with a wireless network node, such as the first wireless network node 120.

[0035] The method includes receiving 300 timing information for security key adoption and information indicative of a third wireless node from a first wireless node. Block 310 includes receiving channel measurement resource information associated with the third wireless node.

[0036] A trigger message to estimate a channel between the second wireless node and the third wireless node is received 320. Based on the channel estimate in response to the received trigger message and based on the received channel measurement resource information, channel estimation information is generated 330. The channel estimate may be generated based on a measurement of a reference signal from the third wireless node.

[0037] A security key is generated based on the channel estimation information 340. The security key is applied 350 for encrypted data transmission between the first wireless node and the second wireless node according to the received timing information.

[0038] Figure 4 A method of supporting security key generation for a wireless node is shown. The method may be applied by a third wireless node, such as the third wireless network node 130, or an apparatus or controller included or contained in the third wireless node.

[0039] The method includes receiving 400 a message from a first wireless node to estimate a channel between a second wireless node and a third wireless node. The message may include information indicating the second wireless node and channel measurement resource information associated with the second wireless node. Based on the received channel measurement resource information, a reference signal is transmitted 410 to the second wireless node for directional or omnidirectional channel sensing to estimate the channel.

[0040] Based on the channel estimation in response to the received trigger message and based on the received channel measurement resource information, channel estimation information is generated 420. For example, the third wireless node may estimate the channel based on a reference signal (such as a sounding reference signal) or a response message from the second wireless node.

[0041] In some embodiments, the channel estimation information is transmitted 430 to the first wireless node for use in generating a security key for encrypting data between the first wireless node and the second wireless node. In some alternative embodiments, the third wireless node generates 440 a security key and transmits 450 the security key to the first wireless node.

[0042] It will be understood that various modifications may be performed and that additional stages / boxes may be present in the method(s) disclosed above. It is possible to perform at least some of the boxes in a different order. For example, in some embodiments, the information of boxes 300 and 310 is received from the first wireless node 120 in a single message, but in another embodiment, the channel measurement information is received from the third wireless node 130. As another example, the trigger message may be transmitted from the first wireless node to the second wireless node 110 and received from it along with the information in boxes 300 and 310. In yet another example variant, the trigger message of box 320 is received from the third wireless node, for example using or via a reference signal. Now referring to Figure 1 Some further example embodiments are illustrated with reference to example nodes of 3GPP 5G systems, but the disclosed features are not limited to such systems.

[0043] In some embodiments, the first wireless node 120 identifies a set of secondary wireless nodes that may be used to estimate a channel to the second node, the set including the third wireless node, prior to block 200. The first wireless node 120 may send information indicating the set of secondary wireless nodes to the second node, such as in block 200.

[0044] The first wireless node 120 may be configured to select the third wireless node 130 from the secondary wireless nodes in the set prior to block 200. The selection may be indicated for both the second wireless node and the third wireless node. Such a selection step may be entered before or after block 200. Thus, blocks 200 or 210 may be entered in response to the selection.

[0045] For example, the applied secondary wireless node can be identified or selected based on the location information of the secondary wireless node and the second wireless node. The first wireless node may include a prediction algorithm configured to predict and / or select (multiple) applicable secondary nodes. The prediction algorithm may apply a machine learning model. In one embodiment, the secondary wireless node is selected based on a radio channel measurement report from the second wireless node. For example, initial or periodic feedback from the UE regarding the received signal quality, such as based on synchronization signal block (SSB) reception. In another example embodiment, the first wireless node configures UL reference signal transmission (or scanning) to different directions and coordinates with other wireless nodes to learn the secondary wireless node that is best in terms of received channel quality.

[0046] The applied secondary wireless node may be selected within the set based on random selection, such that an eavesdropper cannot predict it. In some other example embodiments, the secondary wireless node may be selected within the set based on channel quality and / or directional information of the corresponding secondary wireless node. Thus, the first wireless node may select a secondary wireless node that communicates from a different direction (substantially) than the first wireless node. The applied secondary wireless node may be changed, for example periodically and / or selected each time a security key needs to be generated.

[0047] In another embodiment, multiple secondary wireless nodes are applied to generate or update a security key between the first wireless node 120 and the second wireless node 110. Therefore, in addition to transmitting the first channel measurement configuration associated with the third wireless node 130 to the second wireless node and to the third wireless node, the first wireless node may transmit the second channel measurement configuration associated with the fourth wireless node to the second wireless node and the fourth wireless node in the set of secondary wireless nodes. The first wireless node may transmit an indication to perform channel estimation for the second wireless node to at least some of the secondary wireless nodes in the set. The first wireless node may transmit a specific indication to the second wireless node to perform channel estimation with multiple secondary wireless nodes. Channel estimation information may be received from multiple secondary wireless nodes, and a security key may be generated based on at least some of the channel estimation information received from the set of secondary wireless nodes.

[0048] In some embodiments, the first wireless node 120 transmits channel measurement resource information associated with the third wireless node 130 to the second wireless node 110. This may be performed with other information in block 300 or configured separately from block 300. In another embodiment, the third wireless node transmits the channel measurement resource information to the second wireless node after block 210.

[0049] The timing information used for security key adoption may be a configurable predefined parameter. The timing information may be dynamically determined based on one or more of the following information: a return delay, a propagation delay, and a channel state information calculation delay associated with performing channel estimation between the second wireless node and the third wireless node. This can ensure that the second wireless node does not apply the security key too early. However, it will be understood that various other embodiments are also applicable to setting the encryption timing information to the second wireless node 110. It should also be noted that the security key can be generated (and then used directly) based on the timing information.

[0050] Security keys may be generated 340, 440 based on the channel estimation information to encrypt physical layer messages according to the PLS method in blocks 230, 350. The security keys may be provided to a PLS encryption module included in the node 110, 120 and configured to encrypt and / or decrypt PLS encrypted messages.

[0051] It should be understood that the present feature can be applied in conjunction with a variety of different PLS methods and PLS security keys. In some example embodiments, the security key is a scrambling sequence, where the sequence is generated by a set of predefined steps, but at least some channel estimation information is used as an input parameter to the steps to make it unique. In one embodiment, the scrambling sequence generation can be initiated by a component or parameter of an estimated channel between the second wireless node and the third wireless node. For example, the first wireless node 120 and the second wireless node 110 can be configured to obtain a long-term quantity in the measurement information in the channel estimation information and use the quantity as a seed for a hash function to generate a security key.

[0052] Reference is made to a diagram showing an example of signaling according to some embodiments. Figure 5 , its reference Figure 1 As previously described, for example, the second wireless node 110 may be a terminal node, such as a UE, and the (first, third and fourth) wireless nodes 120-140 may be network nodes, such as base stations or gNBs.

[0053] The first wireless node 120 transmits a first channel measurement configuration (associated with the third wireless node) to the third wireless node 130 via message 500 and to the second wireless node 110 via message 504. The first wireless node 120 also transmits a second measurement configuration (associated with the fourth wireless node) to the second wireless node 110 via message 504 and to the fourth wireless node 140 via message 502. It should be noted that the configuration may alternatively be sent to the second wireless node 110 in a separate message.

[0054] In some embodiments, channel estimation may be performed using a channel state information-reference signal (CSI-RS) from the third wireless node 130 to the second wireless node 110. The CSI-RS may be used by the second wireless node 110 to estimate the channel. Thus, the measurement configuration of the messages 500, 502, 504 may include CSI-RS resource information.

[0055] In some embodiments, channel estimation may be performed at the secondary wireless node(s) 130, 140 based on a sounding reference signal (SRS) transmitted by the second wireless node 110. Thus, the measurement configuration of the messages 500, 502, 504 may include SRS resource information.

[0056] The first wireless node 120 may be configured to transmit a specific trigger message to the second wireless node 110 and one or more secondary wireless nodes (ie, at least a third wireless node) for estimating a channel between the second wireless node and the third wireless node. Figure 5In the example of , the first wireless node 120 selects the third wireless node 130 to perform channel estimation information for security key generation purposes. Therefore, the first trigger message 506 is transmitted to the third wireless node 130 and the second trigger message 510 is transmitted to the second wireless node 110 to control the estimation of the channel between the nodes 110 and 130.

[0057] In one embodiment, after transmission of the first trigger message 506 to the third wireless node, the first wireless node 120 activates a timer and applies a waiting period 508 before transmitting the second trigger message 510. As long as the second wireless node 110 does not receive the first trigger message from the first wireless node 120, it does not have to measure the channel for security key generation purposes or transmit a reference signal to the third wireless node 130.

[0058] In some embodiments, the first wireless node 120 transmits channel estimation timing information to the secondary node (such as the third wireless node 130) for controlling the timing of the reference signal from the third wireless node to the second wireless node for channel estimation. For example, the channel estimation timing information may be transmitted in the first trigger message 506. Based on the channel estimation timing information, the third wireless node 130 initiates channel measurement and may transmit a reference signal 514, such as a CSI-RS, for the second wireless node 110 to estimate the channel based on the received CSI-RS resource information.

[0059] This enables proper timing of channel measurements by the nodes 110 and 130. In another embodiment, instead of or in addition to the waiting period 508, channel estimation timing information is included in the second trigger message 510, on the basis of which the second wireless node 110 initiates channel measurements, e.g., is adapted to receive a CSI-RS message based on the received channel measurement resource information.

[0060] The second wireless node 110 generates channel measurement information based on the received reference signal 514 and generates 518 a security key based on the channel measurement information. The second wireless node 110 also transmits a reference signal 516, such as an SRS, to the third wireless node according to the received first channel measurement configuration (504).

[0061] The third wireless node 130 receives the reference signal 516 and generates 520 channel measurement information based on the received reference signal 516. The third wireless node 130 transmits the channel measurement information 522 to the first wireless node 110, and the first wireless node 110 generates 524 a security key based on the received channel measurement information 522. Messages 526, 528 may then be transmitted between the wireless nodes 110, 120 by applying the generated security key.

[0062] The message 504 to the second wireless node 110 may include timing information for security key adoption. In some embodiments, the timing information for security key adoption indicates a time interval 512. The second wireless node may be configured to trigger a timer in response to the trigger message 510 and start using the security key only after the time interval 512 has elapsed (in block 350).

[0063] For example, the above features can be applied in a network operating according to the 3GPP standard, such as in a 5G / NR network. In the case of 5G NR, the currently disclosed features can be implemented by extending the CSI framework defined in NR. CSI-RS can be used for different cells to transmit CSI-RS, and the UE can measure them by associating to the SSB of the cell.

[0064] At least some of the above messages may be 5G RRC messages. The information shown above to and from the first wireless node 120 may be added as new (multiple) information elements to the existing (multiple) control messages and / or may specify new message types. (Multiple) 3GPP 5GRRC messages may be applied between the gNB and the UE. For example, message 504 may include a CSI-ResourceConfig element and an SRS-ResourceSet element for resource information, and the second trigger message 510 may include a DCI field CSI request and a DCI field SRS request, which may be modified for this purpose and include additional information or (multiple) elements. (Multiple) 3GPP 5G Xn interface messages may be applied between gNBs.

[0065] Also like Figure 5As another option, the features shown above can be applied in conjunction with a multiple transmission reception point (TRP) system, which includes a primary TRP (which can operate as the first wireless node 120 shown above) and a set of secondary TRPs (which can operate as the third wireless node 130 and the fourth wireless node 140 shown above). In such a scenario, the CSI-RS and SRS configurations can also be configured to the UE via RRC signaling, and the corresponding configurations are indicated to the secondary TRPs. The primary TRP can coordinate with the secondary TRP when to transmit / receive CSI-RS and SRS. The primary TRP can also control the timing information for the adoption of security keys for the UE so that it has enough time to measure CSI, transmit SRS, and generate PLS keys. For example, secondary TRP1 can transmit CSI-RS, measure SRS, and estimate CSI based on the measured SRS. TRP1 then feeds back the estimated CSI to the primary TRP so that the primary TRP can generate a PLS key. Once the PLS key is generated at both the primary TRP and the UE, the key will be applied after the timing information for the adoption of security keys. This process can be further continued for another secondary TRP.

[0066] The present embodiments thus contribute to solutions for physical layer encryption.More specifically, at least some embodiments provide a solution that can further increase the level of security by making it more difficult for an eavesdropper to obtain information used to generate security keys.

[0067] By applying the features shown above, radio and power resources can be used more optimally because the secondary wireless node or TRP can transmit reference signals only when needed (at the appropriate time) to generate security keys, and the UE does not measure them or transmit SRS unnecessarily. Since the data transmission does not utilize the secondary wireless node or TRP bearer, the estimated channel generates PLS keys more securely and provides security for data transmission between the first or primary wireless node and the second wireless node or UE.

[0068] An electronic device including an electronic circuit system may be a device for implementing at least some embodiments of the present invention. The device may be or may be included in a computer, a laptop, a tablet, a cellular phone, a machine-to-machine (M2M) device (e.g., an IoT sensor device), a base station, an access point or a network node device, or any other device provided with radio communication capabilities. In another embodiment, the device for performing the above functions is included in such a device, for example, the device may include a circuit system, such as a chip, a chipset, a microcontroller, or a combination of these circuit systems in any of the above devices.

[0069] Figure 6 An example apparatus capable of supporting at least some embodiments of the present invention is shown. Shown is a device 600, which may include, for example Figure 1 The first wireless terminal node 110, the wireless network node 120 or 130, or the device 600 may be configured to control the functions thereof, possibly when installed therein. The apparatus may be configured to perform Figure 2 , Figure 3 or Figure 4 or methods of embodiments thereof.

[0070] Included in the device 600 is a processor 610, which may include, for example, a single-core or multi-core processor, wherein a single-core processor includes one processing core and a multi-core processor includes more than one processing core. The processor 610 may generally include a control device. The processor 610 may include more than one processor. The processor 610 may include at least one application-specific integrated circuit ASIC. The processor 610 may include at least one field-programmable gate array FPGA. The processor 610 may be a component for performing method steps in the device 600. The processor 610 may be configured at least in part by computer instructions to perform actions.

[0071] The processor may include circuitry, or be constituted of one or more circuitry, configured to perform the stages of the method according to the embodiments described herein. As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) a hardware circuit implementation only (such as an implementation in analog and / or digital circuitry only), and (b) a combination of hardware circuitry and software, such as, as applicable: (i) a combination of (multiple) analog and / or digital hardware circuits with software / firmware, and (ii) any portion of (multiple) hardware processors with software (including (multiple) digital signal processors), software and (multiple) memories, which work together to enable the device (such as a mobile phone or server) to perform various functions) and (c) (multiple) hardware circuits and / or (multiple) processors, such as (multiple) microprocessors or portions of (multiple) microprocessors, which require software (e.g., firmware) to operate, but the software may not be present when the operation does not require the software.

[0072] This definition of circuitry applies to all uses of the term in this application, including in any claims. As another example, as used in this application, the term circuitry also covers an implementation of only a hardware circuit or a processor (or multiple processors) or a portion of a hardware circuit or a processor and its (or their) accompanying software and / or firmware. For example, the term circuitry also covers a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, cellular base station, or other computing or base station, if applicable to the particular claim element.

[0073] Device 600 may include memory 620. Memory 620 may include random access memory and / or permanent memory. Memory 620 may include at least one RAM chip. For example, memory 620 may include solid-state, magnetic, optical and / or holographic memory. Memory 620 may be at least partially accessible by processor 610. Memory 620 may be at least partially included in processor 610. Memory 620 may be a component for storing information. Memory 620 may include computer instructions, and processor 610 is configured to execute the computer instructions. When computer instructions configured to cause processor 610 to perform certain actions are stored in memory 620, and device 600 as a whole is configured to run under the guidance of processor 610 using computer instructions from memory 620, processor 610 and / or at least one of its processing cores may be considered to be configured to perform the certain actions. Memory 620 may be at least partially included in processor 610. Memory 620 may be at least partially external to device 600 but accessible to device 600. The memory may store parameters that affect the operation of the device, such as those described above in conjunction with Figures 2 to 4 Some or all of the functionality shown.

[0074] The device 600 may include a transmitter 630. The device 600 may include a receiver 640. The transmitter 630 and the receiver 640 may be configured to transmit and receive information according to at least one cellular or non-cellular standard, respectively. The transmitter 630 may include more than one transmitter. The receiver 640 may include more than one receiver. For example, the transmitter 630 and / or the receiver 640 may be configured to operate according to the Global System for Mobile Communications GSM, Wideband Code Division Multiple Access WCDMA, 5G / NR, Long Term Evolution LTE, IS-95, Wireless Local Area Network WLAN and / or Ethernet standards.

[0075] The device 600 may include a near field communication NFC transceiver 650. The NFC transceiver 650 may support at least one NFC technology, such as NFC, Bluetooth, Wibree, or similar technology.

[0076] The device 600 may include a user interface UI 660. The UI 660 may include at least one of a display, a keyboard, a touch screen, a vibrator arranged to signal a user by vibrating the device 600, a speaker, and a microphone. The user may be able to operate the device 600 via the UI 660, such as accepting an incoming call, making a phone call or a video call, browsing the Internet, managing digital files stored in the memory 620 or on a cloud accessible via the transmitter 630 and the receiver 640 or via the NFC transceiver 650, and / or configuring the operation of the device.

[0077] The device 600 may include or be arranged to accept a user identification module 670. The user identification module 670 may include, for example, a subscriber identification module SIM card installable in the device 600. The user identification module 670 may include information identifying a subscription of a user of the device 600. The user identification module 670 may include cryptographic information that may be used to verify the identity of the user of the device 600 and / or facilitate encryption of communication information for communications conducted via the device 600 and billing of the user of the device 600.

[0078] The processor 610 may be equipped with a transmitter arranged to output information from the processor 610 to other devices included in the device 600 via electrical conductors inside the device 600. Such a transmitter may include a serial bus transmitter arranged to output information to the memory 620 for storage therein, for example, via at least one electrical lead. As an alternative to the serial bus, the transmitter may include a parallel bus transmitter. Similarly, the processor 610 may include a receiver arranged to receive information in the processor 610 from other devices included in the device 600 via electrical leads inside the device 600. Such a receiver may include a serial bus receiver arranged to receive information from the receiver 640, for example, via at least one electrical lead for processing in the processor 610. As an alternative to the serial bus, the receiver may include a parallel bus receiver.

[0079] The device 600 may include Figure 6 Other devices not shown in the figure. For example, where the device 600 includes a smartphone, it may include at least one digital camera. Some devices 600 may include a rear camera and a front camera, wherein the rear camera may be intended for digital photography and the front camera is used for video calling. The device 600 may include a fingerprint sensor arranged to at least partially authenticate a user of the device 600. In some embodiments, the device 600 lacks at least one of the above devices. For example, some devices 600 may lack an NFC transceiver 650 and / or a user identification module 670.

[0080] The processor 610, the memory 620, the transmitter 630, the receiver 640, the NFC transceiver 650, the UI 660 and / or the user identification module 670 can be interconnected in a variety of different ways through electrical leads inside the device 600. For example, each of the above devices can be separately connected to a main bus inside the device 600 to allow the devices to exchange information. However, as will be appreciated by those skilled in the art, this is only an example, and depending on the embodiment, various ways of interconnecting at least two of the above devices can be selected without departing from the scope of the present invention.

[0081] It should be understood that the disclosed embodiments of the present invention are not limited to the specific structures, process steps or materials disclosed herein, but are extended to equivalents thereof that will be recognized by those of ordinary skill in the relevant art. It should also be understood that the terms used herein are only used for the purpose of describing specific embodiments and are not intended to be limiting.

[0082] References to an embodiment or an embodiment throughout the specification mean that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present invention. Thus, the phrases "in an embodiment" or "in an embodiment" appearing in various places throughout the specification do not necessarily all refer to the same embodiment. Where a value is referred to using terms such as, for example, about, or substantially, the exact value is also disclosed.

[0083] As used herein, multiple items, structural elements, constituent elements and / or materials may be presented in a public list for convenience. However, these lists should be interpreted as if each member of the list is individually identified as a separate and unique member. Therefore, in the absence of contrary instructions, any single member in such a list should not be interpreted as the de facto equivalent of any other member in the same list based solely on its presentation in a public group. In addition, various embodiments and examples of the present invention may be mentioned in this article together with the alternatives of its various components. It should be understood that these embodiments, examples and alternatives should not be interpreted as de facto equivalents to each other, but should be regarded as separate and autonomous representations of the present invention.

[0084] In an exemplary embodiment, an apparatus (such as, for example, the first wireless terminal 110 or the radio network nodes 120, 130) may include means for performing the above-described embodiments and any combination thereof.

[0085] In an exemplary embodiment, a computer program may be configured to cause a method according to the above embodiments and any combination thereof. In an exemplary embodiment, a computer program product embodied on a non-transitory computer readable medium may be configured to control a processor to perform a process including the above embodiments and any combination thereof.

[0086] In an example embodiment, an apparatus (such as, for example, the first wireless terminal 110 or the wireless network node 120, 130) may include at least one processor and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to at least perform the above-mentioned embodiments and any combination thereof.

[0087] In addition, the described features, structures or characteristics may be combined in any suitable manner in one or more embodiments. In the foregoing description, many specific details, such as examples of length, width, shape, etc., are provided to provide a thorough understanding of embodiments of the present invention. However, those skilled in the relevant art will recognize that the present invention may be practiced without one or more of the specific details, or using other methods, components, materials, etc. In other cases, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the present invention.

[0088] Although the foregoing examples illustrate the principles of the present invention in one or more specific applications, it is obvious to those skilled in the art that many modifications may be made in the details of form, use and implementation without exercising creative ability and without departing from the principles and concepts of the present invention. Therefore, the present invention is not intended to be limited except by the claims set forth below.

[0089] The verbs "comprise" and "include" are used in this document as open limitations, which neither exclude nor require the existence of unrecited features. Unless explicitly stated otherwise, the features recited in the dependent claims may be freely combined with each other. Furthermore, it should be understood that the use of "a" or "an" (i.e. the singular form) in this document does not exclude a plurality.

Claims

1. An apparatus for a first wireless node, comprising: - means for transmitting to the second wireless node timing information for adopting the security key and information indicating the third wireless node, - means for transmitting, to the third wireless node, a message for estimating a channel between the second wireless node and the third wireless node, the message for estimating the channel comprising information indicating the second wireless node and channel measurement resource information associated with the second wireless node, - means for obtaining a security key generated based on channel estimation information, said channel estimation information being based on an estimation of said channel by said third wireless node, and - means for applying said security key to encrypted data transmissions between said first wireless node and said second wireless node.

2. The device according to claim 1, wherein the device comprises - means for receiving, from said third wireless node, channel estimation information based on an estimation of said channel by said third wireless node, and - means for generating said security key based on said received channel estimation information.

3. The apparatus of claim 1, wherein the apparatus comprises means for receiving the security key from the third wireless node.

4. An apparatus according to any preceding claim, wherein the apparatus comprises means for repeatedly identifying a set of secondary wireless nodes that can be used to estimate a channel to the second wireless node, the set including the third wireless node.

5. The device according to claim 4, wherein the device comprises: means for transmitting information indicating the set of secondary wireless nodes to the second wireless node, means for selecting the third wireless node among the secondary wireless nodes in the set, and means for transmitting the message for estimating the channel to the third wireless node in response to the selection.

6. The apparatus of claim 4, wherein the apparatus comprises means for: - transmitting to the second wireless node and to the third wireless node a first channel measurement configuration associated with the third wireless node, - transmitting to a fourth wireless node in the set of the second wireless node and secondary wireless nodes a second channel measurement configuration associated with the fourth wireless node, - transmitting to the wireless nodes in the set an instruction to perform channel estimation for the second wireless node, - receiving channel estimation information from said set of secondary wireless nodes, and - generating said security key based on at least some of said received channel estimation information from said set. 7 . The apparatus according to claim 1 , wherein the apparatus is configured to transmit channel measurement resource information associated with the third wireless node to the second wireless node.

8. The apparatus according to any one of claims 1 to 3, wherein the apparatus comprises a component for transmitting a first trigger message to the third wireless node and transmitting a second trigger message to the second wireless node to estimate the channel between the second wireless node and the third wireless node.

9. The apparatus of claim 8, wherein the apparatus comprises means for transmitting the second trigger message after a predetermined waiting period after the transmission of the first trigger message to the third wireless node.

10. An apparatus according to any one of claims 1 to 3, wherein the apparatus comprises a component for transmitting channel estimation timing information to the third wireless node for controlling the timing of a reference signal from the third wireless node to the second wireless node for the estimation of the channel.

11. An apparatus according to any one of claims 1 to 3, wherein the apparatus includes a component for determining the timing information for security key adoption based on one or more of the following information: a return delay, a propagation delay, and a channel state information calculation delay associated with performing the channel estimation between the second wireless node and the third wireless node.

12. An apparatus for a second wireless node, comprising: - means for receiving, from the first wireless node, timing information for security key adoption and information indicative of a third wireless node, - means for receiving channel measurement resource information associated with said third wireless node, - means for receiving a trigger message to estimate a channel between the second wireless node and the third wireless node, - means for generating channel estimation information based on an estimate of the channel in response to the received trigger message and based on the received channel measurement resource information, - means for generating a security key based on said channel estimation information, and - means for applying said security key for encrypted data transmission between said first wireless node and said second wireless node according to said received timing information for security key adoption.

13. The device according to claim 12, wherein the device comprises: Means for receiving a channel state information reference signal from the third wireless node, and means for transmitting a sounding reference signal to the third wireless node based on the received channel measurement resource information.

14. The apparatus according to claim 12 or 13, wherein the apparatus is configured to receive the channel measurement resource information associated with the third wireless node and the trigger message from the first wireless node.

15. The device according to any one of claims 1 to 3 and 12 to 13, wherein the device comprises: Means for encrypting a physical layer message using said security key based on said channel estimation information for physical layer encryption.

16. An apparatus according to any one of claims 1 to 3 and 12 to 13, wherein the timing information for security key adoption indicates a time interval, and the apparatus is configured to apply the security key after the time interval has passed since a trigger message from the first wireless node to the second wireless node for estimating the channel.

17. An apparatus for a third wireless node, comprising: - means for receiving, from a first wireless node, a message for estimating a channel between a second wireless node and said third wireless node, said message for estimating said channel comprising information indicative of said second wireless node and channel measurement resource information associated with said second wireless node, - means for transmitting a reference signal to the second wireless node for directional or omnidirectional channel sensing to estimate the channel between the second wireless node and the third wireless node based on the received channel measurement resource information, - means for generating channel estimation information based on an estimate of said channel, and - A component for transmitting the channel estimation information to the first wireless node for generating a security key for encrypting data between the first wireless node and the second wireless node or transmitting the security key generated by the third wireless node based on the channel estimation information to the first wireless node.

18. The apparatus according to any one of claims 1 to 3, 12 to 13 and 17, wherein the channel measurement resource information comprises a channel state information reference signal and / or a sounding reference signal resource information associated with the third wireless node.

19. An apparatus according to any one of claims 1 to 3, 12 to 13 and 17, wherein the first wireless node and the third wireless node are gNBs or transmission reception points of a 5G radio network, and the second wireless node is a user equipment.

20. The device according to any one of claims 1 to 3, 12 to 13 and 17, wherein the component comprises: At least one processor and at least one memory, the at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause execution of the apparatus.

21. A method for a first wireless node, comprising: - transmitting the timing information of the security key adoption and the information indicating the third wireless node to the second wireless node, - transmitting to the third wireless node a message for estimating a channel between the second wireless node and the third wireless node, the message for estimating the channel comprising information indicating the second wireless node and channel measurement resource information associated with the second wireless node, - obtaining a security key generated based on channel estimation information, the channel estimation information being based on an estimation of the channel by the third wireless node, and - applying the security key to encrypted data transmission between the first wireless node and the second wireless node.

22. The method according to claim 21, comprising - receiving, from the third wireless node, channel estimation information based on an estimation of the channel by the third wireless node, and - generating the security key based on the received channel estimation information.

23. The method of claim 21, comprising receiving the security key from the third wireless node.

24. A method according to any one of claims 21 to 23, comprising: A set of secondary wireless nodes is repeatedly identified that can be used to estimate a channel to the second wireless node, the set including the third wireless node.

25. The method according to claim 24, comprising: - transmitting to the second wireless node information indicating the set of secondary wireless nodes, - selecting the third wireless node among the secondary wireless nodes in the set, and - In response to the selection, transmitting to the third wireless node the message used to estimate the channel.

26. The method according to claim 24, comprising: - transmitting to the second wireless node and to the third wireless node a first channel measurement configuration associated with the third wireless node, - transmitting to a fourth wireless node in the set of the second wireless node and secondary wireless nodes a second channel measurement configuration associated with the fourth wireless node, - transmitting to the wireless nodes in the set an instruction to perform channel estimation for the second wireless node, - receiving channel estimation information from said set of secondary wireless nodes, and - generating said security key based on at least some of said received channel estimation information from said set.

27. A method according to any one of claims 21 to 23, comprising: Channel measurement resource information associated with the third wireless node is transmitted to the second wireless node.

28. A method according to any one of claims 21 to 23, comprising: A first trigger message is transmitted to the third wireless node and a second trigger message is transmitted to the second wireless node to estimate the channel between the second wireless node and the third wireless node.

29. The method according to claim 28, comprising: The second trigger message is transmitted after a predetermined waiting period after the transmission of the first trigger message to the third wireless node.

30. A method according to any one of claims 21 to 23, comprising: Channel estimation timing information is transmitted to the third wireless node for controlling the timing of a reference signal from the third wireless node to the second wireless node for the estimation of the channel.

31. A method according to any one of claims 21 to 23, comprising: The timing information for security key adoption is determined based on one or more of: a backhaul delay, a propagation delay, and a channel state information computation delay associated with performing the channel estimation between the second wireless node and the third wireless node.

32. The method of claim 27, wherein the channel measurement resource information associated with the third wireless node is received from the first wireless node.

33. A method for a second wireless node, comprising: - receiving from the first wireless node timing information for adopting a security key and information indicating a third wireless node, - receiving channel measurement resource information associated with the third wireless node, - receiving a trigger message for estimating a channel between the second wireless node and the third wireless node, - generating channel estimation information based on an estimate of the channel in response to the received trigger message and based on the received channel measurement resource information, - generating a security key based on the channel estimation information, and - applying said security key for encrypted data transmission between said first wireless node and said second wireless node according to said received timing information for security key adoption.

34. The method of claim 33, further comprising: A channel state information reference signal is received from the third wireless node, and a sounding reference signal is transmitted to the third wireless node based on the received channel measurement resource information.

35. The method of any preceding claim 33 or 34, wherein the channel measurement resource information associated with the third wireless node and the trigger message are received from the first wireless node.

36. A method according to any one of claims 21 to 23 and 33 to 34, comprising: A physical layer message is encrypted using the security key based on the channel estimation information used for physical layer encryption.

37. A method according to any one of claims 21 to 23 and 33 to 34, wherein the timing information used for security key adoption indicates a time interval, and the security key is applied after the time interval has passed since a trigger message from the first wireless node to the second wireless node for estimating the channel.

38. A method for a third wireless node, comprising: - receiving a message from the first wireless node for estimating a channel between the second wireless node and the third wireless node, the message for estimating the channel comprising information indicating the second wireless node and channel measurement resource information associated with the second wireless node, - transmitting a reference signal to the second wireless node for directional or omnidirectional channel sensing to estimate the channel between the second wireless node and the third wireless node based on the received channel measurement resource information, - generating channel estimation information based on the estimate of the channel, and -Transmitting the channel estimation information to the first wireless node for generating a security key for encrypting data between the first wireless node and the second wireless node or transmitting the security key generated by the third wireless node based on the channel estimation information to the first wireless node.

39. The method according to any one of claims 21 to 23, 33 to 34 and 38, wherein the channel measurement resource information includes channel state information reference signal and / or sounding reference signal resource information associated with the third wireless node.

40. The method of any one of claims 21 to 23, 33 to 34 and 38, wherein the first wireless node and the third wireless node are gNBs or transmission reception points of a 5G radio network, and the second wireless node is a user equipment.

41. A computer program product, comprising a computer program, which, when executed by a processor, performs the method of any one of claims 21 to 40.

42. A non-transitory computer readable medium comprising instructions which, when executed by at least one processor, cause an apparatus to perform at least the method of any one of claims 21 to 40.

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