CN110753342B - Body area network equipment authentication and key agreement method based on channel characteristics - Google Patents

Abstract

The invention discloses a body area network equipment authentication and key agreement method based on channel characteristics, which mainly comprises five processes of initialization, equipment fingerprint generation, key agreement, key authentication and key updating, and equipment fingerprints are generated by utilizing the randomness of environmental factors and the uniqueness of user behavior characteristics. The initialization procedure is used to establish a preliminary connection of the new device with the control unit in the system. The device fingerprint generation process is used to generate a device fingerprint in preparation for the key agreement and key authentication processes. The key agreement procedure is used to generate a consistent session key between the new device and the control unit. The key authentication process is used to verify whether a device newly added to the system is a secure device. The key updating process is used for generating uniform session keys for all body area network devices in the system and updating in time, so that the communication safety and the lightweight of a key agreement protocol are ensured. The body area network equipment safety authentication method provided by the invention is more convenient, effective, safe and reliable.

Description

A body area network device authentication and key agreement method based on channel characteristics

technical field

The invention belongs to the technical field of Internet of Things communication, relates to a channel feature-based body area network device authentication and key negotiation method, and in particular relates to a body area network device authentication and key negotiation based on channel features based on environmental context and user behavior method.

Background technique

With the continuous development of Internet of Things technology and the maturity of Internet technology, it has become a reality that various Internet of Things devices such as home appliances, daily necessities, and wearable devices are connected to the network. As an important part of the Internet of Things, body area network is widely used in medical, health care, sports, consumer electronics and other fields, and has a very broad application prospect. Common body area network devices mainly include smart bracelets, smart glasses, smart running shoes, and some portable or implantable devices that can collect various physiological parameters of the human body (eg, electrocardiogram, blood pressure, pulse, etc.). The popularization of body area network equipment not only improves people's quality of life, but also improves people's medical care level. However, while these body area network devices provide users with convenience, there are also certain security risks. The processing power of body area network devices is limited, and the data created by the device often contains privacy-sensitive information about user activity and user health. Once obtained by an attacker, it will cause irreversible effects.

In order to ensure the communication security between body area network devices, when a new body area network device is added, it is necessary to perform security authentication with the existing device through an encryption key to avoid man-in-the-middle attacks and protocol manipulation attacks. The traditional security authentication protocol requires the user to perform manual operation. For example, when using Bluetooth or wireless network for device authentication, the user needs to manually enter a password for authentication. This method requires the device to have an interactive interface to complete the authentication, and manual pairing by the user will also increase the user's burden of use and learning. While it is possible to configure a body area network device with preloaded keys, an interactive interface, or dedicated pairing hardware (eg, NFC), these approaches can overburden the device manufacturer and increase the cost of the device.

The environmental context-based authentication method can make up for the shortcomings of traditional security authentication protocols. Using the characteristics that devices existing in the same environment will perceive similar environmental information, and generate similar device fingerprints based on similar signal changes detected by the device. verify. In the body area network scenario, the sensor types of the device are often diverse, and it is very difficult to process the data of different types of signals collected by heterogeneous sensors to generate device fingerprints.

In addition, in the body area network system, pairing of devices can realize communication, but when communicating with a device that is not directly paired, it is necessary to transmit information through other devices that have been paired, which will increase the storage cost of the device and communication costs.

SUMMARY OF THE INVENTION

In order to solve the above technical problems, the present invention provides a channel feature-based body area network device authentication and key agreement method based on environmental context and user behavior, which can avoid the problem of difficult data processing caused by different types of device sensors, It realizes the authentication of the body area network equipment worn by the same user and the negotiation of the unified session key, and does not require manual operation of the user for authentication, which reduces the burden on the user and increases its practicability.

The technical scheme adopted in the present invention is: a method for authentication and key agreement of a body area network device based on channel characteristics, which is characterized in that it includes the following steps:

Step 1: Establish a preliminary connection between the new device and the control unit in the system;

The control unit refers to a mobile intelligent device, which is used to summarize the physiological signals collected by all sensor devices in the system and forward it to the server for processing;

Step 2: Generate new device and control unit fingerprints;

According to the randomness and uniqueness of user behavior characteristics and the similarity of channel environment, new device and control unit fingerprints are generated;

Step 3: key negotiation;

Generate a consistent session key between the new device and the control unit, and negotiate the session key through the device fingerprints generated by each;

Step 4: key authentication;

Verify whether the new device newly added to the system is a security device worn by the same user, and whether it is a security device is verified by using the device fingerprint generated by the new device; among the devices worn by the same user, the relative distance between the two changes and The channel environment is consistent;

Step 5: Key update;

Generate a unified session key for all body area network devices in the system and update it in time to ensure communication security.

Compared with the prior art, the advantages and positive effects of the present invention are mainly reflected in the following aspects:

Compared with the prior art, the advantages and positive effects of the present invention are mainly reflected in the following aspects:

(1) It can eliminate the need for advanced hardware and human participation in the process of body area network device authentication and key agreement. Compared with the traditional method, it is suitable for more scenarios and reduces the burden on users.

(2) It generates device fingerprints based on the similarity of channel characteristics between the body area network devices carried by the same user. Due to environmental factors and the uniqueness and randomness of user activity behavior, the channel characteristics improve the entropy of key extraction and ensure that security.

(3) It can authenticate whether the device is trustworthy, and generate a unified session key for all the body area network devices in the system, which ensures the communication security in the body area network system and saves the storage resources of the device.

Description of drawings

1 is a flowchart of an embodiment of the present invention;

FIG. 2 is a detailed diagram illustrating steps of five processes in an embodiment of the present invention.

Detailed ways

In order to facilitate the understanding and implementation of the present invention by those skilled in the art, the present invention will be described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the embodiments described herein are only used to illustrate and explain the present invention, not The invention is limited.

Referring to FIG. 1 , a method for authentication and key negotiation of a body area network device based on channel characteristics provided by the present invention mainly includes five processes: initialization, device fingerprint generation, key negotiation, key authentication and key update. The initialization process is used to establish a preliminary connection between the new device and the control unit in the system. The device fingerprint generation process is used to generate the device fingerprint to prepare for the key negotiation and key authentication process. The main idea of device fingerprint generation is based on the following three points: (1) RSS fluctuations usually occur in wireless channels due to environmental factors and human motion; (2) the channel characteristics between two devices worn by the same user are consistent within the coherence time. (3) The behavior characteristics of users are unpredictable and unique, and are not easy to be predicted and replicated. The key negotiation process is used to generate a consistent session key between the new device and the control unit, and negotiate the shared encryption key through the device fingerprints generated by each. The key authentication process is used to verify whether the device newly added to the system is a security device worn by the same user, and whether it is a security device is verified by using the device fingerprint generated by the new device. The key update process is used to generate a unified encryption key for all body area network devices in the system and update it in time to ensure communication security.

In this embodiment, each device in the body area network system has a unique device ID, a trusted control unit exists in the system, and the session key of the system is K. When a new device N joins the system, it needs to generate the device fingerprint F_N first, then perform key negotiation with the control unit, and after negotiating the session key, perform key authentication to verify whether the new device N is a trusted device, and finally calculate the new device N through key update. session key.

See Fig. 2, the realization of the present invention specifically comprises the following steps:

Step 1: Establish a preliminary connection between the new device and the control unit in the system;

In this embodiment, the control unit usually refers to a mobile smart device such as a smart phone and a smart tablet, and is used to summarize the physiological signals collected by all sensor devices in the system and forward it to the server for processing.

In this embodiment, the specific implementation of step 1 includes the following sub-steps:

Step 1.1: The user places the new device N in a safe area and performs normal activities; for example, walking, eating, running, etc.

In this embodiment, the security zone refers to the same body area network (ie, on the same user), which is used to separate the trusted device from the external devices or attacker devices of other body area networks. The user's activity behavior can bring more uncertainties to the channel characteristics, so that the collected RSS data values have enough volatility and provide enough entropy for fingerprint extraction.

Step 1.2: The new device N that wants to join the system sends out a broadcast message, the message contains the new device identity ID _N and the request pairing message Request_To_Pair;

Step 1.3: The control unit A in the system receives the message, and sends the pairing response message Response_To_Pair and the identity ID _A to the new device N.

Step 2: Generate new device and control unit fingerprints;

According to the randomness and uniqueness of user behavior characteristics and the similarity of channel environment, new device and control unit fingerprints are generated;

In this embodiment, the specific implementation of step 2 includes the following sub-steps:

Step 2.1: The control unit A sends a message M=(x, t ₀ , t) to the new device N, where x, t ₀ , t respectively represent a certain time, and its value is preset;

Step 2.2: After receiving the message x seconds, the new device N sends a detection message m to the control unit A every t milliseconds for t ₀ seconds; at this time, the control unit A can collect a group of continuous RSS values through the detection message; where t is greater than the coherence time between devices;

Step 2.3: the control unit A responds to each probe message within the coherence time, and repeatedly responds to the same message m; at this time, the new device N can collect a group of continuous RSS values through the response message;

Step 2.4: The new device N and the control unit A quantify the collected RSS values through a quantizer to obtain two bit sequences, namely the device fingerprint F _N of the new device and the device fingerprint F _A of the control unit.

In this embodiment, the quantizer refers to extracting the bit sequence of the device fingerprint from the RSS measurement value using the method based on lossy quantization; using the Mathu quantization method, two thresholds q ⁺ and q ⁻ are used, q ⁺ =mean+ α*std _deviation , q ^- = mean-α*std _deviation , where mean is the average value of the collected data, α is a configurable adjustment parameter, 0<α<1, and std _deviation is the standard deviation; in the Mathu quantification method, First, discard the values less than q ⁺ and greater than q ^- in the collected RSS data set, and secondly, for the remaining data, if it is greater than q ⁺ , it is set to 1, and if it is less than q ^- , it is set to 0, so as to realize the quantification of the RSS value. The bit sequence of the device fingerprint.

Due to factors such as different device hardware, the device fingerprint bit sequences generated by the two devices will not be exactly the same, and a unified shared encryption key needs to be negotiated through process three.

Step 3: key negotiation;

Generate a consistent session key between the new device and the control unit, and negotiate the session key through the device fingerprints generated by each;

In this embodiment, the specific implementation of step 3 includes the following sub-steps:

其中

代表在一个有限域中的减法，等价于XOR运算；Step 3.1: The control unit A generates the random key k and encodes it to obtain the codeword ENC(k), wherein ENC() is the encoding function of the error correction code, and the error correction code uses the RS code; then, utilize the control unit fingerprint F _A computing commitment

in

Represents subtraction in a finite field, equivalent to the XOR operation;

Step 3.2: Control unit A sends C _A and h(k) to device N, where h() is a collision-resistant hash function, using the SHA-3 hash function, which does not reveal information about the key k or the fingerprint any information on F _A ;

获得相应的

其中，DEC()为互补解码函数；需要强调的是，当F_N和F_A的汉明距离在解码能力范围内时，设备N计算得到的

才能与控制单元产生的随机密钥k相等；Step 3.3: When the new device N receives the information, it tries to use the new device fingerprint F _N to open the commitment C _A to obtain the random key k; the new device N passes the formula

get the corresponding

Among them, DEC() is the complementary decoding function; it should be emphasized that when the Hamming distance of F _N and F _A is within the decoding capability range, the calculated value of device N

can be equal to the random key k generated by the control unit;

此时，控制单元A不知道设备N创建的共享密钥

需要通过下面的密钥认证过程进行确认。Step 3.4: The new device N uses the key derivation function KDF() to generate a symmetric key shared with the control unit A

At this point, the control unit A does not know the shared key created by the device N

Confirmation is required through the following key authentication process.

Step 4: key authentication;

Verify whether the new device N newly added to the system is a security device worn by the same user, and whether it is a security device is verified by using the device fingerprint generated by the new device; among which, the relative distance between the devices worn by the same user changes and the channel environment is consistent;

In this embodiment, the specific implementation of step 4 includes the following sub-steps:

即利用密钥

加密随机数n_N；Step 4.1: The new device N generates a random number n _N and calculates the message verification code

using the key

encrypted random number n _N ;

n_N，

发送给控制单元A；Step 4.2: The new device N will

n _N ,

Send to control unit A;

是否与h(k)相等；若

控制单元A通过公式k_AN＝KDF(k)推导出与新设备N的共享密钥k_AN，否则终止协议，配对失败；然后判断消息验证码M(k_AN(n_N))与

是否相等，对密钥

进行验证；若相等，则A产生一个随机数n_A，并计算M(k_AN(n_N||n_A))，否则协议终止，配对失败；Step 4.3: After control unit A receives the message, it first verifies

Is it equal to h(k); if

The control unit A derives the shared key k _AN with the new device N through the formula k _AN =KDF(k), otherwise the protocol is terminated and the pairing fails; then it is judged that the message verification code M(k _AN (n _N )) and the

Is it equal to the key

Verify; if they are equal, A generates a random number n _A and calculates M(k _AN (n _N ||n _A )), otherwise the protocol terminates and the pairing fails;

Step 4.4: A sends the random number n _A and the message verification code M (k _AN (n _N ||n _A )) to N;

是否相等，若相等则A与N成功建立一个共享密钥k_AN，否则协议终止，配对失败。Step 4.5: The new device N verifies that M(k _AN (n _N ||n _A )) and

If they are equal, A and N successfully establish a shared key k _AN , otherwise the protocol terminates and the pairing fails.

Step 5: Key update;

Generate a unified session key for all body area network devices in the system and update it in time to ensure communication security;

In this embodiment, the specific implementation of step 5 includes the following sub-steps:

Step 5.1: the control unit A utilizes the system session key K before the new device N joins to encrypt the shared key k _AN , namely E _K (k _AN ); wherein, E( ) is an AES encryption function;

Step 5.2: the control unit A sends E _K (k _AN ) to all other trusted body area network devices TD _s in the system;

Step 5.3: After receiving the message, all other trusted body area network devices TDs in the system decrypt to obtain a new session key K′=D _K ( _{k AN} ) of the system, and complete the key update; where D() is AES decryption function.

The present invention considers the situation that the session key cannot be updated when no new device joins for a long time. In order to ensure the security of the session key, two mechanisms for updating the key are proposed: (1) Count the data packets sent by the devices in the system when communicating, and update the current session key when it reaches a certain number; ( 2) A timer is added to the system to update the current session key at regular intervals. The update method can be obtained by calculating the current session key K and the random number n.

In terms of security, attackers can steal user privacy-sensitive information by eavesdropping on communications between body area network devices. To achieve this, attackers can launch brute force attacks, shaming attacks or man-in-the-middle attacks in-the-middle attack). Brute-force attack: An attacker attempts to crack a key directly from the key's hash value by exploiting a hash dictionary attack. Spoofing attack: An attacker's device is placed outside a secure area but within wireless communication range, attempting to spoof a control unit device within a secure area. Attacker devices can imitate the user's behavior by attempting to imitate the user's behavior outside of a safe area close to the user; in addition, the attacker can also initiate a man-in-the-middle attack by intercepting the communication messages between the devices during the key negotiation phase

For brute force attacks, the commitment value is sent together with the hash value during transmission. As long as the hash length of the key is longer than the length of the key, brute force cracking is computationally infeasible in theory. In the present invention, the SHA-3 algorithm is used for encryption, and the defined number of bits of the fingerprint is 112, so the length of the hash value is larger than 112, that is, it is secure to a certain extent.

For spoofing attacks, due to the unpredictability of environmental factors and the uniqueness of user behavior, it is difficult for attackers to generate similar device fingerprints by imitating user behavior. Therefore, it can be judged whether the device is in the same environment as the trusted device by verifying the device fingerprint, so as to avoid the spoofing attack of the attacker.

For the man-in-the-middle attack, the present invention uses the fuzzy promise to perform key negotiation to generate the session key, which can effectively prevent the man-in-the-middle attack.

It should be understood that the parts not described in detail in this specification belong to the prior art; the above description of the preferred embodiments is relatively detailed, and therefore should not be considered as a limitation on the protection scope of the patent of the present invention. Under the inspiration of the present invention, without departing from the scope of protection of the claims of the present invention, substitutions or modifications can also be made, which all fall within the scope of protection of the present invention. Requirements shall prevail.

Claims (3)

1. A body area network equipment authentication and key agreement method based on channel characteristics is characterized by comprising the following steps:

step 1: establishing a preliminary connection between the new device and a control unit in the system;

the control unit refers to a mobile intelligent device and is used for summarizing physiological signals acquired by all sensor devices in the system and forwarding the physiological signals to a server for processing;

the specific implementation of the step 1 comprises the following substeps:

step 1.1: the user places the new device N in a safe area to carry out normal activities; the security zone is in the same body area network, namely on the same user, and is used for separating the trusted device from external devices or attacker devices of other body area networks;

step 1.2: the new equipment N which wants to join the system sends out a broadcast message which contains the ID of the new equipment_NAnd Request pairing message Request _ To _ Pair;

step 1.3: the control unit A in the system receives the message and sends a pairing Response message Response _ To _ Pair and the ID To the new device N_A；

Step 2: generating a new device and control unit fingerprint;

generating new equipment and control unit fingerprints according to randomness and uniqueness of user behavior characteristics and similarity of channel environments;

the specific implementation of the step 2 comprises the following substeps:

step 2.1: the control unit A sends a message M ═ x, t to the new device N₀T), where x, t₀T represents a certain time, respectively, the value of which is set in advance;

step 2.2: after receiving the message for x seconds, the new device N sends a detection message m to the control unit A every t milliseconds for t₀Second; at this time, the control unit a can collect a set of continuous RSS values through the probe message; where t is greater than the coherence time between devices;

step 2.3: the control unit A responds to each detection message within the coherence time and repeatedly responds to the same message m; at this point, the new device N is able to collect a set of consecutive RSS values through the response message;

step 2.4: the new device N and the control unit A quantize the collected RSS values through a quantizer to respectively obtain two bit sequences, namely a device fingerprint F of the new device_NAnd controlDevice fingerprint F of a unit_A；

And step 3: key agreement;

generating a consistent session key between the new device and the control unit, and negotiating the session key by the device fingerprints generated respectively;

the specific implementation of the step 3 comprises the following substeps:

step 3.1: the control unit A generates a random key k and encodes the random key k to obtain a code word ENC (k), wherein ENC () is an encoding function of an error correcting code, and the error correcting code uses an RS code; then, using the control unit fingerprint F_AComputing commitments

Wherein

Represents a subtraction in a finite field, equivalent to an XOR operation;

step 3.2: control unit A sends C to device N_AAnd h (k), wherein h () is a collision-resistant hash function, employing the SHA-3 hash function;

step 3.3: when the new device N receives the information, it attempts to use the new device fingerprint F_NOpen promise C_ATo obtain a random key k; new device N by formula

Obtain corresponding

Wherein DEC () is a complementary decoding function; wherein, when F_NAnd F_AWhen the Hamming distance is within the decoding capability range, the device N calculates

Can it be equal to the random key k generated by the control unit;

step 3.4: the new device N generates an AND control sheet using a key derivation function KDF ()Meta-A shared symmetric key

And 4, step 4: key authentication;

verifying whether new equipment newly added into the system is safety equipment worn by the same user or not, and verifying and judging whether the new equipment is the safety equipment or not by utilizing an equipment fingerprint generated by the new equipment; the relative distance change and the channel environment of the equipment worn by the same user are consistent;

the specific implementation of the step 4 comprises the following substeps:

step 4.1: the new device N generates a random number N_NAnd calculates a message authentication code

I.e. using a secret key

Encrypting a random number n_N；

Step 4.2: new device N will

Sending the data to a control unit A;

step 4.3: after receiving the message, the control unit A firstly verifies

Is equal to h (k); if it is

The control unit A passes the formula k_ANKdf (k) derives a shared key k with the new device N_ANOtherwise, terminating the protocol and failing to pair; then judging the message verification code M (k)_AN(n_N) Are) and

whether or not to be in phaseEtc. to the secret key

Carrying out verification; if equal, A generates a random number n_AAnd calculating M (k)_AN(n_N||n_A) Else, the protocol is terminated and the pairing is failed;

step 4.4: a is random number n_AAnd message authentication code M (k)_AN(n_N||n_A) To N;

step 4.5: new device N verifies M (k)_AN(n_N||n_A) Are) and

whether they are equal, if so, A and N successfully establish a shared secret key k_ANOtherwise, the protocol is terminated and the pairing is failed;

and 5: updating a secret key;

and a uniform session key is generated for all body area network devices in the system and is updated in time, so that the communication safety is ensured.

2. The method for body area network device authentication and key agreement based on channel characteristics as claimed in claim 1, wherein: in step 2.4, the quantizer is to extract a bit sequence of the device fingerprint from the RSS measurement value by using a method based on lossy quantization; using the Mathu quantization method, two thresholds q are used⁺And q is^-，q⁺＝mean+α*std_deviation，q^-＝mean-α*std_deviationWhere mean is the average of the collected data, α is a configurable adjustment parameter, α is greater than 0 and less than 1, std_deviationIs the standard deviation; in the Mathu quantization method, less than q of the collected RSS data sets are first discarded⁺And is greater than q^-If it is greater than q, then for the remaining data⁺Is set to 1 if less than q^-Is set to 0 to achieve the RSS value quantization resulting in a bit sequence of the device fingerprint.

3. The method for authenticating and negotiating keys for body area network devices according to claim 1 or 2, wherein the step 5 comprises the following sub-steps:

step 5.1: the control unit A encrypts the shared secret key K by using the system session secret key K before the new equipment N is added_ANI.e. E_K(k_AN) (ii) a Wherein E () is an AES encryption function;

step 5.2: the control unit A will E_K(k_AN) To all other trusted body area network devices TD in the system_s；

Step 5.3: all other trusted body area network devices TD in the system_sAfter receiving the message, the decryption obtains a new session key K' ═ D of the system_K(k_AN) Completing the updating of the secret key; where D () is the AES decryption function.

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