Identity authentication method and device based on covert channel and application

Abstract

The invention relates to the technical field of communication, in particular to the problem of reliable identity authentication in the technical field of communication, and particularly relates to an identity authentication method and device based on a covert channel and application, and the identity authentication method comprises the following steps: transmitting user identity information used for verification in the covert channel or a public channel, meanwhile, false identity information with misleading or even inductivity is generated and transmitted in a channel in a confusion mode, an attacker can only intercept false identity information and communication data, and the purpose of privacy protection is achieved. Then the secret key is split and transmitted in two channels, the secret key management capability is enhanced, and the secret key interception difficulty is greatly improved; and in the encryption communication stage, some short label information is embedded in the covert channel to continuously authenticate the client, so that the safety of the whole communication process is ensured. And the secret key is re-negotiated and replaced when a certain amount of data is transmitted or important information needs to be transmitted by using the covert channel, so that the security of communication data is improved. Finally, the invention further provides a covert channel construction method based on the time delay sequence between the data packets.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, in particular to the problem of reliable identity authentication in the field of communication technology, and specifically to a covert channel-based identity authentication method, device and application. Background Art

[0002] User communication data information is extremely vulnerable to being intercepted, eavesdropped and tampered by attackers, so identity authentication methods must be used to verify the legitimacy of the identities of both parties in communication, thereby ensuring the security of communication data. Existing technologies mostly use encryption methods for secure communication, and generate session keys through processes such as user authentication and key negotiation to encrypt subsequent communication data content, thereby providing secure and reliable communication services. However, with the development of computing power, keys have become easier to crack, and too complex keys will consume a lot of resources and reduce efficiency. On the other hand, the field of identity authentication has only used public channels to transmit keys, user identities and other important and sensitive information. Due to its open nature, it is still intercepted, eavesdropped and tampered by attackers, which can easily expose user privacy.

[0003] Compared with open channels, network covert channels are a technology that uses network characteristics to embed information to establish a covert communication channel and use it to transmit data. Covert channels are divided into covert storage channels and covert timing channels. For example, by changing the delay interval of data packets to represent different bits, information can be embedded for covert transmission. Manipulating the network data packet time interval to become longer can represent bit "1", and a shorter data packet time interval represents bit "0". Another covert storage channel can be achieved by changing the length of the data packet, or embedding information inside the data unit, protocol header, etc., for example: embedding information in certain fields of the IP protocol header and TCP protocol header. Among them, the covert storage channel has a larger channel capacity, better robustness, and is less affected by changes in network status, but has poor concealment and is easy to detect; while the covert timing channel has better concealment and is difficult to detect, but the channel capacity is small, it is easily affected by changes in network status, and has low robustness.

[0004] To sum up, if the existing technology only focuses on longer keys and more complex encryption algorithms, it will still face problems such as public channel exposure, key distribution management, and high computational overhead. Summary of the invention

[0005] The purpose of the present invention is to propose an identity authentication mechanism based on a covert channel to provide a more stringent authentication system for the client and the server. In view of the shortcomings of the existing identity authentication mechanism in the background technology, the identity authentication is combined with the covert channel to make up for the above shortcomings, provide a new solution for authentication encryption, and improve the security of the communication process. The present invention is no longer limited to using an open channel to transmit all information such as user identity, keys, data, etc., but combines the open channel with the covert channel, ultimately achieving a safer and more reliable identity authentication, and ensuring the communication security of the entire process through continuous authentication.

[0006] The first aspect of the present invention provides an identity authentication method based on a covert channel, comprising the following steps:

[0007] First, the user identity information used for verification is transmitted in a covert channel, and misleading or even inductive forged identity information is generated and transmitted in an open channel. Attackers can only intercept fake identity information and communication data, thereby achieving the purpose of privacy protection. By extension, true and false identity information can be randomly selected and transmitted in the open channel and the covert channel. The receiving end only needs to verify one real identity information. This is no longer fixed to a certain channel to transmit certain information, and can better ensure data privacy and security. Then the key is split and transmitted in two channels. This increases the security of key transmission and enhances key management capabilities. If an attacker wants to obtain the key, he must intercept all information in the two channels and know the rules for key reorganization and recovery. The difficulty of key interception is greatly increased, which makes up for the shortcomings of key transmission security in identity authentication. In the final encrypted communication stage, some short tag information is embedded in the covert channel to continuously authenticate the client to ensure the security of the entire communication process. In addition, the covert channel can also be used to renegotiate and replace the key when a certain amount of data is transmitted or important information is to be transmitted, thereby improving the security of communication data.

[0008] According to a second aspect of the present invention, there is provided an identity device based on a covert channel, comprising: an identity authentication client and an identity authentication server, wherein a covert channel and an open channel are constructed between the identity authentication client and the identity authentication server;

[0009] The covert channel and the public channel transmit user identity information for verification and misleading forged identity information; and are used to transmit the split keys respectively.

[0010] The covert channel is also used to transmit short tag information for continuous authentication.

[0011] As a further improvement, the identity authentication client and the identity authentication server both include: an identity information hiding module, a key transmission module, a continuous verification module, a hidden information embedding module, and a hidden information extraction module;

[0012] The identity information hiding module, key transmission module, and continuous verification module are responsible for generating the required corresponding information, determining the corresponding information to be transmitted in the channel, and the next task execution plan after receiving the information; the hidden information embedding module and the hidden information extraction module are used to embed information into the hidden channel or extract it from it.

[0013] As a further improvement, the identity information hiding module is used to generate false identity information and false key parameter information, and to generate a rule for encoding or splitting the key.

[0014] As a further improvement, the identity authentication client and the identity authentication server perform the following collaboration to complete the identity authentication;

[0015] Initialization phase: The client establishes a communication connection with the server, sends an identity authentication request to the server, uses the hidden information embedding module to transmit the user identity information to be used for verification in the covert channel, and transmits the identity information forged by the identity information hiding module and the false key parameter information in the public channel; for further improvement, the public channel and the covert channel can randomly select to transmit true and false identity information, and the server only needs to verify a complete and real identity information. In this way, it is no longer fixed to a certain channel to transmit certain information, and the user information can be transmitted by splitting or obfuscating methods, which can better ensure data privacy and security.

[0016] Authentication stage: used to implement identity authentication between the client and the server. After receiving the authentication request, the server verifies the identity information of the client and checks whether the client is registered. If not, the authentication fails if the client is an illegal user. If the identity information is valid, the authentication succeeds. Then the server uses the key transmission module to generate fake communication information and the real key parameters. Then, according to the encoding splitting rules received from the client, the real key parameters are split to obtain two split key parameters for transmission.

[0017] Key exchange stage: after receiving the two split key parameters from the two channels, the client decodes and recovers the key according to the encoding splitting rule to obtain the communication session key used for the next communication session; the above communication session key is split according to the encoding splitting rule to obtain two split communication session keys, which are transmitted in the public channel and the covert channel respectively;

[0018] Encrypted communication stage: After the server receives all the information, it will restore and splice the two split communication session keys into a communication key according to the encoding splitting rule; then the server and the client will use the communication key as the communication session key to encrypt and transmit data in a public channel.

[0019] As a further improvement, during the encrypted communication phase, a short tag is generated by the continuous verification module as a subsequent lightweight authentication identifier, and then the continuous verification phase is entered. After receiving the short tag, the client embeds it into the covert channel and transmits the data of the public channel simultaneously; at this time, if an attacker attempts to join the communication process to perform a man-in-the-middle attack, forgery attack, etc., since its covert channel does not contain the short tag, it will be detected and warned by the continuous verification module when it establishes a communication connection with the client and the server.

[0020] As a further improvement, the information transmission path can be changed to the public channel being used to transmit user identity information to be used for verification, and the covert channel being used to transmit misleading forged identity information.

[0021] According to a third aspect of the present invention, a covert channel construction method based on the delay sequence between data packets is provided, comprising: establishing a covert channel to embed information and transmit data by adjusting the delay sequence between data packets. Different from other covert channel methods, this method does not change the absolute size of the delay between data packets, the centroid of the time slot, etc., retains the original sequence characteristics, and changes the relative size by exchanging the order to carry information and embed data.

[0022] The present invention also provides applications of the above method or device, such as application in drone identity authentication and application in FTP platform identity authentication.

[0023] The application of the technical solution of the present invention has the following technical effects:

[0024] (1) Protecting user identity information. The present invention transmits the identity information in the authentication process in one channel and transmits misleading or inducing false identity information in another channel, making it impossible for attackers to distinguish the authenticity, thereby achieving the effect of protecting the user's identity privacy.

[0025] (2) Strengthen key management and enhance the security of key transmission. The present invention splits the key into two parts for transmission. The attacker must intercept the information of two channels at the same time and know the rules for reorganizing and recovering the key in order to completely restore the key information. This can greatly increase the difficulty of key interception and make up for the shortcomings of key transmission security in identity authentication.

[0026] (3) Improving the reliability of identity authentication. The present invention utilizes covert channels and explicit channels to transmit important information such as user identity information and communication keys, combining the advantages of covert channels with identity authentication to provide a stricter and more reliable identity authentication solution.

[0027] (4) Improve the security of the entire communication process. In the encrypted communication stage, the present invention can still choose to embed a short tag in the covert channel for authentication to ensure the security of the entire communication process. Once interception, forgery, man-in-the-middle and other attacks occur, the authentication of the covert channel will be affected. If highly reliable and secure communication is to be ensured, this method can be selected to ensure the security of the entire communication process with less overhead.

[0028] (5) The present invention provides a covert information embedding algorithm based on the delay sequence between data packets. Information can be embedded by simply adjusting the sequence of the delay between data packets without changing their absolute size, thereby increasing the covert channel capacity and concealment and reducing overhead. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0030] Figure 1 The overall architecture diagram of the present invention is shown;

[0031] Figure 2 The process diagram of completing the identity authentication flow of the present invention is shown;

[0032] Figure 3 A certification diagram of drone deployment in a smart city scenario using the present invention is shown;

[0033] Figure 4 A schematic diagram of FTP platform identity authentication using the present invention is shown. DETAILED DESCRIPTION

[0034] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0035] Example 1

[0036] The embodiment of the present invention provides an identity authentication method based on a covert channel. Most authentication schemes include five stages: initialization, client-server identity authentication, key negotiation, encrypted communication, and continuous verification. This embodiment can be combined with a variety of different identity authentication schemes, and work on the basis of the five stages, using covert channels to achieve user privacy protection and key protection, and ensure communication security. Specifically, the real user identity information and key are transmitted in a confused manner using covert channels and public channels. The attacker must decode the information of the two channels to fully obtain the user identity, key, and communication data, which can protect the privacy of the user identity, protect the security of key transmission, and ensure the security of communication authentication.

[0037] Initialization phase of the covert channel-based authentication method: This phase is used by the client to make an identity authentication request and generate key parameters to prepare for negotiating keys and subsequent encrypted communications. The client chooses to transmit real identity information and key parameter information in a covert channel or an open channel, and then transmits false identity information and key parameter information in another channel. By using open channels and covert channels to split and confuse the transmission of true and false information, attackers cannot determine which channel transmits the real information. Even if all channel information is intercepted, it is still impossible to determine the true or false, and may even be misled by false information, and thus unable to launch an attack.

[0038] Client-server authentication phase: This phase is used to implement authentication between the client and the server. After receiving the authentication request, the server verifies the client's identity information and checks whether the client is registered. If not, it is an illegal user. If the identity information is valid, some false communication information is generated, such as false keys, false task information, etc., which are transmitted in the public channel, and the real key parameters are split according to certain rules and transmitted in two channels. This operation increases the difficulty for attackers to crack the key and enhances the security of key transmission.

[0039] Key exchange phase: This phase is used to implement key exchange and negotiation between the client and the server, and determine the key for subsequent encrypted communication. After receiving the above-mentioned real key parameters, the server calculates the key and continues to split it into two parts and transmits them in two channels respectively. This operation increases the difficulty for attackers to crack the key and enhances the security of key transmission.

[0040] Encrypted communication phase: This phase is used by both parties to recover the complete key and continue encrypted communication to transmit data. This phase also generates a short tag for lightweight authentication in the subsequent communication process to ensure the security of the entire communication process.

[0041] Continuous verification phase: In this phase, short tags are embedded in covert channels to perform continuous lightweight authentication on the client. At the same time, key replacement rules can also be used in this phase to replace keys when a certain amount of data is transmitted or when important information is about to be transmitted. It must be emphasized that the present invention does not mean that only 5 stages of identity authentication are included, nor does it focus on how identity information is calculated and encrypted, and how keys are calculated and generated. The focus of the present invention is to use covert channels to strengthen identity authentication during the transmission process. Therefore, this patent can be combined with a variety of different identity authentication schemes and flexibly deployed according to different scenarios and needs. The corresponding modules and stages can be reduced according to user overhead and required functions, and different key calculation, encryption communication and other methods can also be applied. This patent can be deployed independently for identity authentication, or it can be deployed in the 5 stages of the traditional authentication algorithm. This patent is used to provide privacy protection, key transmission protection and continuous authentication, and provide highly reliable identity authentication, which also does not affect the uniqueness and innovation of the identity authentication mechanism of this patent.

[0042] It also includes an algorithm for establishing a covert channel based on the delay sequence between data packets to embed key information. The core idea of ​​the algorithm is to not change the absolute value of the delay sequence between data packets, and to establish a covert channel to embed information and transmit data by adjusting the delay sequence between data packets. It must be emphasized that this patent proposes a method for establishing a covert channel based on the delay sequence between data packets, which does not mean that the above-mentioned identity authentication process can only adopt this method to establish a covert channel so that the identity authentication mechanism can work normally. A variety of technologies for establishing covert channels can be applied to the above-mentioned identity authentication process, and are not limited to a certain method of embedding covert channel information. They can be combined with multiple methods to embed and establish a covert channel to embed hidden information, and can be flexibly deployed in the covert information embedding module and the covert information extraction module according to different scenarios and overheads. It also does not affect the uniqueness and innovation of the identity authentication mechanism.

[0043] Example 2

[0044] The embodiment of the present invention provides an identity authentication device based on a covert channel. The overall architecture of the present invention is shown in FIG. Figure 1 As shown in the figure, the identity authentication client and server are composed of an identity information hiding module, a key transmission module, a continuous verification module, a hidden information embedding module, and a hidden information extraction module. The identity information hiding module, the key transmission module, and the continuous verification module are responsible for generating the required information, determining which channel to transmit the corresponding information, and the next task execution plan after receiving the information. The hidden information embedding module and the hidden information extraction module use corresponding methods to embed information into the hidden channel or extract it from it.

[0045] The identity authentication flow chart of the present invention is as follows Figure 2As shown, the authentication scheme can work in five stages, namely (1) initialization stage, (2) client-server identity authentication stage, (3) key negotiation stage, (4) encrypted communication stage, and (5) continuous verification stage. Before the authentication scheme runs, all clients in the system have registered with the server. The detailed workflow of all stages is described below. It is worth noting that the present invention does not mean that it is limited to simply including five stages, nor does it focus on how the identity information is calculated and encrypted, and how the key is calculated and generated. The advantage of the present invention is that it uses a covert channel to strengthen the identity authentication during the transmission process. Therefore, this patent can be combined with a variety of different identity authentication schemes and work on the basis of five stages. The application of this patent provides privacy protection, key transmission protection and continuous authentication, and provides highly reliable identity authentication. At the same time, the identity authentication process proposed in this part of the patent is not limited to a certain covert channel information embedding method. It can be combined with a variety of methods to embed and thus establish a covert channel embedded hidden information, and can be flexibly deployed in the covert information embedding module and the covert information extraction module according to different scenarios and overheads.

[0046] (1) Initialization phase: In this phase, each client has registered with the server. The server has the identity information of the legitimate registered user and now needs to authenticate with the server and negotiate the session key. First, the client establishes a communication connection with the server and sends an identity authentication request to the server. Different from the traditional authentication method, the client uses the identity information hiding module to generate fake identity information FI and fake key parameter information FP. A , and transmit these false messages in the open channel. The hidden information embedding module is used to transmit the client's real identity information RI in the covert channel. At the same time, in order to prepare for the subsequent key negotiation, the key transmission module also generates a rule KDR for encoding or splitting the key, which is embedded in the covert channel through the hidden information embedding module and then transmitted to the server. The purpose of the above approach is to prevent the identity information of the user or device from being transmitted in the open channel and reduce the risk of exposure. From the attacker's point of view, it is still a normal communication process on the surface. Even the intercepted information is still false identity information. It can even be used to mislead the attacker and complete the reverse attack on the attacker.

[0047] As a further extension, the client can decide on which channel to transmit the above-mentioned real information. After receiving the information, the server only needs to verify that a user identity is registered. This is more flexible while achieving the same purpose. Unlike the above process, the covert channel is specified to transmit information. In this way, the attacker will use all resources to attack the covert channel. The channel for transmitting real information is randomly selected. Even if the attacker has the ability to obtain information from two channels, he cannot distinguish which one is the real identity information, thereby increasing the difficulty of intercepting identity information and protecting user privacy. It is worth noting that for this method and system, the goal of this stage is to protect user identity information. If you want to save costs and do not need this function, you can omit the part of this stage that uses the covert channel to embed information, and still use the normal authentication process. This system supports the flexible use of various functions and modules.

[0048] (2) Client-server authentication phase: This phase is used to implement authentication between the client and the server. After receiving the authentication request, the server verifies the client's identity information and checks whether the client is registered. If the client is not registered, the authentication fails for an illegal user. If the identity information is valid, the authentication succeeds. Then the server uses the key transmission module to generate a fake communication information FKI. A , such as false keys, false mission information, etc., transmitted in public channels to mislead or even induce attackers to conduct reverse attacks. At the same time, the real key parameter RP must be generated A Then, according to the encoding splitting rule KDR received from the client, the real key parameter RP A Split it to get RP1 and RP2. KDR rules can be various, such as: split in half, odd-even split, etc., or specify how many bits in a piece of data are the real key parameters. The rule KDR can use a small number of bits to indicate the true position of the key parameters. Then RP1 is transmitted in the open channel, and RP2 is transmitted in the covert channel. This is equivalent to transmitting key information on two paths. The attacker needs to obtain all the key information of the two channels, and then obtain the correct rules to reassemble, splice and decode to obtain the real key RP. A .

[0049] Further expansion, corresponding to the expansion part of the previous stage, after the identity authentication is successful, the key parameters will be returned from the channel from which the real identity information is verified (or it will be returned from another channel accordingly), and it is no longer specified which channel transmits which messages and the key parameters are no longer split. The sender of the previous stage is also the receiver of this stage, so it is easy to know which channel transmits the real information and directly decode the key parameters, and use the tacit understanding of the successfully verified identity to reduce the cost of calculation and judgment. At the same time, the randomness of channel transmission and the difficulty of cracking the key are increased, because even if the attacker obtains the information of the two channels, he cannot distinguish which channel's key parameters are real, which can enhance the security of key transmission. At this time, the complex unprotected rules KDR will no longer be transmitted, reducing the amount of unprotected data transmitted in the channel. Similarly, for this method and system, the goal of this stage is to protect key transmission. If you want to save overhead, you can omit the functions in this stage and directly transmit the key in the public channel.

[0050] (3) Key exchange phase: After receiving the key parameters RP1 and RP2, the client's hidden information extraction module decodes and extracts information from the two channels, and decodes and recovers the key according to the KDR rule to obtain the key SK for the next communication session. i Next, for SK i This important information is also encoded and split according to the rule KDR to obtain two parts SK i,1 and SK i,2 . Then SK i,1 Transmitted in an open channel, while SK i,2 The hidden information embedding module is used to transmit in the covert channel. Finally, at this stage, the key transmission module of the client needs to generate a key replacement rule KR. In the subsequent communication process, when both parties determine that the conditions specified by the KR are met, the two parties will use the covert channel to negotiate and replace the key. Irregular key replacement can enhance the security and reliability of communication, and the process of replacing the key using the covert channel is not easy to be discovered by attackers. At the same time, the KR replacement conditions can be varied, such as starting to replace the key when important information needs to be transmitted or when a certain amount of data has been transmitted.

[0051] Further expansion, corresponding to the expansion part of the previous stage, does not perform the splitting rules for transmission, the key SK i In one of the channels, for example, the key is returned by the channel that received the real and correct parameter information last time (or returned from another channel), and the sender of the previous stage is also the receiver of this stage, so it is easy to know which channel transmits the real information and directly decode the key. Similarly, for this method and system, the goal of this stage is to protect the key transmission. If you want to save overhead, you can omit the functions in this stage and directly transmit the key in the public channel.

[0052] (4) Encrypted communication phase: After the server receives all the information, it converts SK into i,1 and SK i,2 Restore the key SK for communication i , or the corresponding extension receives all the keys directly from one of the channels. Then the server and client will send SK i As the session key of communication, the data is encrypted and transmitted in the public channel. Finally, in this stage, the continuous verification module needs to generate a short tag DRL as a subsequent lightweight authentication identifier.

[0053] (5) Continuous verification stage: After the client receives the short tag DRL, it embeds it into the covert channel and transmits it simultaneously with the data of the public channel. At this time, if an attacker attempts to join the communication process to perform a man-in-the-middle attack, a forgery attack, etc., since its covert channel does not contain the short tag DRL, it will be detected and warned by the continuous verification module when it establishes a communication connection with the client and the server. In this way, the data security of the entire communication process can be guaranteed at a relatively low cost. Similarly, for the present method and system, the goal of this stage is to continuously authenticate and identify to ensure the security of the entire communication process. If you want to save costs, you can omit the functions in this stage and do not embed short tag identification and authentication in the covert channel.

[0054] The following introduces a covert channel method based on the delay sequence between data packets.

[0055] First of all, it should be emphasized that a variety of technologies for establishing covert channels can be applied to the above-mentioned identity authentication process. They are not limited to a certain covert channel information embedding method. They can be embedded in combination with multiple methods to establish a covert channel to embed hidden information, and can be flexibly deployed in the covert information embedding module and the covert information extraction module according to different scenarios and overheads. This patent proposes a method for establishing a covert channel based on the delay sequence between data packets, which does not mean that the above-mentioned identity authentication process must adopt this method to establish a covert channel in order to work. The detailed working principle is introduced below.

[0056] D={D0,D1,…,D k ,…,D m} (1)

[0057] IPD={IPD0,IPD1,…,IPD i ,…,IPD j} (2)

[0058]

[0059] IPD'={IPD1',IPD'2,...,IPD' k ,...,IPD' m} (4)

[0060]

[0061] By adjusting the delay sequence between data packets, a covert channel is established to embed information and transmit data. The specific workflow is as follows: first, the embedded information stream is converted into a binary codeword D as shown in formula (1), and the data packet delay interval sequence IPD is recorded as shown in formula (2). After encoding, IPD coded The sequence is shown in formula (3). Finally, the sender sends the data packet according to this time sequence. The receiver records the arrival time of the data packet and calculates the inter-data packet delay sequence IPD' as shown in formula (4). Then, the codeword is obtained according to the decoding rule. Ddecode The original embedded information is restored as shown in formula (5). The basic principle of the algorithm proposed in this patent is to divide the IPD into multiple groups, each of which embeds 1 bit of information, i.e., 1 codeword D k There are many coding grouping methods to choose from. The following will give examples to explain various grouping coding methods in detail, and subdivide them into two parts: concealed channel coding module and decoding module for introduction.

[0062] (1) Method 1

[0063] ① Encoding module: This method converts the IPD sequence {IPD0, IPD1, ..., IPD i ,…,IPD j} are divided into groups of two to obtain {IPD0, IPD1,…, IPD 2k ,IPD 2k+1 ,…,IPD j}, each sequence {IPD 2k ,IPD 2k+1} Based on adjusting the order of elements without changing the order of sending packets, embed a codeword D k , before that, first increase the distance between each two IPDs according to formula (6), which can better improve the algorithm's anti-delay jitter performance. When the distance between adjacent IPDs is less than a, increase the larger IPD by Δ. Then adjust the delay sequence between data packets according to formula (7) for encoding operations. If the embedded information is 0, compare the IPD 2k and IPD 2k+1 Size, if IPD 2k >IPD 2k+1 The encoded IPD coded The sequence order remains unchanged, if IPD 2k <IPD 2k+1 Then swap the order of the two elements; if the embedded information is 1, compare the IPD 2k and IPD 2k+1 Size, if IPD 2k <IPD2k+1 The encoded IPD coded The sequence order remains unchanged, if IPD 2k >IPD 2k+1 Then swap the order of the two elements. Continuously encode all codewords D to obtain IPD coded sequence, and finally the sender sends the data packet according to IPD coded The interval time of the sequence is sent out.

[0064]

[0065] ②Decoding module: record the time when the data packet arrives to get the sequence IPD'. Compare the size of two adjacent IPD's. If IPD' 2k-1 >IPD' 2k , then D k decode =0, if IPD' 2k-1 <IPD' 2k , then D k decode =1, decode according to formula (8) (9) to get codeword D decode .

[0066] IPD'={IPD1',IPD'2,...,IPD' k ,...,IPD' m} (8)

[0067]

[0068] (2) Method 2

[0069] ① Encoding module: This method converts the IPD sequence {IPD0, IPD1, ..., IPD i ,…,IPD j} is divided into groups of three to obtain {IPD0, IPD1, IPD2,…, IPD 3k ,IPD 3k+1 ,IPD 3k+2 ,…,IPD j}, each sequence {IPD 3k ,IPD 3k+1 ,IPD 3k+2}Embed a codeword D based on adjusting the order of elements k , before that, sort each group of three elements in descending order to get {IPD max ,IPD middle ,IPD min}, then increase the distance between IPDs according to formula (10), and also take the approach of giving IPD maxThe operation of increasing Δ increases the distance between the maximum and minimum values ​​in a group, thereby improving the algorithm's anti-delay jitter performance. Then adjust the delay order between data packets according to formula (11) for encoding operations. If the embedded information is 0, the order of elements is swapped to make it {IPD max ,IPD min ,IPD middle}; If the embedding information is 1, the order of elements is swapped to make it {IPD min ,IPD max ,IPD middle}. It is worth noting that IPD max and IPD min Placing them at adjacent positions can make full use of their distance to resist jitter. If the network status is good, the operation of formula (8) can be omitted, saving the overhead of encoding embedding. Continuously encode all codewords D to obtain the IPD sequence, and finally the sender sends the data packet according to the IPD sequence. coded The interval time of the sequence is sent out.

[0070]

[0071] ②Decoding module: record the arrival time of the data packet to get the sequence IPD', divide the IPD' sequence into three groups. Compare the size of each group of IPD'. If IPD3' k >IPD3' k+2 ,but If IPD3' k <IPD3' k+2 ,but According to formula (12), the code word D is obtained by decoding decode .

[0072]

[0073] (3) Method 3

[0074] ① Encoding module: This method converts the IPD sequence {IPD0, IPD1, ..., IPD i ,…,IPD j} is also divided into groups of three to obtain {IPD0, IPD1, IPD2,…, IPD 3k ,IPD 3k+1 ,IPD 3k+2 ,…,IPD j}, each sequence {IPD 3k ,IPD 3k+1 ,IPD 3k+2}Embed a codeword D based on adjusting the order of elements k , before that, sort each group of three elements in descending order to get {IPD max,IPD middle ,IPD min}, then increase the distance between adjacent IPDs according to formula (13), and also take the approach of giving IPD max The operation of increasing Δ increases the distance between the maximum and minimum values ​​in a group, thereby improving the algorithm's anti-delay jitter performance. Then adjust the delay order between data packets according to formula (14) for encoding. If the embedded information is 100, the order of elements is swapped to make it {IPD max ,IPD middle ,IPD min}; If the embedded information is 001, swap the order of elements to make it {IPD min ,IPD middle ,IPD max}; If the embedded information is 010, swap the order of elements to make it {IPD min ,IPD max ,IPD middle}. Continuously encode all codewords D to obtain the IPD sequence, and finally the sender sends the data packet according to the IPD coded The interval time of the sequence is sent out.

[0075]

[0076] ②Decoding module: record the arrival time of the data packet to get the sequence IPD', divide the IPD' sequence into three groups. Compare the size of each group of IPD'. If IPD3' k >IPD3' k+1 >IPD3' k+2 ,but If IPD3' k <IPD3' k+1 <IPD3' k+2 ,but If IPD3' k <IPD3' k+1 And IPD3' k+1 >IPD3' k+2 ,but According to formula (15), the code word D is obtained by decoding decode .

[0077]

[0078] The corresponding method of the embedded information in method 3 is not fixed. The set of embedded information in formula (14) is {100,010,001}. The user can also select the encoding set as {110,011,001}, encode it according to formula (16), and finally decode it according to the IPD sequence size at the receiving end.

[0079]

[0080] The difference between method 2 and method 3 is that method 2 encodes 1 bit with 3 IPD delays, while method 3 encodes 3 bits with 3 IPD delays. The coding efficiency is different, so the number of data packets required for the data stream is also different. It can be extended to encode in groups of n, and there are also two corresponding encoding methods, which will be introduced in detail below.

[0081] (4) Method 4

[0082] ① Encoding module: This method converts the IPD sequence {IPD0, IPD1, ..., IPD i ,…,IPD j} is divided into groups of n to obtain {IPD0, IPD1,…, IPD n-1 ,…,IPD nk ,IPD nk+1 ,…,IPD n(k+1)-1 ,…,IPD j}, each sequence {IPD nk ,IPD nk+1 ,…,IPD n(k+1)-1}Embed a codeword D based on adjusting the order of elements k Before that, sort each group of n elements in descending order to obtain {IPD1, IPD2, …, IPD n}. It is worth pointing out that, obviously, as the number of groups increases, the distance between the maximum IPD and the minimum IPD will theoretically increase first. Therefore, under certain circumstances, the larger n is, the better the anti-jitter performance is. However, this may not increase infinitely but remain within a certain range. Therefore, the larger the number of groups n is, the better. The larger n is, the lower the coding efficiency will be, and the coding overhead will increase. After grouping, the distance between IPDs is still increased according to formula (17). The method of increasing the distance between the maximum and minimum values ​​in a group is also adopted to increase the algorithm's anti-delay jitter performance. Then, the delay order between data packets is adjusted according to formula (18) for encoding operations. If the embedded information is 0, the order of elements is swapped to make it {IPD1, IPD n ,…,IPD n-1 ,IPD2}; if the embedding information is 1, the order of elements is swapped to make it {IPD n ,IPD1,…,IPD n-1 ,IPD2}.

[0083]

[0084] It is worth noting that IPD1 and IPD nPlacing them in adjacent positions can make full use of their distance to resist jitter. If the network status is poor, in order to save coding overhead, they can be divided into groups of two when exchanging the order of elements. According to the watermark information embedding, if the embedded information is 0, the order of elements is exchanged to make it as formula (19); if the embedded information is 1, the order of elements is exchanged to make it as formula (20). Continuously encode all codewords D to obtain the IPD sequence, and finally the sender sends the data packet according to the IPD coded The interval time of the sequence is sent out.

[0085]

[0086] ②Decoding module: Get the sequence IPD' according to the arrival time of the recorded data packets, and divide the IPD' sequence into n groups. Compare the size of each group of IPD'. If IPD1'>IPD n ',but If IPD1' <IPD n ',but According to formula (21), the code word D is obtained by decoding decode .

[0087]

[0088] In addition, the decoding method corresponding to the encoding method of formula (19) and (20) is formula (21). The n IPD' sequences are compared in groups of two. If the former is larger than the latter in most cases, then If the majority is that the former is smaller than the latter, then According to formula (22), the code word D is obtained by sequential decoding decode .

[0089] In summary, mode 4 is the promotion and application of mode 1 and mode 2. If n=2, it is equivalent to mode 1 encoding and decoding, and the coding set is {0,1}; if n=3, it is equivalent to mode 2 encoding and decoding, and the coding set is also {0,1}.

[0090]

[0091] (5) Method 5

[0092] Codec module: This method converts the IPD sequence {IPD0, IPD1, ..., IPD i ,…,IPD j} is divided into groups of n to obtain {IPD0, IPD1,…, IPD n-1 ,…,IPD nk ,IPD nk+1 ,…,IPD n(k+1)-1 ,…,IPD j}, each sequence {IPD nk ,IPDnk+1 ,…,IPD n(k+1)-1}Embed codeword D based on adjusting the order of elements k Before that, sort each group of n elements in descending order to obtain {IPD1, IPD2, …, IPD n Method 5 is the promotion and application of the above method. If n=3, it is equivalent to the encoding and decoding of method 3. The encoding set is determined by the user as {100,010,001} or {011,101,110}, etc. The number of encoding elements is For every n groups, you need to first determine the coding set, and then adjust the sequence coding information to perform the coding operation. For example, n = 5, the number of codes is The coding set can be {10000, 01000, 00100, 00010, 00001}, where "1" is the position of the largest IPD in each group, or the coding set is {01111, 10111, 11011, 11101, 11110}, where "0" is the position of the smallest IPD in each group. The decoding also compares the element size and then decodes according to the provisions of the encoding, which will not be repeated here; if n = 5 and the number of codes is Then the coding set can be {11000,10100,10010,10001,01100,01010,01001,00110,00101,00011}, where the first "1" is the position of the largest IPD in each group, and the second "1" is the position of the second largest IPD in each group. The coding set can also be {00111,01011,01101,01110,10011,10101,10110,11001,11010,11100}, where the first "0" is the position of the smallest IPD in each group, and the second "0" is the position of the second smallest IPD in each group. It can also be seen that the decoding compares the element size according to the regulations during encoding, which will not be repeated here.

[0093] The following examples are used to introduce application scenarios of the present invention.

[0094] With the development of smart city construction and low-altitude economy, drones will play an indispensable and important role in it, so the security identity authentication of drones becomes particularly important. The present invention can be applied to the identity authentication of drones and ground stations, such as Figure 3 As shown. The smart city is divided into multiple task execution areas. Multiple drones can be deployed in one task execution area. The ground station is responsible for communicating with all drones as the control center and data center, and the server is responsible for storing all necessary data. Among them, the ground station authenticates each legal drone scenario applicable to this patent. The drone can be used as the client of the present invention, and the ground station can be used as the server of the present invention for identity authentication.

[0095] Existing computer networks all use explicit channels for communication. Even if encryption is used, their openness makes both parties in communication vulnerable to attacks. Especially in P2P networks, attackers may eavesdrop and intercept user identities, and then use forged hijacked information to communicate with the target. Deploy the patented identity authentication mechanism on the sender and receiver of the FTP platform, introduce covert channels to embed important authentication information to protect the privacy of user identity information, and at the same time prevent attackers from eavesdropping, provide highly reliable identity authentication, and use the patented short tag continuous authentication method to provide security protection for the entire communication process, such as Figure 4 shown.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An identity authentication method based on a covert channel, characterized in that: The following steps are involved: Step 1: Split or confuse the user identity information used for verification in the covert channel and the public channel for transmission, and generate misleading forged identity information for transmission in the two channels; Step 2: Splitting the key, and transmitting the split parts of the key in the covert channel and the public channel respectively; Step 3: During the encrypted communication phase, short tag information is embedded in the covert channel to continuously authenticate the client.

2. The identity authentication method based on covert channel as claimed in claim 1, characterized in that: It also includes performing step 2 to renegotiate and replace the key, and then performing step 3.

3. The identity authentication method based on covert channel as claimed in claim 1, characterized in that: The step 2 includes constructing a covert channel method based on the delay sequence between data packets, including the following steps: Convert the embedded information stream into binary codewords, record the delay interval sequence of the data packet, and obtain the time sequence after encoding. The sending end then sends the data packet according to the time sequence. The receiving end records the arrival time of the data packets and calculates the delay sequence between data packets, and then obtains the codeword according to the decoding rules to restore the original embedded information.

4. The identity authentication method based on covert channel as claimed in claim 3, characterized in that: The method also includes grouping and encoding the data packet delay interval sequence, wherein each group is embedded with 1 bit of information, ie, 1 code word.

5. A covert channel-based identity authentication device, characterized in that: It includes an identity authentication client and an identity authentication server, wherein a covert channel and an open channel are constructed between the identity authentication client and the identity authentication server; The covert channel and the public channel transmit user identity information for verification, which is misleading and forged identity information; Used to transmit the split keys separately; The covert channel is also used to transmit short tag information for continuous authentication.

6. The covert channel-based identity authentication device according to claim 5, characterized in that: The identity authentication client and the identity authentication server both include: an identity information hiding module, a key transmission module, a continuous verification module, a hidden information embedding module, and a hidden information extraction module; The identity information hiding module, key transmission module, and continuous verification module are responsible for generating the required corresponding information, determining the corresponding information to be transmitted in the channel, and the next task execution plan after receiving the information; the hidden information embedding module and hidden information extraction module are used to embed information into the hidden channel or extract it from it; The identity information hiding module is used to generate false identity information and false key parameter information, and to generate a rule for encoding or splitting the key.

7. The covert channel-based identity authentication device according to claim 6, characterized in that: The identity authentication client and the identity authentication server perform the following collaborative work to complete the identity authentication; Initialization phase: The client establishes a communication connection with the server, sends an identity authentication request to the server, uses the hidden information embedding module to transmit the user identity information to be used for verification in the covert channel, and transmits the identity information and fake key parameter information forged by the identity information hiding module in the public channel; the public channel and the covert channel are allowed to randomly select the transmission of true and false identity information, and the server only needs to verify a complete real identity information; Authentication stage: used to implement identity authentication between the client and the server. After receiving the authentication request, the server verifies the identity information of the client and checks whether the client is registered. If not, the authentication fails if the client is an illegal user. If the identity information is valid, the authentication succeeds. Then the server uses the key transmission module to generate fake communication information and the real key parameters. Then, according to the encoding splitting rules received from the client, the real key parameters are split to obtain two split key parameters for transmission. Key exchange stage: after receiving the two split key parameters from the two channels, the client decodes and recovers the key according to the encoding splitting rule to obtain the communication session key used for the next communication session; the above communication session key is split according to the encoding splitting rule to obtain two split communication session keys, which are transmitted in the public channel and the covert channel respectively; Encrypted communication stage: After the server receives all the information, it will restore and splice the two split communication session keys into a communication key according to the encoding splitting rule; then the server and the client will use the communication key as the communication session key to encrypt and transmit data in a public channel.

8. The covert channel-based identity authentication device according to claim 7, characterized in that: During the encrypted communication phase, a short tag is generated by the continuous verification module as a subsequent lightweight authentication identifier, and then the continuous verification phase is entered. After receiving the short tag, the client embeds it into the covert channel and transmits the data of the public channel simultaneously; at this time, if an attacker attempts to join the communication process to perform a man-in-the-middle attack, forgery attack, etc., since its covert channel does not contain the short tag, it will be detected and warned by the continuous verification module when it establishes a communication connection with the client and the server.

9. The covert channel-based identity authentication device according to claim 5, characterized in that: The information transmission path is changed so that the public channel is used to transmit the user identity information to be used for verification, and the covert channel is used to transmit misleading forged identity information.

10. Application of the identity authentication device according to any one of claims 5 to 9, characterized in that: Including the application of drone identification and FTP platform.

Images