Group communication method and system based on hierarchical asymmetric key pool

Abstract

In the group communication system based on the asymmetric key pool of this patent, the status of all members who have the group key pool is divided into levels, and the protection measures and key pools of different levels are different. The key pool is calculated by the key pool of important level members based on the chip key, replacement parameters, etc., and once its security chip finds itself as an untrusted node, it will no longer conduct subsequent group communications. Therefore, even if it is captured, the impact is not significant and will not cause the failure of the entire group communication system. This patent combines the asymmetric key pool and the chip key. In the scenario of group communication, it further enhances the security of the use of the asymmetric key pool, so that in the extreme case where the asymmetric key pool is cracked, the security of group communication based on the asymmetric key pool can still be guaranteed. The key pool update method can update the key pool without transmitting the update key. The key transmission amount of the key update scheme of this patent is very small and easy to implement.

Description

Technical Field

[0001] The present invention relates to the field of quantum-resistant computing, and in particular to a group communication method and system based on a hierarchical asymmetric key pool. Background Art

[0002] With the continuous development of wireless communication technology, direct communication between terminals (Device to Device, D2D) has become one of the hot spots of 3GPP Rel-12 standardized technology. D2D allows two user equipment (User Equipment, UE) to directly transmit data through a specific channel (Sidelink Channel) without going through an evolved base station device (Evolutional Node B, eNB). Of course, D2D is not limited to data transmission between two user equipments, but can also support point-to-multipoint group communication (Group Communication). Most of the existing network authentication systems are based on a one-to-one authentication method for a single object, but for point-to-multipoint data transmission, a group will be formed according to certain principles. In these application scenarios, when a new terminal is connected to the group, if the existing one-to-one authentication method is used, it will not only increase network signaling, causing network congestion, but also occupy a large amount of network resources. Therefore, the existing one-to-one network authentication system is no longer applicable. In this case, in order to reduce the consumption of authentication resources and reduce network congestion, a corresponding group authentication mechanism is required. Existing group communication systems use a group key pool to implement group communication by using symmetric keys stored in a group symmetric key pool. If a member is attacked, the confidentiality of the entire group's communication is threatened.

[0003] In the prior art, updating the key pool often requires the participation of the issuing center, which poses a certain threat to security due to the large amount of data transmitted.

[0004] Based on the above analysis, the prior art has the following defects:

[0005] 1. In the prior art, group communication is usually protected by a symmetric key pool. Due to its large capacity, the symmetric key pool cannot be stored in a highly secure security chip, and there is a possibility that it will be captured, disassembled, and cracked. The group symmetric key pool is shared by all members of the group. Once the group symmetric key pool is cracked, the security of group communication based on the group symmetric key pool is threatened;

[0006] 2. The existing key pool update method is that one party generates a key and then sends it to the other party. Since the key pool has a huge amount of keys, it takes a lot of time to update the key pool. For group communication, the same key needs to be transmitted to each member of the group. The amount of keys is even larger, which is often difficult to achieve.

[0007] 3. In the existing group communication system based on the key pool, the status of all members who have the group key pool is the same, and the capture of any member will lead to the failure of the entire group communication system. Summary of the invention

[0008] In view of the problems in the related art, the present invention proposes a group communication method and system based on a hierarchical asymmetric key pool to overcome the above technical problems existing in the existing related art.

[0009] To this end, the specific technical solution adopted by the present invention is as follows:

[0010] A group communication method based on a hierarchical asymmetric key pool, wherein nodes in a group are divided into multiple levels according to permissions, each group node has an identity list of the current group, each identity information contains the level number of the node, the administrator is the highest level, the group node security chip stores the chip key, replacement parameters and administrator public key of the current level, the administrator security chip also stores the lowest level chip key, the chip key, replacement parameters and administrator public and private keys of the current level; the memory outside the security chip of the common node and the administrator node stores the asymmetric key pool of the current level; the chip key and the asymmetric key pool are updated using the replacement parameters during the communication process, including the following steps:

[0011] (1) If the group nodes of the same layer communicate, the communicating parties select an asymmetric key from the non-key pool of the current layer and a chip key of the current layer according to a preset asymmetric key selection method, calculate a communication key based on the Diffie-Hellman key exchange protocol, and calculate a first session key based on the communication key;

[0012] (2) If group nodes at different layers communicate with each other, the group node at the higher layer selects an asymmetric key from the key pool of the current layer as the private key of the current layer according to a pre-set asymmetric key selection method, uses the chip key of the current layer as the public key of the lower layer, calculates a communication key based on the private key of the current layer and the public key of the lower layer based on the Diffie-Hellman key exchange protocol, and calculates a first session key based on the communication key;

[0013] (3) The lower-layer group node selects an asymmetric key from the key pool of the current layer as the public key of the upper layer according to a pre-set asymmetric key selection method, and uses the chip key of the current layer as the private key of the current layer; the communication key is calculated based on the Diffie-Hellman key exchange protocol using the private key of the upper layer and the public key of the current layer, and the first session key that is the same as that of the upper-layer group node is calculated using the communication key;

[0014] (4) The group nodes communicate using the first session key.

[0015] Preferably, the updating of the chip key using the replacement parameter comprises the following steps: transforming the chip key of the next level into the chip key of the previous level through the Diffie-Hellman key exchange protocol; the administrator generates a new replacement parameter to update the chip key;

[0016] Optionally, the use of replacement parameters to update the asymmetric key pool includes the following steps: the administrator layer key pool is initialized to a key pool composed of true random numbers, the key pool of this layer is divided into multiple segments of sub-keys, and each segment of sub-key is calculated by the Diffie-Hellman key exchange protocol to obtain the segment sub-key of the next layer; then the multiple calculation results are spliced ​​in the order of corresponding sub-keys to obtain the key pool of the next layer; the administrator generates new replacement parameters to update the multiple segments of sub-keys, and the multiple calculation results after the update are spliced ​​in the order of corresponding sub-keys to obtain an updated key pool.

[0017] When the group communication node sends a notification, the layer-by-layer communication method comprises the following steps: the group administrator obtains the second session key according to the method described in step (2), uses the private key to sign the first message containing the notification, the replacement parameter, and the current timestamp to obtain the signature information, encrypts the second message containing the notification, the replacement parameter and the signature information by the second session key to obtain the third message and calculates the first message verification code, combines the administrator identity information, the current timestamp, the third message and the first message verification code to obtain the first encrypted message and sends it to the lower-layer node, uses the replacement parameter to update the asymmetric key pool, and records the replacement parameter CR used this time into the security chip;

[0018] After receiving the message, the trusted node obtains the second session key according to the method described in step (3), uses the second session key to decrypt the first encrypted message, and uses the administrator public key stored in the local security chip to verify the signature information;

[0019] If the trusted node has no subordinate nodes, the replacement parameter is used to update the asymmetric key pool, and the replacement parameter CR used this time is recorded in the security chip;

[0020] If the trusted node has a subordinate node, the trusted node transmits the combination of the first message and the signature information to the subordinate node. The trusted node obtains the third session key according to the method described in step (2), encrypts the second message with the third session key to obtain the fourth message, calculates the second message verification code, combines the trusted node identity information, the current timestamp, the fourth message and the second message verification code to obtain the second encrypted message and sends it to the subordinate node. The replacement parameter is used to update the asymmetric key pool and the chip key, and the replacement parameter CR used this time is recorded in the security chip;

[0021] After receiving the second encrypted message, the lower-level node obtains the third session key according to the method described in step (3), uses the third session key to decrypt the second encrypted message, and verifies the signature using the administrator public key stored in the local security chip;

[0022] When a node is untrustworthy, the illegal information of the untrustworthy node is notified to nodes at each layer layer by layer.

[0023] When a new trusted node is added, the administrator assigns the chip key and asymmetric key pool of the current node in the group to the trusted node according to the layer number of the new trusted node, and notifies the nodes at each layer layer by layer. The notification is a legitimate message of the new trusted node, and the parties do not replace the key in this communication process.

[0024] A group communication system based on a hierarchical asymmetric key pool, used to implement the above-mentioned group communication method based on a hierarchical asymmetric key pool, characterized in that the system includes an administrator and a group node, the administrator and the group node communicate according to the above-mentioned method, the administrator and the group node are both equipped with a security chip with anti-disassembly function, and the administrator is the highest level and has the ability to issue key cards.

[0025] The beneficial effects of the invention are:

[0026] Beneficial effects:

[0027] 1. This patent combines the asymmetric key pool and the chip key, and further enhances the security of the asymmetric key pool in the group communication scenario, so that in the extreme case that the asymmetric key pool is cracked, the security of the group communication based on the asymmetric key pool can still be guaranteed. Because the keys of both parties are also protected by the chip key, if the chip key can be guaranteed not to be cracked, the communication between the two parties will not be cracked due to the cracking of the asymmetric key pool;

[0028] 2. The patented key pool updating method can update the key pool without transmitting the update key. Since the calculation amount of the update key is small, the key pool update takes less time. For group communication, the key transmission amount of the patented key update scheme is very small and easy to implement.

[0029] 3. In the group communication system based on the asymmetric key pool of this patent, the status of all members who have the group key pool is divided into levels, and the protection measures and key pools of different levels are different. The protection measures of important level members are good and not easy to be captured; the protection measures of unimportant level members are relatively poor or the working environment is more unsafe, but because their key pool is calculated based on the chip key, replacement parameters and the key pool of important level members, even if the enemy obtains the key pool, it cannot deduce the key pool of other nodes without the chip key and replacement parameters, and once its security chip finds itself as an untrusted node, it will no longer conduct subsequent group communications, so even if it is captured, it will not have much impact and will not cause the failure of the entire group communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 is a system structure diagram involved in an embodiment of the present invention;

[0032] Figure 2 This is the calculation process of the key pools at each layer and the chip keys at each layer in the embodiment of the present invention. DETAILED DESCRIPTION

[0033] To further illustrate each embodiment, the present invention provides drawings, which are part of the disclosure of the present invention and are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, ordinary technicians in the field should be able to understand other possible implementations and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0034] It should be understood that, where technically feasible, the technical features listed above for different embodiments can be combined with each other to form other embodiments within the scope of the present invention. In addition, the specific examples and embodiments described in the present invention are non-limiting, and the structures, steps, and sequences described above can be modified accordingly without departing from the scope of protection of the present invention.

[0035] In a communication group, this patent assumes that all members have a list of IDs of the current group, and each ID contains the layer number of the ID. The smaller the layer number, the better the security protection measures and the lower the possibility of being captured by the enemy.

[0036] like Figure 1 As shown, the group communication system based on the hierarchical asymmetric key pool of the present invention includes multiple layers of nodes such as layer 0 nodes, layer 1 nodes, and layer 2 nodes. In the military data link scenario, the layer 0 node can be a command center, the layer 1 node can be a command machine, and the layer 2 node can be a drone, an unmanned vehicle, or a single soldier node.

[0037] In this patent, each layer of nodes is equipped with a security chip, which has anti-disassembly function, and the enemy cannot obtain the content stored in the security chip. Since the 0th layer node is the group administrator and has the ability to issue key cards, its security chip also stores the lowest level chip key (i.e. the 2nd layer chip key KR in this patent). 2 ) is used to issue chip keys of the corresponding layer to newly added group members. The asymmetric key pool of the administrator node is stored in a memory outside the security chip. The security chip of the administrator node stores chip keys, replacement parameters, and the administrator's public and private keys; the asymmetric key pool of other ordinary group members is stored in a memory outside the security chip. The node's security chip stores chip keys, replacement parameters, and the administrator's public key.

[0038] The security chip of each layer stores the chip key KR and replacement parameter CR of the layer. The process of using the replacement parameter to transform the chip key is as follows: Figure 2 As shown, the text description is as follows:

[0039] Assume the chip key of layer 0 is KR 0 , and so on, the first layer chip key is KR 1 , the second layer chip key is KR 2 .

[0040] According to the Diffie-Hellman protocol, a large prime number p and the primitive root g of p are defined. Both g and p are parameters of the Diffie-Hellman protocol. The DH public key PK can be calculated through the DH private key SK, that is, PK = g SK mod p. The administrator node selects a true random large integer KR for the lowest level node, i.e., the second level node in this patent. 2 As the second layer chip key, through KR 2 Calculated By KR 1 Calculated KR 1 For KR 2 The public key, KR 0 For KR 1 The public key of

[0041] When a key replacement is performed, the group administrator generates a new replacement parameter CR for KR2 Transform to get KR' 2 =KR 2 *CR. vs. KR 1 Transform to get Similarly,

[0042] In this patent, each node also stores an asymmetric key pool based on a hierarchical structure. The process of transforming the asymmetric key pool using replacement parameters is as follows: Figure 2 As shown, the text description is as follows:

[0043] The 0th layer key pool is initialized as a key pool composed of true random numbers. The 0th layer key pool is evenly divided into multiple segments of keys, and the i-th segment is K0 i Similarly, the i-th segment of the first-layer key pool and the second-layer key pool is K1 i , K2 i .

[0044] By K0 i Calculated K1 i K0 i Calculate the public key of each K1 i The first layer key pool is obtained by combining them.

[0045] By K1 i Calculated K2 i K1 i Calculate the public key of each K2 i The second layer key pool is obtained by combining them.

[0046] When a key replacement is performed, the group administrator generates a new replacement parameter CR for K0 i Transform to get K0' i =K0 i *CR. for K1 i Transform to get Similarly,

[0047] To further illustrate the principle of the present invention, the implementation principle of the present invention is described in detail below through specific implementation methods.

[0048] Example 1: Group communication when members are trusted

[0049] Case 1.1: Communicating with peer group members.

[0050] Assume that the message to be sent by group member A is NTF, and a timestamp TNTF is generated for the message.

[0051] A calculates the pointer Pos = F P (TNTF), function F P (*) is an arbitrarily specified function that transforms TNTF into a legal pointer. According to Pos, the key K is taken out from the asymmetric key pool. Pos .

[0052] Calculate the communication key K TG =K Pos *g KR mpd p, KR is the chip key of the current layer.

[0053] Calculate the session key K SG =MAC(TNTF,K TG ). MAC is a session key generation function, such as a message authentication code function.

[0054] A uses the session key K SG As the group key for this group communication, NTF is symmetrically encrypted to obtain {NTF}K SG , using K SG ID A , TNTF and NTF calculate the message authentication code to get MAC (ID A ||TNTF||NTF,K SG ). The encrypted information, message authentication code and ID A , TNTF to other members, the information sent can be represented by ID A ||TNTF||{NTF}K SG ||MAC(ID A ||TNTF||NTF,K SG ).

[0055] After receiving it, other members of the same layer use the same method to take out K Pos , combined with the chip key KR and TNTF of this layer, calculate K SG , using K SG Decrypt {NTF}K SG Get the message NTF, use K SG ID A , TNTF and NTF calculate the message authentication code and compare it with the received message authentication code. If the two are consistent, it means that the verification is successful. After the verification is successful, the message NTF is trusted; if the verification fails, the message NTF is not trusted.

[0056] Case 1.2: A communicates with subordinate group member B.

[0057] Assume that the message to be sent by group member A is NTF, and a timestamp TNTF is generated for the message.

[0058] The parent A calculates the pointer Pos = F PK (TNTF), function F PK (*) is an arbitrarily specified function that transforms TNTF into a legal pointer. According to Pos, the key K is taken out from the asymmetric key pool. A As the private key of the upper layer, the chip key KR A As the subordinate's public key.

[0059] A calculates the communication key

[0060] A calculates the session key K SGA =MAC(TNTF,K TGA ).

[0061] A uses K SGA Protect the message sent to B, that is, encrypt and authenticate the message.

[0062] After receiving it, B calculates the pointer Pos = F PK (TNTF), take out the key K from the asymmetric key pool according to Pos B As the public key of the upper layer, the chip key KR B As the subordinate's private key.

[0063] B calculates the communication key

[0064] because so

[0065] B calculation and K SGA The same session key K SGB =MAC(TNTF,K TGB ), B uses K SGB Decrypt the received message and complete message authentication.

[0066] Case 1.3: B communicates with A, a member of the upper group.

[0067] Assume that the message to be sent by group member B is NTF, and a timestamp TNTF is generated for the message.

[0068] B calculates the pointer Pos = F PK (TNTF), take out the key K from the asymmetric key pool according to Pos B As the public key of the upper layer, the chip key KR B As the subordinate's private key.

[0069] B calculates the communication key

[0070] B calculates the session key K SGB =MAC(TNTF,K TGB ).

[0071] B uses K SGB Protect the message sent to A, that is, encrypt and authenticate the message.

[0072] After receiving it, the superior A calculates the pointer Pos = F PK (TNTF), take out the key K from the asymmetric key pool according to Pos A As the private key of the upper layer, the chip key KR A As the subordinate's public key.

[0073] A calculates the communication key According to the description in situation 1.2, K TGA =K TGB .

[0074] A calculation and K SGB The same session key K SGA =MAC(TNTF,K TGA ), A uses K SGA Decrypt the received message and complete message authentication.

[0075] Example 2: Group communication when one member is untrustworthy

[0076] Case 2.1: The untrusted member is layer 1 node X.

[0077] Assume that the group administrator is the 0th layer node A, a trusted member in the group is the 1st layer node B, and the untrusted member is the 1st layer node X. For example, X is captured or defected. Since X knows the key pool of this layer and all lower layers, the security of group communication of this layer and all lower layers is affected. According to K1 i Get K0 i This is a discrete logarithm problem, so if X does not have a quantum computer, it is impossible to solve it according to K1. i Get K0 i That is, the upper key pool is safe at this time.

[0078] Step 1: The group administrator sends a message.

[0079] A generates a message NTF to declare X illegal, and generates a timestamp TNTF for the message. A generates a replacement parameter CR. The combination of the three is MSG = TNTF || NTF || CR. Member A uses SK A Sign MSG to get SIG A =SIGN(MSG,SK A ).

[0080] A calculates the pointer Pos = F PK (TNTF), take out the key K from the asymmetric key pool according to Pos i As the private key of the upper layer, the chip key KR 0 As the subordinate's public key.

[0081] A calculates the communication key Since the enemy cannot crack and obtain KR 0 , so it is very difficult for the enemy to predict K TA .

[0082] A calculates the session key KS A =MAC(TNTF,K TA ).

[0083] A Using KS A About NTF||CR||SIG A Encryption to obtain encrypted information {NTF||CR||SIG A}KS A , calculate the message authentication code MAC(ID A ||MSG||SIG A , K.S. A ).

[0084] A will M A Sent to the lower-level nodes, the message sent can be expressed as M A =ID A ||TNTF||{NTF||CR||SIG A}KS A ||MAC(ID A ||MSG||SIG A , K.S. A ).

[0085] A sends M A Then, according to the replacement parameter CR used this time, K0 is replaced in turn using the method described above. i Replace with K0' i =K0 i *CR, KR 0 Replaced by KR' 0 =KR0 CR modp. And the replacement parameter CR used this time is recorded in the security chip.

[0086] B receives M A Then, according to the method described in case 1.2, obtain TB The same communication key K TB , further calculations are performed to obtain KS A The same session key KS B =MAC(TNTF,K TB ). Use the session key KS B To M A Decryption and message authentication are performed. After verification, the public key PK of the 0th layer node stored in the local security chip is used A Verification SIG A If node B has a lower-level node, proceed to step 2. If node B has no lower-level node, replace K1 with the replacement parameter CR used this time. i Replaced by K1' i =K1 i CR modp, KR 1 Replaced by KR' 1 =KR 1 CR modp, and record the replacement parameter CR used this time into the security chip.

[0087] Based on the content in NTF, X's security chip can generate the same session key in the security chip and decrypt the encrypted message sent by A to the lower-level node. However, since it finds itself as an untrusted node from NTF, it will not transmit the decrypted information outside the security chip, nor replace the key pool and chip key, and abandon the decryption of all subsequent messages or trigger the self-destruction mechanism. Therefore, X will not be able to carry out subsequent group communication, thereby ensuring the safety of other group members.

[0088] Step 2: Layer 1 nodes forward the message.

[0089] After the first layer node B completes all steps in step 1 except the key update, it sends MSG||SIG A Passed to the second layer node C.

[0090] B uses the above method to obtain the session key KS between C BC , B uses KS BC About NTF||CR||SIG A Encryption to obtain encrypted information {NTF||CR||SIG A}KS BC, calculate the message authentication code MAC(ID B ||MSG||SIG A , K.S. BC ).

[0091] B will M B Sent to the lower-level nodes, the message sent can be expressed as M B =ID B ||TNTF||{NTF||CR||SIG A}KS BC ||MAC(ID B ||MSG||SIG A , K.S. BC ).

[0092] B sends M B Then, according to the replacement parameter CR used this time, the asymmetric key pool and chip key are replaced using the method described above, that is, K1 i Replaced by K1' i =K1 i CR modp, KR 1 Replaced by KR' 1 =KR 1 CR mod p. And the replacement parameter CR used this time is recorded in the security chip.

[0093] Step 3: Layer 2 nodes forward the message.

[0094] Layer 2 node C receives M B Then, obtain the session key KS with B according to the method described in step 1. CB To M B Perform decryption and message authentication.

[0095] If node C has subordinate nodes, it will continue to forward the message and replace the key after the message is sent;

[0096] If node C has no subordinate nodes, the key is directly replaced.

[0097] The process of replacing the key is as follows:

[0098] According to the replacement parameter CR used this time, use the method described above to replace K2 i Replaced by K2' i =K2 i CR mod p, KR 2 Replaced by KR' 2 =KR 2 CRmod p (if C is the last layer node, then KR' 2 =KR 2 *CR). After the replacement is completed, the current CR is recorded in the security chip.

[0099] Case 2.2: The untrusted member is layer 2 node X.

[0100] If the untrusted member X is a layer 2 node, then step 1 is executed according to the process in situation 2.1, that is, A sends a message to the layer 1 node. Then, steps 2 and 3 in situation 2.1 are executed to update the key pool of the lower layer node.

[0101] Similarly, since X's security chip finds itself to be an untrusted node, it will not transmit the decrypted information outside the security chip, nor replace the key pool and chip key, and abandon the decryption of all subsequent messages or trigger the self-destruction mechanism. Therefore, X will not be able to carry out subsequent group communication, thereby ensuring the safety of other group members.

[0102] Embodiment 3: Group communication with newly added trusted members.

[0103] Assume that the group administrator is A, another trusted member in the group is B, and the newly added trusted member is Y. Based on Y's layer number, A allocates the chip key and asymmetric key pool of the current group member of this layer to Y.

[0104] A generates a second description message NTF for declaring Y legal, and generates a timestamp TNTF for the second description message. Let CR = 1, that is, the parties do not perform key replacement. The subsequent steps are the same as in Example 2, that is, notifying members of each layer layer by layer.

[0105] In summary, with the help of the above technical solution of the present invention, the present invention realizes a group communication method and system based on a hierarchical asymmetric key pool. This patent combines the asymmetric key pool and the chip key, and further enhances the security of the use of the asymmetric key pool in the scenario of group communication, so that in the extreme case where the asymmetric key pool is cracked, the security of the group communication based on the asymmetric key pool can still be guaranteed. Because the keys of both parties are also protected by the chip key, when the chip key can be guaranteed not to be cracked, the communication between the two parties will not be cracked because the asymmetric key pool is cracked; the method for updating the key pool of the present patent can update the key pool without transmitting the update key, and since the calculation amount of the update key is small, the key pool update takes less time; for group communication, the key transmission amount of the key update scheme of the present patent is very small and easy to implement; in the group communication system based on the asymmetric key pool of the present patent, the status of all members with the group key pool is divided into levels, and the protection measures and key pools of different levels are different. Important-level members have good protection measures and are not easily captured; unimportant-level members have relatively poor protection measures or a more unsafe working environment, but because their key pool is calculated based on the chip key, replacement parameters and the key pool of important-level members, even if the enemy obtains the key pool, it cannot deduce the key pool of other nodes without the chip key and replacement parameters. Once its security chip finds itself as an untrusted node, it will not transmit decrypted information outside the security chip, nor will it replace the key pool and chip key, and will abandon the decryption of all subsequent messages or trigger the self-destruction mechanism, so subsequent group communication is impossible. Therefore, even if it is captured, the impact is not significant and will not cause the failure of the entire group communication system.

[0106] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0107] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A group communication method based on a hierarchical asymmetric key pool, characterized in that: The nodes in the group are divided into multiple levels according to the permissions. Each group node has the identity list of the current group. Each identity information contains the level number of the node. The administrator is the highest level. The group node security chip stores the chip key, replacement parameters and administrator public key of this level. The administrator security chip also stores the lowest level chip key, chip key, replacement parameters and administrator public and private keys of this level. The memory outside the security chip of the common node and the administrator node stores the asymmetric key pool of this level. The chip key and asymmetric key pool are updated using replacement parameters during the communication process, including the following steps: (1) If the group nodes of the same layer communicate, the communicating parties select an asymmetric key from the asymmetric key pool of the current layer and a chip key of the current layer according to a pre-set asymmetric key selection method, calculate a communication key based on the Diffie-Hellman key exchange protocol, and calculate a first session key based on the communication key; (2) If group nodes at different layers communicate with each other, the group node at the higher layer selects an asymmetric key from the asymmetric key pool at the current layer as the private key of the current layer according to a pre-set asymmetric key selection method, uses the chip key of the current layer as the public key of the lower layer, calculates a communication key based on the private key of the current layer and the public key of the lower layer based on the Diffie-Hellman key exchange protocol, and calculates a first session key based on the communication key; (3) The lower-layer group node selects an asymmetric key from the asymmetric key pool of the current layer as the public key of the upper layer according to a pre-set asymmetric key selection method, and uses the chip key of the current layer as the private key of the current layer; the communication key is calculated based on the Diffie-Hellman key exchange protocol using the private key of the current layer and the public key of the upper layer, and the first session key that is the same as that of the upper-layer group node is calculated using the communication key; (4) The group nodes communicate using the first session key; The updating of the chip key using the replacement parameter comprises the following steps: Through the Diffie-Hellman key exchange protocol, the chip key of the lower layer is transformed into the chip key of the upper layer; the administrator generates a new replacement parameter to update the chip key; The method of updating the asymmetric key pool by using the replacement parameters comprises the following steps: initializing the administrator layer key pool to a key pool composed of true random numbers, dividing the key pool of the current layer into multiple segments of subkeys, calculating each segment of subkeys by using the DiffieHellman key exchange protocol to obtain the segment of subkeys of the lower layer; and then concatenating the multiple calculation results in the order of the corresponding subkeys to obtain the key pool of the lower layer; The administrator generates new replacement parameters to update multiple sub-keys. After the update is completed, the multiple calculation results are spliced ​​in the order of the corresponding sub-keys to obtain the updated key pool.

2. The group communication method based on a hierarchical asymmetric key pool according to claim 1, characterized in that: When a group communication node sends a notification, layer-by-layer communication is performed, and the layer-by-layer communication method includes the following steps: the group administrator obtains a second session key according to the method described in step (2), uses a private key to sign a first message containing a notification, a replacement parameter, and a current timestamp to obtain signature information, encrypts a second message containing a notification, a replacement parameter, and the signature information using the second session key to obtain a third message and calculates a first message verification code, combines the administrator identity information, the current timestamp, the third message, and the first message verification code to obtain a first encrypted message and sends it to a lower-level node, uses the replacement parameter to update the asymmetric key pool, and records the replacement parameter used this time into the security chip.

3. The group communication method based on a hierarchical asymmetric key pool according to claim 2, characterized in that: After receiving the message, the trusted node obtains the second session key according to the method described in step (3), uses the second session key to decrypt the first encrypted message, and uses the administrator public key stored in the local security chip to verify the signature information.

4. The group communication method based on a hierarchical asymmetric key pool according to claim 3, characterized in that: When the sending trusted node has no lower-level node, the asymmetric key pool is updated using the replacement parameters, and the replacement parameters used this time are recorded in the security chip; When the trusted node has a lower-level node, the trusted node transmits the combination of the first message and the signature information to the lower-level node. The trusted node obtains the third session key according to the method described in step (2), encrypts the second message with the third session key to obtain the fourth message, calculates the second message verification code, combines the trusted node identity information, the current timestamp, the fourth message and the second message verification code to obtain the second encrypted message and sends it to the lower-level node. The asymmetric key pool and the chip key are updated using the replacement parameters, and the replacement parameters used this time are recorded in the security chip.

5. The group communication method based on a hierarchical asymmetric key pool according to claim 4, characterized in that: After receiving the second encrypted message, the lower-level node obtains the third session key according to the method described in step (3), uses the third session key to decrypt the second encrypted message, and verifies the signature using the administrator public key stored in the local security chip.

6. The group communication method based on a hierarchical asymmetric key pool according to claim 5, which occurs when one node is untrustworthy, is characterized in that: The illegal information of untrusted nodes is used as a notification to notify nodes at each layer layer by layer.

7. The group communication method based on a hierarchical asymmetric key pool according to claim 5, which occurs when a new trusted node is added, is characterized in that: The administrator allocates the chip key and asymmetric key pool of the current node in the group to the trusted node according to the layer number of the newly added trusted node, and notifies the nodes at each layer layer by layer. The notification is a legitimate message of the newly added trusted node. The parties do not replace the key in this communication process.

8. A group communication system based on a hierarchical asymmetric key pool, characterized in that: The system includes an administrator and a group node. The administrator and the group node communicate according to the method described in any one of claims 1 to 7. The administrator and the group node are both equipped with a security chip and have an anti-disassembly function. The administrator is the highest level and has the ability to issue key cards.

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