A fog-blockchain assisted smart grid aggregated authentication method

Abstract

This invention discloses a fog-blockchain-assisted smart grid aggregation authentication method. First, a key generation center initializes and generates a public-private key pair. Participants generate their own identity key pairs and send their public keys to the key generation center. The key generation center generates a signature key pair for each participant and sends it to them. Participants run key verification; if verification is successful, they accept the key. Fog nodes initiate data collection from a group of meters using broadcast signatures based on information in the blockchain. The meters verify the broadcast information based on their information in the blockchain; if verification is successful, the meter's public key information is stored in a local list. The meters signify the collected data, and the fog nodes aggregate and designify the ciphertext. The fog nodes initiate key negotiation with the control center and cloud storage center, and then use the negotiated key for batch data transmission. When a participant engages in illegal activity, the key generation center can apply to the blockchain to delete the violator's information.

Description

Technical Field

[0001] This invention belongs to the field of information security technology, and specifically relates to a fog-blockchain assisted smart grid aggregation authentication method. Background Technology

[0002] Given the heterogeneity of smart grid devices, the collection and aggregation of grid data involves two parts: collecting large amounts of small / short data from smart meters, and transmitting the aggregated large amounts of data to a storage / processing center. Without fog assistance, the direct interaction between numerous terminal devices and cloud servers over the network leads to heavy communication overhead and high latency (low quality of service), thus prompting the proposal of several fog-assisted data sharing models. However, most existing models only consider how fog nodes verify distributed and decentralized smart meters, neglecting the potential security risks posed by the fog collector itself. Furthermore, most schemes only use fog nodes as data collectors without fully utilizing local data processing, which not only wastes resources but also fails to fundamentally alleviate the burden on cloud servers.

[0003] Industry and academia agree that the security of smart grid systems heavily relies on authentication technologies. For short data transmissions, public-key encryption schemes (such as aggregate signature cryptography) achieve secure and efficient data transfer. However, due to the complexity and ciphertext overhead of public-key encryption, it is unsuitable for transmitting large amounts of aggregate data. The cryptographic primitive of authentication key negotiation has been proposed to address this issue by generating symmetric-encrypted session keys for secure transmission of large amounts of data at once. Extensive research concludes that designing a hybrid data collection framework for smart grids with heterogeneous devices and complex communication patterns to achieve optimal efficiency and provide high-quality services is of significant research value.

[0004] Secure key management (such as upgrades and revocations) is the cornerstone of secure authentication. Relying on public key infrastructure (PKI) or centralized servers (e.g., key generation centers, KGCs) for key management can lead to security vulnerabilities; for example, data stored on the server could be tampered with and deleted during an attack. Blockchain is increasingly attempting to replace traditional centralized servers for managing device keys due to its advantages such as distribution, transparency, and tamper resistance. First, users can quickly obtain the necessary public key information by requesting the blockchain (a distributed system) before performing authentication. Second, any operation in a smart contract, such as writing, updating, and querying, requires consensus before execution. This characteristic makes blockchain suitable for data integrity protection and auditing. However, when combining blockchain with smart grids, privacy trade-offs must be considered.

[0005] In conclusion, designing an efficient and secure identity authentication and fog assistance scheme for heterogeneous data collection in smart grids is both challenging and of practical value. Summary of the Invention

[0006] To address the aforementioned issues, this invention considers the resource heterogeneity of three-layer devices in a smart grid scenario and designs a fog-blockchain-assisted smart grid aggregation authentication method. This method employs certificate-free aggregation authentication to achieve mutual authentication between the underlying electricity meters and fog nodes, while using key negotiation to complete batch data sharing between fog nodes and upper-layer servers. Furthermore, with the assistance of a distributed blockchain, it completes identity management for all participants and integrity auditing of electricity meter data.

[0007] First, the key generation center initializes and generates public and private key pairs for the system. Participants (electricity meters, fog nodes, cloud storage center, and control center) generate their own identity key pairs and then send their public keys to the key generation center. The key generation center generates signature key pairs for each participant and sends them to the participants, while also storing them in the blockchain. Participants run key verification; if verification is successful, they accept the key; otherwise, they send an adjudication request to the blockchain. Fog nodes initiate data collection from a group of electricity meters based on information in the blockchain through broadcast signatures. Electricity meters verify the broadcast information based on their information in the blockchain; if verification is successful, they store the meter's public key information in their local list. Electricity meters signify the collected data, a step divided into pre-signature and full signature, and then send the ciphertext to the corresponding fog node, while simultaneously storing the hash values ​​of the plaintext and ciphertext in the blockchain. Fog nodes aggregate and designify the ciphertext. Fog nodes initiate key negotiation with the control center and cloud storage center, and then use the negotiated key for batch data transmission. When a participant engages in illegal behavior, the key generation center can apply to the blockchain to delete the violator's information. When data may be tampered with, any participant can apply to the blockchain for an integrity audit.

[0008] To achieve the above objectives, the technical solution adopted by this invention is: a fog-blockchain-assisted smart grid aggregation authentication method, comprising the following steps:

[0009] S1, System Initialization: The key generation center initializes and generates the system public and private keys, publishes the system public key, and keeps the system private key confidential; the expressions for the system public key MPK and system private key MSK are as follows:

[0010] MPK = (G, G T ,p,e,P,P pub ,P′ pub SymE β SymD β ,H1,H ′ 1,H2,H3,H4)

[0011] MSK=(α,β,γ)

[0012] Among them, G and G T Let G be a multiplicative group of order p, where p is a generator of G. pub =αP,P′ pub =γP) are two elements calculated according to MSK; e:G×G→G T It is a symmetric bilinear mapping; H1, H ′ H1, H2, H3, and H4 are collision-resistant hash functions; (SymE) β SymD β (α,β,γ) is a symmetric encryption and decryption algorithm using key β; (α,β,γ) is a subset of the group. A random value randomly selected from the group of integers modulo p;

[0013] S2, Participants generate their own identity key pairs: Participants include four types: electricity meters, fog nodes, cloud storage centers, and control centers. Each participant generates its own public and private key pair, sends the public key to the key generation center, and keeps the private key secret. id,1 SK id,1 The expression for ) is:

[0014] PK id,1 =x id P,

[0015] Where, x id From The element is randomly selected from the data;

[0016] S3, Complete Key Generation: The key generation center generates a complete key pair for the participants based on their identity public key, including the pseudonym Pseud. id Second public key PK id,2 Second private key SK id,2 and verification key VK id The public key is stored on the blockchain, while the remaining secrets are returned to the participants. If the participant is a smart meter, the complete key (Pseud) is... id PK id,2 SK id,2 VK id The expression for ) is:

[0017] Pseud id =SymE β (ID||PK id,1 ||T),PK id,2 =v id P,SK id,2

[0018] =vid +αH1(ID||PK id,1 ||T)mod p,VK id

[0019] =SK id,2 P+v id PK id,1 ;

[0020] Where T is the key validity period; v id From The element is randomly selected from the data;

[0021] If the participant is one of the other three categories, the key generation center will also generate a third private key SK in addition to the keys generated above. id,3 SK id,3 The expression is:

[0022] SK id,3 =γH3(ID||PK id,1 ||T);

[0023] S4, Key Verification: After receiving the complete key pair, the participant performs verification. First, the private key SK is sent to the participant. id Decomposed into (SK) id,1 SK id,2 SK id,3 ), will PK id Decomposed into (PK) id,1 PK id,2 Then, the key is substituted into the verification formula. If the equation holds true, all keys are accepted; otherwise, a ruling request is sent to the blockchain. If the participant is a smart meter, the expression of the verification formula is:

[0024] SK id,2 P = PK id,2 +H1(ID||PK id,1 ||T)P pub VK id

[0025] =SK id,2 P+x id PK id,2 ;

[0026] If the participant belongs to one of the other three categories, the following formula also needs to be validated:

[0027] SK id,3 P = H3(ID||PK) id,1 ||T)P′ pub ;

[0028] S5, Broadcast Signature: Fog node signs a message MSG s Get a signature The signature and its identity are then broadcast to a group of smart meters; the signature The expression is:

[0029] R i =r i P,σ i =h(SK fi,1 +SK fi,2 )+r i (mod p);

[0030] Among them, MSG s It is a fixed-length string message, r i From The element is randomly selected from the data; h = H′1(ID) fi ||R i ||PK id,1 ||PK id,2 ||T||MSG s ) is a hash value;

[0031] S6, Signature Verification: Upon receiving the broadcast signature, the smart meter reads the public key from the blockchain based on the identity and uses it to determine the legitimacy of this fog node using the following formula; the expression of the formula is:

[0032] σ i P = h′(PK) fi,1 +H1(ID fi ||PK fi,1 ||T)P pub +PK fi,2 )+R i ;

[0033] Where h′=H′1(ID) fi ||R i ||PK id,1 ||PK id,2 ||T||MSG s );

[0034] S7, Signature: Smart Meter ID j The data is signed to obtain ciphertext, and then the ciphertext and its pseudonym are sent to the corresponding fog node; this step is divided into two steps: pre-signature and full signature.

[0035] S71, Pre-signature: After determining the response fog node, the smart meter can perform pre-signature to generate a semi-ciphertext, the semi-ciphertext being PCT. j =(u j U j ,K j ,h j,1 The formula for ) is:

[0036] U j =u j P,

[0037] K j =u j (PK fi,1 +H1(ID fi ||PK fi,1 ||T)P pub +PK fi,2 ,

[0038] h j,1 =H2(ID) fi ||PK fi,1 ||PK fi,2 ||U j ||K j );

[0039] Among them, u j Is from The element is randomly selected from the data;

[0040] S72, Complete Signature: Smart Meter's Data File F j,t Perform a complete signature, then send the complete ciphertext and its pseudonym to the corresponding fog node; the complete ciphertext CT j =(Pseud smj U j C j ,σ j ,θ f,t The formula for ) is:

[0041] U j =u j P,

[0042] σ j =h j,2 (SK smj,1 +SK smj,2 )+u j (mod p);

[0043] Among them, Pseud smj It's a pseudonym for an electricity meter, θ f,t It is an aggregate identifier, h j,2 =H4(C j ||U j ||θ f,t ||T);

[0044] S8, Signature Aggregation: After receiving a batch of ciphertext, the fog node aggregates the signatures to obtain aggregated ciphertext. The hash value of the aggregated ciphertext is stored in the blockchain. The expression of the aggregated ciphertext is as follows:

[0045] CT=({Pseud smj U j C j},σ=Σσ j ,θ f,t );

[0046] Where σ is the aggregated signature;

[0047] S9, Decryption: The fog node decrypts the collected ciphertext to obtain a set of plaintext files {F j,t The file is then compressed locally; the hash value of the compressed file is stored in the blockchain; the decryption formula consists of two parts: signature verification and decryption, where the expression for the signature verification formula is:

[0048] σP=Σ(h j ′ ,2 (PK smj,1 +H1(Pseud smi ||PK smi,1 ||T)P pub +PK smj,2 ))

[0049] +ΣU j ,

[0050] Among them, h j ′ ,2 =H4(C j ||U j ||θ f,t ||T).

[0051] The expression for the decryption formula is:

[0052]

[0053] S10, Key Negotiation: The fog node negotiates a key with the server (control center or cloud storage center). Two values ​​A, B∈G are pre-shared through a signature. After successful signature verification, these two values ​​are accepted, and the negotiated key is then used for batch file transfers. The expression for the negotiated key on the fog node side is:

[0054] Q s =H3(ID) s ||PK s,1 ||T),Seed=e(aQ s ,P p′ ub )e(SK fi,3 (B)

[0055] SnK = KDF seed (A||B||ID f ||ID s ||aB)

[0056] Among them, ID s It is the identity, ID, of the control center or cloud storage center. f It is the identity of a fog node, PK s,1 It is its public key, and T is the key's validity period. These are the values ​​chosen by the fog node, A = aP, SK fi,3 B is the private key of the fog node, B = bP∈G is the value pre-shared to the fog node by the control center or cloud storage center, and KDF is a key derivation function.

[0057] The expression for the negotiation key on the server side is:

[0058] Q f =H3(ID) f ||PK f,1 ||T),Seed=e(bQ f ,P p ′ ub )e(SK s,3 A),

[0059] SnK = KDF seed (A||B||ID f ||ID s ||bA),

[0060] Among them, ID f It is the identity, ID of the fog node. s Is it the identity of a control center or cloud storage center? PK f,1 It is its public key, and T is the key validity period. These are server-selected values, B = bP, SK s,3 It is the server's private key, and A = aP∈G is the value that the fog node pre-shares with the server;

[0061] S11, Device Revocation: When a participant engages in illegal activity, the key generation center can apply to the blockchain to delete the violator's information. If the participant's public key cannot be found in the blockchain, identity verification cannot be performed.

[0062] S12, Data Integrity Audit: When data may have been tampered with, any participant can request an integrity audit from the blockchain. The blockchain audits the data integrity based on the hash value stored in the ledger, identifying those responsible for data tampering.

[0063] To achieve the above objectives, the present invention also adopts the following technical solution: a fog-blockchain assisted smart grid aggregation authentication product, comprising a computer program, wherein the computer program, when executed by a processor, implements the steps of any of the methods described above.

[0064] Compared with the prior art, the technical advantages of the present invention are as follows:

[0065] (1) This invention designs a layered data sharing framework for smart grids, consisting of smart meters, fog nodes, a server layer (control center or cloud server), and a blockchain. The blockchain replaces the traditional PKI for key management, and fog nodes collect and process (aggregate verification) data locally through mutual authentication with smart meters.

[0066] (2) A fog-blockchain-assisted certificateless aggregate signature scheme (CLASC) is designed for mutual authentication between smart meters and fog nodes. In addition, pseudonym technology and online / offline technology are also adopted to protect privacy and reduce overhead.

[0067] (3) This invention uses authentication key protocol technology to realize batch data transmission between fog nodes and servers. It is worth mentioning that the control center usually obtains data from the cloud, but for emergency situations and low-latency services, the cloud can choose to communicate directly with fog nodes to obtain data.

[0068] (4) Use the hash value of the identity information and ciphertext of the consortium blockchain storage devices (electricity meters and fog nodes) to manage (including revocation and update) the devices and achieve integrity auditing. Attached Figure Description

[0069] Figure 1 This is a system framework diagram of the method of the present invention;

[0070] Figure 2 This is a flowchart of the method of the present invention. Detailed Implementation

[0071] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, and the terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0072] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0073] Example 1

[0074] The symbols and their definitions in this scheme are shown in Table 1:

[0075] Table 1

[0076]

[0077]

[0078] like Figure 1 As shown, the fog-blockchain-assisted smart grid aggregation authentication method proposed in this invention includes four participants:

[0079] (1) Key Generation Center (KGC): This is a trusted server responsible for system initialization and key generation. In addition, it collaborates with the blockchain to manage keys.

[0080] (2) Smart meter (SM): It is an Internet of Things terminal device equipped with security components to store keys and pseudonyms.

[0081] (3) Cloud Storage Server (CSS): It is a central server used to store historical data of smart grid.

[0082] (4) Blockchain (BC): is a permissioned distributed ledger system. In our scheme, devices and servers perform authentication and integrity audits based on two types of data stored in the blockchain.

[0083] (5) Control Center (CC): This is a group of resource-rich servers. For simplicity, we will consider the CC as a participant that is responsible for centralized data processing through communication with the CSS and BC.

[0084] (6) Fog Nodes (FNs): These are IoT edge servers (e.g., base stations) that possess more resources than terminal devices. In our solution, fog nodes are used to collect and aggregate data, process data locally (verify and deseal), and communicate with the server.

[0085] Figure 2 The data interaction process of the entire solution, and the fog-blockchain-assisted smart grid aggregation authentication method, are illustrated below. The specific implementation steps are described as follows:

[0086] Step S1: System initialization. The input is a security parameter κ. The key generation center performs the following steps:

[0087] (1.1) Choose two multiplicative cyclic groups G and G' of order p. T A bilinear pair e: G×G→G T P is a generator of group G.

[0088] (1.2) Select five collision-resistant hash functions: {0,1} * →{0,1} l H3:{0,1} * →G,

[0089] (1.3) Choose a key derivation function (KDF) and a pair of symmetric encryption / decryption algorithms using key β. β SymD β ).

[0090] (1.4) Randomly select an element α, β, Calculate P pub =αP,P′ pub =γP.

[0091] (1.5) Publicly disclose the system public key and keep the private key confidential. The expressions for the system public key MPK and the system private key MSK are as follows:

[0092] MPK = (G, G T ,p,e,P,P pub ,P′ pub SymE β SymD β (H1,H′1,H2,H3,H4)

[0093] MSK=(α,β,γ)

[0094] Step S2: Participants generate their own identity key pairs. Participants include four types: electricity meters, fog nodes, cloud storage centers, and control centers. Each participant generates its own public-private key pair. This includes the following steps:

[0095] (2.1) Participants from the group Randomly select a random value x id Set as the identity private key.

[0096] (2.2) Calculate the public key PK id,1 =x id P.

[0097] (2.3) Send the identity public key to the key generation center and keep the identity private key secret.

[0098] Step S3: Complete Key Generation. The key generation center generates a complete key pair for the participants based on their identity public key, including the pseudonym Pseud. id Second public key PK id,2 Second private key SK id,2 And verify the key. This includes the following steps:

[0099] (3.1) If the participant is a smart meter: the key generation center calculates the pseudonym Pseud using the participant's identity ID and public key. id =SymE β (ID||PK id,1 ||T).

[0100] (3.2) From the group Random value v is randomly selected from the middle id Calculate the second public key PK id,2 =v id P, second private key SK id,2 =v id +αH1(ID||PK id,1 ||T)mod p, and verification key VK id =SK id,2 P+v id PK id,1 Where T is the key validity period.

[0101] (3.3) If the participants are from the other three categories, the key generation center shall generate a third private key SK in addition to generating the keys mentioned above. id,3 =γH3(ID||PK id,1 ||T).

[0102] (3.4) The public key is stored in the blockchain, and the remaining keys are secretly returned to the participants.

[0103] Step S4: Key Verification. After receiving the complete key pair, the participant verifies it. This includes the following steps:

[0104] (4.1) Transfer the private key SK id Decomposed into (SK) id,1 SK id,2 SK id,3 ), will PK id Decomposed into (PK) id,1 PK id,2 ).

[0105] (4.2) Substitute into the verification formula. If the participant is a smart meter, the expression of the verification formula is:

[0106] SK id,2 P = PK id,2 +H1(ID||PKid,1 ||T)P pub VK id

[0107] =SK id,2 P+x id PK id,2 ;

[0108] If the participant belongs to one of the other three categories, the following formula also needs to be validated:

[0109] ′

[0110] SK id,3 P = H3(ID||PK) id,1 ||T)P pub ;

[0111] (4.3) If the equation is true, then accept all keys; otherwise, initiate a ruling request to the blockchain.

[0112] Step S5: Broadcast Signature. The fog node signs a message MSG. s Obtain the signature φ. This involves the following steps:

[0113] (5.1) From the group Randomly select a random value r i Calculate R i =r i P, h =

[0114] ′

[0115] H1(ID fi ||R i ||PK id,1 ||PK id,2 ||T||MSG s ).

[0116] (5.2) Calculate the signature σ i =h(SK fi,1 +SK fi,2 )+r i (mod p).

[0117] (5.3) Output signature φ = (MSG s ,R i ,σ i ).

[0118] Step S6: Signature Verification: Upon receiving the broadcast signature, the smart meter performs identity verification. This includes the following steps:

[0119] (6.1) Read the public key from the blockchain based on the fog node identity.

[0120] (6.2) Calculate h′ =H1 ′ (ID fi ||R i ||PK id,1 ||PK id,2 ||T||MSG s Determine whether the following equation is true:

[0121] σ i P = h ′ (PK fi,1 +H1(ID fi ||PK fi,1 ||T)P pub +PK fi,2 )+R i .

[0122] (6.3) If true, add the public key of this fog node to the local trusted list. Otherwise, ignore this message.

[0123] Step S7: Signature: Smart Meter ID j The encrypted data is obtained by signing the encryption. This involves the following steps:

[0124] (7.1) Pre-signature: After determining the response fog node, the smart meter can perform pre-signature to generate semi-ciphertext.

[0125] (7.1.1) From the group Random value u is randomly selected from the middle j Calculate U j =u j P.

[0126] (7.1.2) Calculate K j =u j (PK fi,1 +H1(ID fi ||PK fi,1 ||T)P pub +PK fi,2 and h j,1 =H2(ID) fi ||PK fi,1 ||PK fi,2 ||U j ||K j ).

[0127] (7.1.3) Output semi-ciphertext PCT j =(u j U j ,K j ,h j,1 ).

[0128] (7.2) Complete authentication: The smart meter authenticates the collected data file Fj,t Perform a complete signature verification.

[0129] (7.2.1) Using symmetric encryption for computation

[0130] (7.2.2) Select timestamp T and calculate h. j,2 =H4(C j ||U j ||θ f,t ||T) and σ j =h j,2 (SK smj,1 +SK smj,2 )+u j (mod p).

[0131] (7.2.3) Conceal the CT j =(Pseud smj U j C j ,σ j ,θ f,t ) and its pseudonym are sent to the corresponding fog node.

[0132] Step S8: Signature Aggregation. After receiving a batch of ciphertext, the fog node aggregates the signatures within it. This stage includes the following steps:

[0133] (8.1) Calculate the aggregate signature σ = Σσ j .

[0134] (8.2) Output aggregated ciphertext CT = ({Pseud) smj U j C j},σ=Σσ j ,θ f,t Meanwhile, the hash value of the ciphertext CT is stored in the blockchain.

[0135] Step S9: Decryption. The fog node decrypts the collected ciphertext. This stage includes the following steps:

[0136] ′

[0137] (9.1) Calculate h j,2 =H4(C j ||U j ||θ f,t ||T).

[0138] (9.2) Verify whether the following equation holds true:

[0139]

[0140] If the equation is false, refuse to receive the encrypted message. Otherwise, continue decryption. (9.3)

[0142] calculate

[0143]

[0144] (9.4) Output a set of plaintext files {F j,t The file's hash value is then stored in the blockchain.

[0145] Step S10: Key Negotiation. The fog node negotiates a key with the server (control center or cloud storage center). This stage includes the following steps:

[0146] (10.1) Fog nodes from the group Random values ​​are selected from the middle. Calculate A = aP. Sign A using the private key and send the signature to the server to initiate a key exchange request.

[0147] (10.2) The server verifies the signature. If this fails, the key negotiation request is ignored. Otherwise, it retrieves the signature from the group. Random values ​​are selected from the middle. Calculate B = bP. Sign B using the private key and send the signature to the fog server.

[0148] (10.3) The fog server verifies the signature; if successful, it receives B. It reads the server's identity and public key from the blockchain and calculates Q. s =H3(ID) s ||PK s,1 ||T) and Seed=e(aQ s ,P′ pub )e(SK fi,3 B). Calculate the negotiation key SnK = KDF seed (A||B||ID f ||ID s ||aB).

[0149] (10.4) The server calculates Q based on the fog node's identity and public key. f =H3(ID) f ||PK f,1 ||T) and Seed=e(bQ) f ,P′ pub )e(SK s,3 A). Calculate the negotiation key SnK = KDF seed (A||B||ID f ||ID s ||bA).

[0150] Step S11, Device Revocation. When a participant engages in illegal activity, the key generation center can apply to the blockchain to delete the violator's information. If the participant's public key cannot be found in the blockchain, identity verification cannot be performed.

[0151] Step S12, Data Integrity Audit. When data may have been tampered with, any participant can request an integrity audit from the blockchain. The blockchain audits the data integrity based on the hash value stored in the ledger, identifying the person responsible for the data tampering.

[0152] This embodiment considers the many-to-one communication between the underlying electricity meters and fog nodes, and the batch data transmission between fog nodes and upper-layer servers in smart grid scenarios. It designs a fog-blockchain-assisted certificateless aggregation authentication method for smart meters. This method uses certificateless aggregation authentication technology to achieve bidirectional authentication between the underlying electricity meters and fog nodes, ensuring the reliability and security of the data source. Simultaneously, key negotiation technology is used to achieve batch data transmission between fog nodes and upper-layer servers, reducing the overall communication overhead of the system. Furthermore, this invention uses blockchain to maintain an immutable user list, enabling efficient user revocation. Additionally, the device stores the hash value of the data in the blockchain for subsequent integrity auditing.

[0153] The technical means disclosed in this invention are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features.

Claims

1. A fog-blockchain-assisted smart grid aggregation authentication method, characterized in that: Includes the following steps: S1, System Initialization: The key generation center initializes and generates the system public and private keys, publishes the system public key, and keeps the system private key confidential; the expressions for the system public key MPK and system private key MSK are as follows: MPK=(G,G T ,p,e,P,P pub ,P′ pub ,SymE β ,SymD β ,H1,H′1,H2,H3,H4) MSK=(α,β,γ) Among them, G and G T Let G be a multiplicative group of order p, where p is a generator of G. pub =αP,P′ pub =γP are two elements calculated according to MSK; e:G×G→G T It is a symmetric bilinear mapping; H1, H2, H3, H4 are collision-resistant hash functions; SymE β SymD β It is a symmetric encryption and decryption algorithm using key β; α, β, γ are subgroups. Random values ​​randomly selected from the data, where Let p be the group of integers modulo p; S2, Participants generate their own identity key pairs: Participants include four types: electricity meters, fog nodes, cloud storage centers, and control centers. Each participant generates its own public and private key pair, sends the public key to the key generation center, and keeps the private key secret. id,1 SK id,1 The expression for ) is: PK id,1 =x id P, Where, x id From The element is randomly selected from the data; S3, Complete Key Generation: The key generation center generates a complete key pair for the participants based on their identity public key, including the pseudonym Pseud. id Second public key PK id,2 Second private key SK id,2 and verification key VK id The public key is stored on the blockchain, while the remaining secrets are returned to the participants. If the participant is a smart meter, the complete key (Pseud) is... id PK id,2 SK id,2 VK id The expression for ) is: Pseud id =SymE β (ID||PK id,1 ||T),PK id,2 =v id P,SK id,2 =v id +αH1(ID||PK id,1 ||T)mod p,VK id =SK id,2 P+v id PK id,1 ; Where T is the key validity period; v id From The element is randomly selected from the data; If the participant is one of the other three categories, the key generation center will also generate a third private key SK in addition to the keys generated above. id,3 SK id,3 The expression is: SK id,3 =γH3(ID||PK id,1 ||T); S4, Key Verification: After receiving the complete key pair, the participant performs verification; first, the private key SK is sent to the participant. id Decomposed into (SK) id,1 SK id,2 SK id,3 ), will PK id Decomposed into (PK) id,1 PK id,2 Then, the key is substituted into the verification formula. If the equation holds true, all keys are accepted; otherwise, a ruling request is sent to the blockchain. If the participant is a smart meter, the expression of the verification formula is: SK id,2 P=PK id,2 +H1(ID||PK id,1 ||T)P pub ,VK id =SK id,2 P+x id PK id,2 ; If the participant belongs to one of the other three categories, the following formula also needs to be validated: EN id,3 P=H3(ID||PK id,1 ||T)P′ pub ; S5, Broadcast Signature: Fog node signs a message MSG s Get a signature The signature and its identity are then broadcast to a group of smart meters; the signature The expression is: R i =r i P,σ i =h(SK fi,1 +SK fi,2 )+r i (towards p); Among them, MSG s It is a fixed-length string message, r i From The element is randomly selected from the data; h = H′1(ID) fi ||R i ||PK id,1 ||PK id,2 ||T||MSG s ) is a hash value; S6, Signature Verification: Upon receiving the broadcast signature, the smart meter reads the public key from the blockchain based on the identity and uses it to determine the legitimacy of this fog node using the following formula; the expression of the formula is: σ i P=h′(PK fi,1 +H1(ID fi ||PK fi,1 ||T)P pub +PK fi,2 )+R i ; Where h′=H′1(ID) fi ||R i ||PK id,1 ||PK id,2 ||T||MSG s ); Step S7 is divided into two steps: pre-signature and complete signature. S8, Signature Aggregation: After receiving a batch of ciphertext, the fog node aggregates the signatures to obtain aggregated ciphertext. The hash value of the aggregated ciphertext is stored in the blockchain. The expression of the aggregated ciphertext is as follows: CT=({Pseud smj ,U j ,C j },σ=Σσ j ,i f,t ); Where σ is the aggregated signature; Pseud smj It's a pseudonym for an electricity meter, θ f,t It is an aggregate identifier; S9, Decryption: The fog node decrypts the collected ciphertext to obtain a set of plaintext files {F j,t The file is then compressed locally; the hash value of the compressed file is stored in the blockchain; the decryption formula consists of two parts: signature verification and decryption, where the expression for the signature verification formula is: σP=Σ(h′ j,2 (PK smj,1 +H1(Pseud smj ||PK smj,1 ||T)P pub +PK smj,2 ))+ΣU j , Where, h′ j,2 =H4(C j ||U j ||θ f,t ||T); The expression for the decryption formula is: K' j =(SK fi,1 +SK fi,2 )YOU j h′ j,1 =H2(ID fi ||PK fi,1 ||PK fi,2 ||You j ||K j ),F j,t =C j ⊕h j,1 ; S10, Key Negotiation: The fog node negotiates a key with the server or cloud storage center. Two values ​​A, B∈G are pre-shared through a signature. After successful signature verification, these two values ​​are accepted, and the negotiated key is then used for batch file transfers. The expression for the negotiated key on the fog node side is: Q s =H3(ID s ||PK s,1 ||T),Seed=e(aQ s ,P′ pub )and(SK fi,3 ,B), SnK=KDF seed (A||B||ID f ||ID s ||aB) Among them, ID s It is the identity, ID, of the control center or cloud storage center. f It is the identity of a fog node, PK s,1 It is its public key, and T is the key validity period. These are the values ​​chosen by the fog node, A = aP, SK fi,3 B is the private key of the fog node, B = bP∈G is the value pre-shared to the fog node by the control center or cloud storage center, and KDF is a key derivation function. The expression for the negotiation key on the server side is: Q f =H3(ID f ||PK f,1 ||T),Seed=e(bQ f ,P′ pub )e(SK s,3 ,A), SnK=KDF seed (A||B||ID f ||ID s ||bA), Among them, ID f It is the identity, ID of the fog node. s Is it the identity of a control center or cloud storage center? PK f,1 It is its public key, and T is the key validity period. These are server-selected values, B = bP, SK s,3 It is the server's private key, and A = aP∈G is the value that the fog node pre-shares with the server; S11, Device Revocation: When a participant commits illegal acts, the key generation center applies to the blockchain to delete the violator's information; if the participant's public key cannot be found in the blockchain, identity verification cannot be performed. S12, Data Integrity Audit: When data may be tampered with, any participant can request an integrity audit from the blockchain; the blockchain audits the data integrity based on the hash value stored in the ledger and identifies the person responsible for the data tampering.

2. The fog-blockchain-assisted smart grid aggregation authentication method according to claim 1, characterized in that: Step S7 includes the following steps: S71, Pre-signature: After determining the response fog node, the smart meter performs pre-signature to generate a semi-ciphertext, the semi-ciphertext PCT j =(u j U j ,K j ,h j,1 The formula for ) is: U j =u j P,K j =u j (PK fi,1 +H1(ID fi ||PK fi,1 ||T)P pub +PK fi,2 , h j,1 =H2(ID fi ||PK fi,1 ||PK fi,2 ||U j ||K j ); Among them, u j Is from The element is randomly selected from the data; S72, Complete Signature: Smart Meter's Data File F j,t Perform a complete signature, then send the complete ciphertext and its pseudonym to the corresponding fog node; the complete ciphertext CT j =(Pseud smj U j C j ,σ j ,θ f,t The formula for ) is: IN j =in j PC j =F j,t ⊕h j,1 ,σ j =h j,2 (SK smj,1 +SK smj,2 )+u j (mod p); Among them, Pseud smj It's a pseudonym for an electricity meter, θ f,t It is an aggregate identifier, h j,2 =H4(C j ||U j ||θ f,t ||T).

3. A fog-blockchain-assisted smart grid aggregation authentication device, comprising a computer program, characterized in that: When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1-2.

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