CN110677234A - A privacy protection method and system based on homomorphic encryption blockchain - Google Patents

Abstract

The invention provides a privacy protection method and system based on a homomorphic encryption blockchain, including: each home intelligent gateway is a node, and a plurality of home intelligent gateways form a blockchain; each home intelligent gateway in the blockchain Allocate a pair of secret keys, and set the whole network secret key at the same time; divide the whole network nodes in the blockchain into special nodes and ordinary nodes, and the special nodes store the public key of each home intelligent gateway; each home intelligent gateway receives And save the information collected by the monitoring terminal collected by the sensor, and divide the information into visible information and invisible information. After the invisible information is homomorphically encrypted by the public key of the whole network, the visible information and invisible information are packaged into data packets. The private key is used to sign, and the signed data package is sent to the network through the home smart gateway; the whole network is verified for the data package; the accounting node writes all the verified data within a period of time into a new block, which is connected to the main The tail of the blockchain.

Description

A privacy protection method and system based on homomorphic encryption blockchain

technical field

The invention relates to a privacy protection method, in particular to a blockchain-based privacy data protection method.

Background technique

With the development and integration of computer technology, Internet technology and communication technology, a smart home system based on the Internet of Things (IOT) emerges as the times require. In such systems, effective device-to-device (D2D) communication largely depends on the computing capabilities of edge devices. The development of edge computing (EC) technology has brought computing capabilities closer to user. By addressing needs at the edge, it provides users with a faster response.

Currently in smart home systems, there is an ever-increasing amount of information about individual user health status and information transmitted and stored through cell phones, tablets, wireless sensors, and wearable personal health devices. Since the medical equipment in the system records the user's sensitive information, such as blood pressure (BP), heart rate (HR), respiratory rate (RR), etc., if personal sensitive information is maliciously attacked or leaked, will cause irreparable losses. Therefore, the information security and privacy protection issues in smart home edge devices have attracted the attention of many researchers. The document Security and privacy issues for an IoT based smart home provides a smart home IoT architecture that enables users to interact through various devices that support smart home management, and analyzes different scenarios to determine the user's possible security and privacy question. The literature Low-cost flow-based security solutions forsmart-home IoT devices provides a solution for future smart home network-level security, that is, flow-based monitoring not only achieves most of the security advantages of packet-based monitoring, but also reduces processing costs. cost. The document A Host-Based Intrusion Detection and Mitigation Framework for Smart Home IoT Using OpenFlow proposes an IoT intrusion detection and mitigation framework (IoT-IDM) to provide network-level protection for smart devices deployed in home environments. Mainly used to monitor the network activity of expected smart devices in the home environment and investigate for any suspicious or malicious activity. Although the above method protects the privacy of users to a certain extent, there are still some architectural problems. For example, the above-mentioned documents all adopt a central transaction data processing mechanism. If the central node is compromised, it is difficult to guarantee the security and privacy of device data.

SUMMARY OF THE INVENTION

The present invention provides a new method for data distribution and privacy protection of a smart home system. By combining homomorphic encryption and block chain technology, a more secure privacy guarantee is provided for data exchange between smart devices oriented to edge computing.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions:

A privacy protection method based on homomorphic encryption blockchain, including:

ST1: Build a smart home system model, the smart home system model is a quintuple:

(MT,HIG,SC,CT,α,β)

in:

(1) MT={mt _i |i∈N ⁺ } is a finite set of monitoring terminals, where mt _i represents the ith monitoring terminal;

(2) HIG={hig _i |i∈N ⁺ } is a finite set of home smart gateways, where hig _i represents the i-th home smart gateway, and multiple home smart gateways form a blockchain;

(3) SC={sc _i |i∈N ⁺ } is a finite set of perceptrons, where sc _i represents the ith perceptron;

为MT到HIG的通信网络；(4)

It is the communication network from MT to HIG;

为HIG到SC的通信网络；(5)

It is the communication network from HIG to SC;

Each home smart gateway is a node, and multiple home smart gateways form a blockchain;

ST2: Assign a pair of secret keys to each home smart gateway in the blockchain, the pair of secret keys includes a public key and a private key, and set a network-wide secret key at the same time, the network-wide secret key includes the network-wide public key and The whole network secret key;

ST3: Divide the entire network nodes in the blockchain into special nodes and ordinary nodes, and the special nodes store the public key of each home intelligent gateway;

ST4: Each home intelligent gateway receives and saves the information of the monitoring terminal collected by the sensor, and divides the information into visible information and invisible information. After the invisible information is homomorphically encrypted with the public key of the whole network, the visible information and The invisible information is packaged into a data package and signed with a private key, and the signed data package is sent to the network through the home smart gateway;

ST5: Perform network-wide verification on data packets;

ST6: The accounting node writes a new block to all verified data within a period of time, which is connected to the tail of the main blockchain.

The block data composition method of each block in the block chain is as follows:

Divide the information stored by each smart home gateway into visible information and invisible information;

Homomorphic encryption is performed on invisible information using the public key of the entire network to generate ciphertext;

The ciphertexts of multiple home smart gateways stored in the same block are stored in the block body for recording;

After the ciphertext hash operation of multiple smart home gateways stored in the same block, a unique root hash value is generated and stored in the block header. At the same time, the block header also stores the network-wide public key for homomorphic encryption of the ciphertext.

In the ST5, the network-wide verification of the data packet includes:

Each data packet is signed by the private key of the home intelligent gateway. The ordinary node determines to send the data packet to the home intelligent gateway of the network by querying the public key of each home intelligent gateway stored in the special node, and then the node sends the data to a valid home intelligent gateway. The trusted third-party service sends a homomorphic decryption request to verify the authenticity of the information. After receiving the request, the third-party service sends decrypted data for the requester according to the network-wide secret key for decryption.

In the ST6, after the transaction information is successfully verified, each home intelligent gateway selects the accounting node of the entire network according to the POW consensus algorithm, and the accounting node writes all the information within a period of time into a new block, which is linked in The tail end of the main blockchain.

A pair of secret keys is randomly assigned to each home smart gateway through a third-party trust organization, and the whole network secret key is randomly assigned through a third-party trust organization.

A system for applying the method, comprising:

A set of home smart gateways, each home smart gateway in the home smart gateway set is a node, and multiple home smart gateways form a blockchain;

A sensor set, each sensor in the sensor set can obtain monitoring information generated by the monitoring terminal and transmit it to the corresponding home intelligent gateway;

Monitoring terminal set, each monitoring terminal in the monitoring terminal set can generate monitoring information;

a processor capable of implementing the following methods:

(1) Allocate a pair of secret keys to each home intelligent gateway in the blockchain, the pair of secret keys includes a public key and a private key, and set up a network-wide secret key at the same time, and the network-wide secret key includes a network-wide public key and the whole network key;

(2) Divide the entire network nodes in the blockchain into special nodes and ordinary nodes, and the special nodes store the public key of each home intelligent gateway;

(3) Each home intelligent gateway receives and saves the information collected by the monitoring terminal, and divides the information into visible information and invisible information. After the invisible information is homomorphically encrypted by the public key of the whole network, the visible information and invisible information After the information is packaged into a data package, it is signed with a private key, and the signed data package is sent to the network through the home smart gateway;

(4) Verify the entire network of data packets;

(5) The accounting node writes a new block to all the verified data for a period of time, which is connected to the tail of the main blockchain.

Beneficial effects of the present invention: The present invention can provide a more secure privacy guarantee for data exchange between smart devices by implementing homomorphic encryption and distribution protection mechanism for sensitive data of users.

Description of drawings

Figure 1 is a schematic diagram of blockchain encryption.

Detailed ways

The present invention will be further described in detail below in conjunction with specific embodiments.

Blockchain is a technical solution in which any number of nodes collectively maintain a reliable database in a decentralized and trustless manner through cryptographic methods. The data structure of the blockchain is mainly divided into two parts: 1) the block header, which mainly contains the hash value of the previous block, which is used to connect the previous block to ensure the integrity of the blockchain; 2) the block The block body contains the main information of this block (such as transaction information), which together with the hash value of the previous block and the random number together constitute the hash value of this block. The data structure of the blockchain enables the information of each block on the chain to be traced back to the predecessor node and affects the information of the successor nodes. Its cryptography method ensures that malicious attacks cannot tamper with information, thereby ensuring the security and integrity of data. The construction of the blockchain follows a set of consensus and protocol mechanisms. Every node in the entire network can verify or write records, but only when most nodes (or even all nodes) in the entire network consistently confirm the correctness of a record, the corresponding data Only allowed to be written into the block.

The Paillier homomorphic encryption system is the first additive homomorphic encryption cryptosystem based on the problem of determining the composite residue class. It was proposed by the scholar Paillier in 1999. Its security is based on the problem of determining the composite residue. This mechanism supports any number of additions. Homomorphic operation. Its additive homomorphism can not only process ciphertext data quickly, but also meet high security requirements. This means that, given only the public key and the encryption of m1 and m2, the encryption of m1+m2 can be calculated.

The present invention provides a smart home data privacy protection method based on blockchain and homomorphic encryption. Therefore, the present invention first establishes a smart home system model, and the smart home system model is a quintuple SHS:

(MT,HIG,SC,CT,α,β)

in:

(1) MT={mt _i |i∈N ⁺ } is a finite set of monitoring terminals, where mt _i represents the ith monitoring terminal;

(2) HIG={hig _i |i∈N ⁺ } is a finite set of home smart gateways, where hig _i represents the i-th home smart gateway, and multiple home smart gateways form a blockchain;

(3) SC={sc _i |i∈N ⁺ } is a finite set of perceptrons, where sc _i represents the ith perceptron;

为MT到HIG的GSM/GPRS/Internet/WIFI通信网络；(4)

GSM/GPRS/Internet/WIFI communication network from MT to HIG;

为HIG到SC的ZigBee/Lora/Bluetooth/WIFI通信网络。(5)

ZigBee/Lora/Bluetooth/WIFI communication network from HIG to SC.

The smart home system model divides the whole framework into three layers: application layer, network layer and perception layer. Among them, the application layer mainly conducts data access, analysis and processing, and finally issues control commands, that is, the user can access the terminal through the GSM/GPRS/Internet/WIFI network; the network layer mainly involves network access and data transmission. Namely α and β; the perception layer mainly collects data generated by real-world devices. The home gateway is the control core of the smart home system. It is the only way to connect the external network and the home internal network, and plays a role in linking the previous and the next. Upward allows access to any device that can access the GSM/GPRS/Internet/WIFI network, and downwards collects communication data of various sensors through ZigBee/Lora/Bluetooth/WIFI network.

That is, the above monitoring terminal refers to various mobile devices in the real world, such as mobile phones, iPads, electricity meters, air conditioners and other devices. Perceptrons are sensing devices that mainly collect data generated by real-world devices.

The sensor collects the information generated by the monitoring terminal and transmits it to the home smart gateway. The smart gateway can be used as a node in the blockchain to form a blockchain. The monitoring terminal cannot connect to the smart gateway for data access, but is only a device that generates data.

In the blockchain, each home smart gateway is a node of the blockchain, and multiple home smart gateways can form a blockchain. At this time, on the basis of the above SHS model, the blockchain framework is introduced to give A smart home system PEB-SHS based on Paillier encrypted blockchain is developed.

The PEB-SHS model is an octet:

(MT,HIG,SC,K,pk _b ,α,φ,β)

Among them, the meanings of MT, HIG, SC, α, β are consistent with the SHS model, and K, pk _b , and φ are:

(1) K={pk _i |i∈N ⁺ } is a finite set of HIG public keys;

(2) pk _b is the public key for data encryption of the entire network;

(3) φ is the following P2A_PEBC algorithm for information storage between each HIG to ensure information security.

In the embodiment of the present invention, a block data structure PE-BDS based on Paillier encryption is provided to describe the data form in the PEB-SHS model. Because the transaction data in PE-BDS mainly records the user's health information, such as blood pressure BP, heart rate HR, oxygen content OC, respiratory rate RR, etc., and these data are data that need to be protected by privacy, so this data block will not be collected. The received information is directly hashed, but the plaintext information (PT1-PT4 in the figure) is first divided into visible information PVD and invisible information IPD. The former is some information that can be disclosed, and the latter is privacy, sensitive, Only user-visible information, such as BP, HR, RR, OC, etc. Then, use the whole network secret key Block-PK to perform Paillier homomorphic encryption on IPD, generate ciphertext (CT1-CT4 in the figure) and perform hash operation (Hash1-Hash4 in the figure), and finally generate a unique root hash The value is recorded in the block header, and the ciphertext is recorded in the block body.

In addition, compared with the original block chain, the block header part of the data model adds a piece of information pk _b , which mainly records the public key used in the Paillier encryption of the IPD in this block, so that the real information can be checked later. This method of encrypting first and then hashing enhances the protection of private data and can further prevent the leakage of private data.

Based on the above-mentioned smart home model and block data structure, the present invention provides a privacy protection method P2A_PEBC based on a homomorphic encryption block chain, and the method specifically includes the following steps:

Step 1: Assign key SHK and network-wide key BLOCK-PK: A pair of SHK is randomly assigned to each home smart gateway in the blockchain by a third-party trust organization, and each pair of keys contains a pair of public keys pk _i and the private key sk _i , and the whole network secret key is randomly generated by a third-party trust organization at the same time, and the whole network secret key BLOCK-PK includes the whole network public key pk _b and the whole network secret key sk _b ; in the implementation of the present invention For example, the above-mentioned third-party trust authority can choose VeriSign.

Step 2: Divide nodes: Divide the entire network nodes in the blockchain into special nodes SP and ordinary nodes NP. The special nodes store the public key of each home intelligent gateway; the number of special nodes is at least 4 according to the requirements of Byzantine consensus , which mainly stores K; ordinary nodes are mainly responsible for publishing and verifying data information in the network.

Step 3: Paillier encrypts the IPD type data. Each home intelligent gateway receives and saves the information collected by the sensor, and _divides the information into visible information and invisible information. The visible information is packaged into a data packet DP and signed by the private key _ski , and the signed data packet is sent to the network through the home intelligent gateway;

DP _d = {Data _ski |d∈N ⁺ ,i∈N ⁺ }

Among them, d is the serial number of the data packet, and Data _ski represents the data signed with the private key _ski . Finally, HIG publishes DP _d to the network through the router.

Step 4: The data packets obtained in the previous step are verified by the whole network node. First, the SP node authenticates the source of DP _d and maintains the public ledger. Since each DP _d has the _HIG 's ski signature on it, the NP can query the K stored in the SP to determine which HIG sent the DP _d . Then, the NP node sends a homomorphic decryption request to a trusted third-party service to verify the authenticity of the information. After receiving the request, the third-party service sends decrypted data to the requester according to sk _b .

Step 5: Get the blockchain public ledger and local ledger. After the transaction information is successfully verified, each HIG selects the accounting node of the entire network according to the POW consensus algorithm, and the accounting node writes all the information within a period of time into a new block, which is linked to the end of the main chain. The data structure of each block is the above-mentioned PE-BDS, and each block contains multiple node data.

The following table is the pseudo code of the above steps

In the PEB-SHS model, each SHS is equivalent to a peer peer in the blockchain. The sensor in the home detects its surrounding environment and sends the detected data to the ZigBee/Lora/Bluetooth/WIFI network. Intelligent gateway, each HIG processes the information according to the P2A-PEBC algorithm, and finally the accounting node stores the data into the blockchain.

The present invention also provides a system applying the method, the system includes a collection of home intelligent gateways, a collection of sensors, and a collection of monitoring terminals.

Each home intelligent gateway in the home intelligent gateway set is a node, and multiple home intelligent gateways form a blockchain; each sensor in the perceptron set can obtain information and transmit it to the corresponding home intelligent gateway; the monitoring terminal set Each monitoring terminal in the device can connect to the home intelligent gateway to obtain the information transmitted by the sensor.

The system of the present invention also includes a processor capable of implementing the software method of the present invention:

(1) Allocate a pair of secret keys to each home intelligent gateway in the blockchain, the pair of secret keys includes a public key and a private key, and set up a network-wide secret key at the same time, and the network-wide secret key includes a network-wide public key and the whole network key;

(2) Divide the entire network nodes in the blockchain into special nodes and ordinary nodes, and the special nodes store the public key of each home intelligent gateway;

(3) Each home intelligent gateway receives and saves the information collected by the monitoring terminal, and divides the information into visible information and invisible information. After the invisible information is homomorphically encrypted by the public key of the whole network, the visible information and invisible information After the information is packaged into a data package, it is signed with a private key, and the signed data package is sent to the network through the home smart gateway;

(4) Verify the entire network of data packets;

(5) The accounting node writes a new block to all the verified data for a period of time, which is connected to the tail of the main blockchain.

The above-mentioned processor is a processor in a broad sense, that is, the processor is a general term, not only refers to one processor, but may refer to a plurality of processors that jointly implement the above method of the present invention.

As an embodiment of the present invention, for a cell with 800 households, each user's heart rate (HR), blood pressure (BP), and respiratory rate (RR) are uploaded to the HIG when collecting information. The input values and results of this homomorphic calculation are saved as a PE-BDS block and synchronized to all HIGs. Users with HIG authority can view the statistical values of these health data through the authorized homomorphic public key at any time, and can also trace and accumulate historical data along the chain. However, since the signature of the private key is added during data preprocessing, any node It is impossible to spy on the private data of other nodes without obtaining the permission of the SP.

In the present invention, HIG performs Paillier encryption and private key signature on the collected local source data, and forwards it in the blockchain network in the form of ciphertext data packets. If the data is intercepted when passing through the router or during the transmission process, the external network attacker cannot obtain the HIG privacy information because it cannot pass the verification of the SP. For intranet attackers, such as HIGs captured by malicious programs, there are two cases: 1) If it is a general NP node, since the original HIG cannot be obtained, the private information cannot be obtained; 2) If it is an SP node, you must complete the consensus of the SP set before it can be obtained. According to the Byzantine consensus mechanism, the consensus needs to be supported by more than 2/3 of the nodes, which means that the attacker must capture 2/3 of the SP nodes to obtain it. From the probability This is almost impossible. Therefore, the method of the present invention can largely guarantee the security of data.

At the same time, the present invention uses the PE-BDS structure to organize blocks. Since the block chain technology itself has the characteristics of anti-tampering, permanence, decentralization and openness, each HIG can synchronize the chain blocks after forming blocks. This permanent database can be obtained in the way of PVD data, in which PVD data can be directly obtained and calculated from the chain block, and the CT data involving privacy can be counted and accumulated isomorphically calculated. After obtaining authorization, the corresponding results can be obtained without destroying the data set. privacy.

In addition, the various types of private data processed by the paillier algorithm are distinguished according to different families and different index items, and the encrypted result set is refined to the index level in terms of data granularity, which can be used by nodes that need to process and calculate according to the data. Subsets need to be selected, and statistical calculations can also be performed according to different purposes. Since ciphertext data does not involve personal privacy, sharing, copying and distributing data will not affect the disclosure of privacy.

And because of the use of blockchain technology as support, by distributing the workload to the network, when a node fails, other nodes will not be affected, avoiding a single point of failure. In addition, the decentralized storage, immutability, strong timing, and public verification of the blockchain allow each HIG to participate in the calculation and verification process of the entire system, which not only improves the computing power of the system, but also enhances the the robustness of the system.

In the description of this specification, the particular features, structures, materials or characteristics may be combined in any suitable manner in any one or more embodiments or examples.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the scope disclosed by the present invention should be Included in the protection scope of the present invention.

Claims (6)

1. A privacy protection method based on a homomorphic encryption block chain is characterized by comprising the following steps:

ST 1: establishing an intelligent home system model, wherein the intelligent home system model is a quintuple:

(MT,HIG,SC,CT,α,β)

wherein:

(1)MT＝{mt_i|i∈N⁺is a finite set of monitor terminals, where mt_iIndicating the ith monitoring terminal;

(2)HIG＝{hig_i|i∈N⁺is a familyA limited set of intelligent gateways, of which hig_iRepresenting the ith home intelligent gateway, wherein a plurality of home intelligent gateways form a block chain;

(3)SC＝{sc_i|i∈N⁺is a finite set of perceptrons, with sc_iRepresents the ith sensor;

(4)

a communication network for MT to HIG;

(5)

a HIG to SC communication network;

each home intelligent gateway is a node, and a plurality of home intelligent gateways form a block chain;

ST 2: distributing a pair of secret keys for each home intelligent gateway in a block chain, wherein the pair of secret keys comprises a public key and a private key, and meanwhile, setting a whole-network secret key, and the whole-network secret key comprises a whole-network public key and a whole-network secret key;

ST 3: dividing the whole network nodes in the block chain into special nodes and common nodes, wherein the special nodes store the public key of each home intelligent gateway;

ST 4: each home intelligent gateway receives and stores information of the monitoring terminal acquired by the sensor, divides the information into visible information and invisible information, homomorphically encrypts the invisible information through a whole network public key, packages the visible information and the invisible information into a data packet, signs the data packet through a private key, and sends the signed data packet to a network through the home intelligent gateway;

ST 5: carrying out whole network verification on the data packet;

ST 6: and the accounting node writes all verified data into a new block in a period of time and is connected to the tail part of the main block chain.

2. The privacy protection method based on the homomorphic encryption block chain according to claim 1, characterized in that:

the block data construction method of each block in the block chain comprises the following steps:

dividing information stored by each home intelligent gateway into visible information and invisible information;

homomorphic encryption is carried out on invisible information by using a whole network public key to generate a ciphertext;

the ciphertexts of the plurality of home intelligent gateways stored in the same block are stored in the block for recording;

and generating a unique root hash value after carrying out hash operation on the ciphertexts of the plurality of home intelligent gateways stored in the same block, storing the unique root hash value into a block head, and storing a full-network public key for homomorphic encryption on the ciphertexts in the block head at the same time.

3. The privacy protection method based on the homomorphic encryption block chain according to claim 1, characterized in that:

in ST5, the performing full network authentication on the packet includes:

each data packet is provided with a private key signature of the home intelligent gateway, the common node determines to send the data packet to the home intelligent gateway of the network by inquiring the public key of each home intelligent gateway stored in the special node, then the node sends a homomorphic decryption request to a credible third-party service to verify the authenticity of information, and the third-party service sends decryption data to a requester for decryption after receiving the request according to the whole network private key.

4. The privacy protection method based on the homomorphic encryption block chain according to claim 1, characterized in that:

in ST6, after the transaction information is successfully verified, each home intelligent gateway selects a billing node of the whole network according to the POW consensus algorithm, and the billing node writes all information in a period of time into a new block and links the new block to the tail end of the main block chain.

5. The privacy protection method based on the homomorphic encryption block chain according to claim 1, characterized in that:

and randomly distributing a pair of secret keys for each home intelligent gateway through a third-party trust mechanism, and simultaneously randomly distributing a whole network secret key through the third-party trust mechanism.

6. A system for applying the method of any of claims 1 to 5, comprising:

each home intelligent gateway in the home intelligent gateway set is a node, and a plurality of home intelligent gateways form a block chain;

each sensor in the sensor set can acquire monitoring information generated by the monitoring terminal and transmit the monitoring information to the corresponding home intelligent gateway;

the monitoring terminal set comprises monitoring terminals, wherein each monitoring terminal in the monitoring terminal set can generate monitoring information;

a processor capable of implementing the method of:

(1) distributing a pair of secret keys for each home intelligent gateway in a block chain, wherein the pair of secret keys comprises a public key and a private key, and meanwhile, setting a whole-network secret key, and the whole-network secret key comprises a whole-network public key and a whole-network secret key;

(2) dividing the whole network nodes in the block chain into special nodes and common nodes, wherein the special nodes store the public key of each home intelligent gateway;

(3) each home intelligent gateway receives and stores information collected by the monitoring terminal, divides the information into visible information and invisible information, homomorphically encrypts the invisible information through a whole network public key, packages the visible information and the invisible information into a data packet, signs the data packet through a private key, and sends the signed data packet to a network through the home intelligent gateway;

(4) carrying out whole network verification on the data packet;

(5) and the accounting node writes all verified data into a new block in a period of time and is connected to the tail part of the main block chain.

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