WO2020037654A1 - Blockchain data protection method, device and system, and computer-readable storage medium - Google Patents

Abstract

The present application provides a blockchain data protection method, device and system, and a computer-readable storage medium, wherein same are applied in the technical field of blockchain. The method comprises: a first blockchain node performing homomorphic encryption on data to be encrypted so as to obtain encrypted ciphertext; the first blockchain node uploading a request for computing the encrypted ciphertext to a blockchain system; a second blockchain node acquiring the request from the blockchain system; the second blockchain node acquiring the encrypted ciphertext according to the request; and the second blockchain node computing the acquired encrypted ciphertext, and uploading a computation result to the blockchain system. The embodiments of the present application can protect blockchain data and improve the efficiency of the computation and processing of the blockchain data.

Description

Blockchain data protection method, device, system and computer-readable storage medium Technical field

This application relates to the field of blockchain technology, and in particular, this application relates to a method, device, system, and computer-readable storage medium for protecting blockchain data.

Background technique

In the past 20 years, we have witnessed the rapid development of the Internet, which has brought us great convenience in life. However, Internet applications are becoming more and more centralized, and resources are mostly controlled by large enterprises (such as Google, Facebook, Twitter, etc.). In order to use these applications, users must give their private information to corporate management and give them full trust. The current Internet is flooded with identity theft, spam, advertising, hacking, and more.

Blockchain technologies such as Bitcoin and Ethereum provide the foundation for building a completely decentralized Internet application. The underlying technology of the blockchain builds a decentralized and trusted distributed network, all nodes maintain a shared database ledger, and all records are traceable and cannot be changed.

However, there are still many problems to be solved by using blockchain to construct a large-scale Internet application. Modern Internet applications often require a lot of analysis and calculations on users' private data. The publicly traceable and verifiable attributes of the blockchain cause the data on the current blockchain to be publicly visible (such as Bitcoin, all transaction records can be checked). If users upload private data to the blockchain, then All nodes are visible. In addition, the blockchain is not suitable for calculation-intensive applications. The computing resources on the blockchain are mainly used to record changes in database ledgers, transaction verification, and reach consensus, etc., and are not suitable for analysis on large amounts of data.

Therefore, in order to be able to build more modern Internet applications on the blockchain, the issues of blockchain data privacy and computing efficiency need to be addressed.

Summary of the Invention

In view of the shortcomings of the existing methods, this application proposes a method, a device, a system, and a computer-readable storage medium for protecting blockchain data to protect the blockchain data and improve the efficiency of the calculation and processing of the blockchain data.

Embodiments of the present application provide a method for protecting blockchain data according to a first aspect, including:

The first blockchain node performs homomorphic encryption on the encrypted data to obtain the encrypted ciphertext;

Uploading, by the first blockchain node, a request for computing the encrypted ciphertext to a blockchain system;

The second blockchain node obtains the request from the blockchain system;

Obtaining, by the second blockchain node, the encrypted ciphertext according to the request;

The second blockchain node calculates the obtained encrypted ciphertext, and uploads the calculation result to the blockchain system.

According to the second aspect, the embodiments of the present application also provide another method for protecting blockchain data, including:

Homomorphically encrypt encrypted data to obtain encrypted ciphertext;

Upload a request to calculate the encrypted ciphertext to a blockchain system, so that other blockchain nodes in the blockchain system can calculate the encrypted ciphertext when receiving the request.

According to the third aspect, the embodiments of the present application also provide another method for protecting blockchain data, including:

Obtaining a request for calculating an encrypted ciphertext uploaded by a first blockchain node from a blockchain system; the encrypted ciphertext is obtained by homomorphic encryption of data to be encrypted;

Obtaining the encrypted ciphertext according to the request;

Calculate the obtained encrypted ciphertext;

The calculation results are uploaded to the blockchain system.

The embodiment of the present application further provides a blockchain data protection system according to the fourth aspect, including a first blockchain node and a second blockchain node;

The first blockchain node is configured to perform homomorphic encryption on the encrypted data to obtain an encrypted ciphertext; upload a request for calculating the encrypted ciphertext to a blockchain system;

The second blockchain node is configured to obtain the request from the blockchain system; obtain the encrypted ciphertext according to the request; calculate the obtained encrypted ciphertext, and upload the calculation result to the area Blockchain system.

The embodiment of the present application further provides a blockchain data protection device according to a fifth aspect, including:

An encryption module for homomorphically encrypting the encrypted data to obtain encrypted cipher text;

A request uploading module is configured to upload a request for calculating the encrypted ciphertext to a blockchain system, so that other blockchain nodes in the blockchain system perform the encryption ciphertext upon receiving the request. Calculation.

According to a sixth aspect, the embodiments of the present application further provide another blockchain data protection device, including:

A request obtaining module, configured to obtain a request for calculating an encrypted ciphertext uploaded by a first blockchain node from a blockchain system; the encrypted ciphertext is obtained by homomorphic encryption of data to be encrypted;

An encrypted ciphertext obtaining module, configured to obtain the encrypted ciphertext according to the request;

A calculation module for calculating the obtained encrypted ciphertext;

An uploading module is configured to upload the calculation result to the blockchain system.

According to a seventh aspect, the embodiments of the present application further provide a computer-readable storage medium on which a computer program is stored, and when the program is executed by a processor, the method for protecting a blockchain data according to any one of the foregoing is implemented. .

The foregoing blockchain data protection method, device, system, and computer-readable storage medium perform homomorphic encryption on encrypted data, and uploads the obtained encrypted ciphertext to the blockchain system, thereby protecting the security of the blockchain data. ; Homomorphic encryption supports multiple operations (addition, multiplication) and high computational efficiency. Therefore, by introducing efficient homomorphic encryption with more abundant computing operation types, the efficiency of blockchain data calculation processing is improved.

Additional aspects and advantages of the present application will be given in the following description, which will become apparent from the following description or be learned through the practice of the present application.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and / or additional aspects and advantages of this application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic structural diagram of a communication system applicable to a blockchain data protection method according to an embodiment of the present application;

2 is a schematic diagram of a blockchain data protection method according to an embodiment of the present application;

3 is a schematic diagram of a blockchain data protection method according to an embodiment of the present application;

4 is a schematic diagram of a blockchain data protection system according to an embodiment of the present application;

5 is a schematic diagram of a blockchain data protection method according to another embodiment of the present application;

6 is a schematic diagram of a blockchain data protection device according to an embodiment of the present application;

7 is a schematic diagram of a blockchain data protection method according to another embodiment of the present application;

8 is a schematic diagram of a blockchain data protection device according to another embodiment of the present application;

FIG. 9 is a schematic diagram of a server according to an embodiment of the present application.

detailed description

Hereinafter, embodiments of the present application will be described in detail. Examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals indicate the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present application, and cannot be construed as limiting the present application.

Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms "a", "an", "the" and "the" may include plural forms. It should be further understood that the word "comprising" used in the specification of this application refers to the presence of the described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, Integers, steps, operations, elements, components, and / or groups thereof.

It is understood that the terms "first", "second", and the like used in this application can be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element. For example, without departing from the scope of this application, a first blockchain node may be referred to as a second blockchain node, and similarly, a second blockchain node may be referred to as a first block Chain node. Both the first blockchain node and the second blockchain node are blockchain nodes, but they are not the same blockchain node.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms such as those defined in the general dictionary should be understood to have meanings consistent with the meanings in the context of the prior art, and unless specifically defined like this, they would not be idealized or overly Formal meaning to explain.

The blockchain data protection method provided in this application can be applied to the communication system shown in FIG. 1. As shown in FIG. 1, the communication system includes: a blockchain network, a first blockchain node 11 and a second blockchain node 12. This is for illustrative purposes only, and does not limit the specific number of blockchain nodes. It also does not limit the types of blockchain nodes. Blockchain nodes can specifically be smartphones, tablets, laptops, etc., and combinations thereof. The first blockchain node 11 is used to encrypt the data to be encrypted and upload a calculation request to the blockchain system, and the second blockchain node 12 is used to obtain the request and calculate the encrypted ciphertext performed in the request.

First, from the perspective of the entire system, the method and system for protecting blockchain data in this application will be described in detail.

As shown in FIG. 2, in one embodiment, a method for protecting blockchain data includes:

S21. The first blockchain node performs homomorphic encryption on the encrypted data to obtain encrypted ciphertext.

Blockchain is a new application model of computer technology such as distributed data storage, point-to-point transmission, consensus mechanism, and encryption algorithms. The so-called consensus mechanism is a mathematical algorithm for establishing trust and obtaining rights between different nodes in a blockchain system. Blockchain nodes refer to computers in the blockchain network, including mobile phones, miners, desktops, servers, etc. The person who operates a blockchain node can be an ordinary wallet user, a miner, and multiple people, etc. .

Privacy protection is a popular direction on the blockchain, including ZCash (big zero coin), Monero (monero), Dash (dash), and XVG (cryptographic currency Verge). Among them, ZkSnark (zero-knowledge, non-interactive, interactive, and simple knowledge under zero knowledge) used by ZCash uses zero-knowledge proofs and other hidden transaction information. At present, the development of applications based on the blockchain platform also pays more and more attention to the privacy protection of user data, among which homomorphic encryption plays an important role.

Homomorphic encryption is a special kind of encryption that allows calculations (addition, multiplication) to be performed directly on the ciphertext, and after decryption, the result corresponding to the plaintext calculation is obtained. Homomorphic encryption is divided into full homomorphic encryption (supporting both addition and multiplication) and partial homomorphic encryption (addition or multiplication), which is an important research direction of current cryptography. Especially in terms of full homomorphic encryption, it has a wide range of application scenarios in terms of user privacy protection, such as implementing searchable encryption, and cloud platforms analyzing user encrypted data. The first fully homomorphic encryption scheme was based on lattice ciphers, which was proposed by Craig Gentry in 2009, and has led to a boom in research in this direction.

Homomorphic encryption can use the existing encryption methods in the prior art, and it will be described below with reference to two examples.

For example, Nebula Genomics is committed to using blockchain technology to promote the research and development of genetic analysis. Eliminate middlemen in the gene market, so that users can control the buying and selling of their own genetic data, and scientific research institutions such as hospitals and universities can also purchase genetic data directly from individuals. In this process, users are inevitably required to send genetic data to the buyer, and the buyer then performs calculation analysis on the data. In order to protect the privacy of users, Nebula Genomics uses Intel Software Guard Extensions (SGX, Intel Software Protection Extensions) and some homomorphic encryption (addition), as shown in Figure 3.

Enigma provides a more extensive privacy-protected computing platform. Applicable to secure multi-party computing, users can split the data to be processed into multiple copies and distribute them to different nodes for calculation, further improving the calculation processing speed. In addition, SPDZ is used to prevent attacks by malicious nodes and perform related homomorphic encryption operations on ciphertext.

However, the applicant of this application has found through research that these applications are currently limited by the efficiency of homomorphic encryption calculations. For example, Nebula can only use homomorphic encryption to process the data first, and the calculation-intensive tasks are still performed in SGX after decryption. The homomorphism calculation in Enigma also mainly adds homomorphism. Multiplication of homomorphism requires the construction of a triplet <a, b, c> that satisfies c = ab, then s = s1 * s2 can be calculated as follows:

s = c + e * b + f * a + e * f

e = s1-a, f = s2-b.

The construction of the triplet requires a lot of calculations, and SPDZ anti-malicious nodes also need to perform data re-splitting, which increases the communication overhead.

Therefore, to support true homomorphic encryption computing on the blockchain and protect user privacy, further optimization of computing efficiency is needed. In order to more conveniently support the use of homomorphic encryption on the blockchain, the homomorphic encryption algorithm selected and designed needs to support multiple operations (addition, multiplication) and high computational efficiency. In one embodiment, the first blockchain node performs homomorphic encryption on the encrypted data to obtain encrypted ciphertext, including: the first blockchain node performs homomorphism on the encrypted data through a multi-key privacy protection outsourcing computing algorithm. Encrypt to get encrypted ciphertext. Multi-key privacy protection outsourcing calculation algorithms support addition (SAD), multiplication (SMD), and even division (SDIV) over integers, solving the greatest common factor (SGCD), maximum and minimum filtering (SMMS), and more.

The blockchain platform integrates the addition and multiplication in the multi-key privacy protection outsourcing calculation algorithm, which can already meet almost all application requirements, such as counting employee salaries, performing machine neural network learning on user data samples, and other operations. Two operations are derived. In order to better understand the algorithm, we will use add homomorphism and multiplication homomorphism for illustration.

In one embodiment, the first blockchain node performs homomorphic encryption on the encrypted data by using a multi-key privacy protection outsourcing computing algorithm to obtain encrypted ciphertext, including:

S211. The first blockchain node splits the data to be encrypted into a first part and a second part.

There are many ways to split the data to be encrypted into two parts. For example, the data to be encrypted is split into two parts in order from front to back. For example, each data in the data to be encrypted is classified according to attributes. There are two classes, each class is a part, and so on.

S212. The first blockchain node encrypts the sum of the first part and the first random number by a set first public key to obtain a first encrypted data; and the second public key sets the second public key. The sum of the partial and second random numbers is encrypted to obtain second encrypted data.

This step is expressed as a formula:

X = [x] _pka * [r _a ] _pka = [x + r _a ] _pka , Y = [y] _pkb * [r _b ] _pkb = [y + r _b ] _pkb

Wherein, X is a first encrypted data, _pka of the first public key, x is a first portion, r _a is a first random number, [] _pka a first public key pair [] is the number of encrypted, _pkb second Public key, y is the second part, r _b is the second random number, and [] _pkb is the second public key to encrypt the number in [].

S213: The first blockchain node decrypts the first encrypted data by using a preset first decryption algorithm and a set first private key to obtain the first decrypted data; and using the first decryption algorithm and the The first private key decrypts the second encrypted data to obtain second decrypted data.

This step is expressed as a formula:

X '= PDO _SK ⁽¹⁾ (X), Y' = PDO _SK ⁽¹⁾ (Y)

Among them, X ′ is the first decrypted data, PDO is the first decrypted algorithm, _SK ⁽¹⁾ is the first private key, and Y ′ is the second decrypted data.

S214. The first blockchain node decrypts the first encrypted data and the first decrypted data by using a preset second decryption algorithm and a set second private key to obtain third decrypted data. The second decryption algorithm and the second private key decrypt the second encrypted data and the second decrypted data to obtain fourth decrypted data.

This step is expressed as a formula:

X ”= PDT _SK ⁽²⁾ (X; X '), Y” = PDT _SK ⁽²⁾ (Y; Y')

Among them, X "is the third decrypted data, Y" is the fourth decrypted data, PDT is the second decryption algorithm, and _SK ⁽²⁾ is the second private key.

S215. The first blockchain node encrypts the difference between the first sum value and the second sum value through a third public key to obtain an encrypted ciphertext of the data to be encrypted; the first sum value is the A sum of the third decrypted data and the fourth decrypted data, and the second sum value is a sum of the first random number and the second random number.

This step is expressed as a formula:

S = X ”+ Y”, R = r _a + r _b

Then, [S] _pkc · ([R] _pkc ) ^N-1 = [SR] _pkc = [x + y] _pkc

Among them, S is the first sum value, R is the second sum value, _pkc is the third public key, and N is the size of the integer field.

The ordinary homomorphic addition encryption algorithm only supports the calculation on the ciphertext encrypted under the same key, and SAD in this algorithm, given the ciphertext encrypted by different keys, [x] pka, [x] pkb, and the introduction The random numbers r _a and r _b can also obtain the ciphertext corresponding to the plaintext addition.

In another embodiment, the first blockchain node performs homomorphic encryption on the encrypted data by using a multi-key privacy protection outsourcing computing algorithm to obtain encrypted ciphertext, including:

S21a. The first blockchain node splits the data to be encrypted into a first part and a second part.

There are many ways to split the data to be encrypted into two parts. For example, the data to be encrypted is split into two parts in order from front to back. For example, each data in the data to be encrypted is classified according to attributes. There are two classes, each class is a part, and so on.

S21b. The first blockchain node encrypts the first part and the first random number through a set first public key, and multiplies the two values obtained after encryption to obtain the first encrypted data. Encrypts the second part and the second random number with the second public key, and multiplies the two values obtained after encryption to obtain the second encrypted data; Encrypt the difference between the product of the second random number and the first part to obtain third encrypted data; use the second public key to pair the fourth random number with the product of the first random number and the second part The difference is encrypted, and the fourth encrypted data is obtained.

This step is expressed as a formula:

X = [x] _pka * [r _x ] _pka , Y = [y] _pkb * [r _y ] _pkb

S = [R _x ] _pka · ([x] _pka ) ^Nr _y = [R _x -r _y · x] _pka

T = [R _y ] _pkb · ([y] _pkb ) ^Nr _x = [R _y -r _x · y] _pkb

Among them, X is the first encrypted data, Y is the second encrypted data, S is the third encrypted data, T is the fourth encrypted data, _pka is the first public key, and [] _pka is the first public key pair []. Data is encrypted, x is the first part, r _x is the first random number, y is the second part, r _y is the second random number, [] _pkb is the data in [] encrypted by the second public key, _pkb is the second public key, R _x is the third random number, and R _y is the fourth random number.

S21c. The first blockchain node decrypts the first encrypted data by using a preset first decryption algorithm and a set first private key to obtain first decrypted data. The first private key decrypts the second encrypted data to obtain second decrypted data; and decrypts the third encrypted data through the first decryption algorithm and the first private key to obtain third decrypted data ; Decrypting the fourth encrypted data by using the first decryption algorithm and the first private key to obtain fourth decrypted data.

This step is expressed as a formula:

X ₁ = PDO _SK ⁽¹⁾ (X), Y ₁ = PDO _SK ⁽¹⁾ (Y) S ₁ = PDO _SK ⁽¹⁾ (S), T ₁ = PDO _SK ⁽¹⁾ (T)

Among them, PDO is the first decryption algorithm, _SK ⁽¹⁾ is the first private key, and X ₁ , Y ₁ , S ₁ , and T ₁ are the first decrypted data, the second decrypted data, the third decrypted data, and the fourth decrypted in this order. data.

S21d. The first blockchain node decrypts the first decrypted data and the first encrypted data by using a preset second decryption algorithm and a set second private key, and using the second decryption algorithm and Decrypting the second decrypted data and the first encrypted data by the second private key, and multiplying the two values obtained after the decryption to obtain fifth decrypted data; by the second decryption algorithm and the The second private key decrypts the third decrypted data and the third encrypted data to obtain a sixth decrypted data; the fourth decrypted data and all the encrypted data are obtained through the second decryption algorithm and the second private key. Decrypt the fourth encrypted data to obtain the seventh decrypted data.

This step is expressed as a formula:

h = PDT _SK ⁽²⁾ (X1; X) · PDT _SK ⁽²⁾ (Y1; X),

S2 = PDT _SK ⁽²⁾ (S1; S), T2 = PDT _SK ⁽²⁾ (T1; T).

Among them, h is the fifth decrypted data, PDT is the second decrypted algorithm, _SK ⁽²⁾ is the second private key, S2 is the sixth decrypted data, and T2 is the seventh decrypted data.

S21e. The first blockchain node encrypts the fifth decrypted data, the sixth decrypted data, and the seventh decrypted data by using a set third public key to obtain the fifth encrypted data and the sixth Encrypted data and seventh encrypted data; encrypting a product of the first random number and the second random number with the third public key, and calculating the (N-1) th power of the value obtained after the encryption, Obtain the eighth encrypted data; encrypt the third random number by the third public key, and calculate the (N-1) -th power of the encrypted value to obtain the ninth encrypted data; pass the third The public key encrypts the fourth random number, and calculates the (N-1) -th power of the value obtained after encryption to obtain tenth encrypted data; N represents the size of the integer field.

This step is expressed as a formula:

H = [h] _pkc , S3 = [S2] _pkc , T3 = [T2] _pkc

S4 = ([r _x · r _y ] _pkc ) ^N-1 , S5 = ([Rx] _pkc ) ^N-1 , S6 = ([Ry] _pkc ) ^N-1 ,

Wherein, H, S3, T3, S4, S5, and S6 are the fifth decrypted data, the sixth decrypted data, the seventh decrypted data, the eighth encrypted data, the ninth encrypted data, and In the tenth encrypted data, pkc is a third public key, and N represents a size of an integer domain.

S21f. The first blockchain node sends the fifth encrypted data, the sixth encrypted data, the seventh encrypted data, the eighth encrypted data, the ninth encrypted data, and the tenth Multiply the encrypted data to obtain the encrypted ciphertext of the data to be encrypted.

This step is expressed as a formula:

H · T3 · S3 · S4 · S5 · S6 = [(h + (Rx-ry · x) + (Ry-rx · y) -rx · ry-Rx-Ry)] pkc = [x · y] _pkc

The multiplication homomorphism (SMD) given the ciphertexts [x] pka, [x] pkb, and random numbers rx, ry encrypted with different keys can also obtain the ciphertext corresponding to the plaintext multiplication.

After testing 1024bit (bit) integer, 80bit security level, 8-core 3.6GHZ (gigahertz) PC (personal computer), the time consumption of SAD is about 185ms, and the efficiency of SMD is 480ms, which greatly improves the area. Blockchain data calculation efficiency.

Therefore, the multi-key privacy protection outsourced computing algorithm can not only realize the encryption of the data to be encrypted, but also has higher computational efficiency than other homomorphic encryption algorithms. The data to be encrypted is data that needs to be protected, such as transaction data. Using multi-key privacy protection outsourcing computing algorithm to encrypt the encrypted data, the encrypted ciphertext can be obtained.

S22. The first blockchain node uploads a request for computing the encrypted ciphertext to a blockchain system.

The request for calculating the encrypted cipher text may be specifically determined according to service requirements, such as calculating an average value or a variance of the encrypted cipher text. The first blockchain node can upload a request to calculate encrypted ciphertext through a smart contract or op_return. Smart contract is a computer protocol designed to spread, verify or execute contracts in an information-based manner. Smart contracts allow trusted transactions to be performed without a third party. These transactions are traceable and irreversible. OP_RETURN can realize the broadcasting and recording of data in the blockchain, omitting the calculation steps, thus achieving the purpose of saving time and computing power.

In one embodiment, the uploading, by the first blockchain node to the blockchain system, a request to calculate the encrypted ciphertext includes:

S221. The first blockchain node uploads the encrypted ciphertext to a distributed file system, and obtains a file hash value of the encrypted ciphertext.

Distributed file system (Distributed File System) refers to the physical storage resources managed by the file system are not necessarily directly connected to the local node, but connected to the node through a computer network. In order to be more suitable for blockchain application development, optionally, the distributed file system may be an IPFS file system (InterPlanetary File System, Interstellar File System). IPFS is a peer-to-peer distributed file system. It attempts to connect the same file system for all computing devices (IPFS miners).

The first blockchain node uploads the encrypted ciphertext to the distributed file system. The file hash value (file hash) can be calculated before uploading the encrypted ciphertext, or the hash value of the file can be returned when uploading IPFS.

S222. The first blockchain node stores a correspondence between the file hash value and the encrypted cipher text in the distributed file system into a pre-created distributed hash table.

The first blockchain node creates a distributed hash-table (DHT, distributed hash table) in advance, and the DHT is accessed through the blockchain (Ethereum smart contract or Bitcoin op_return, etc.). DHT stores file hash indexes. Other blockchain nodes can obtain specific encrypted cipher text in the distributed file system through hash indexes.

S223. The first blockchain node uploads a request for calculating the encrypted ciphertext to a blockchain system; the request includes a file hash value of the encrypted ciphertext.

In order to facilitate other blockchain nodes to find the encrypted ciphertext to be calculated, the request for calculating the encrypted ciphertext uploaded by the first blockchain node may include the file hash value of the encrypted ciphertext.

S23. The second blockchain node obtains the request from the blockchain system.

After the first blockchain node uploads a request to calculate the encrypted ciphertext to the blockchain system, the second blockchain node can obtain the request from the blockchain system. If the request includes a file hash value of the encrypted ciphertext, the second blockchain node obtains the file hash value of the encrypted ciphertext.

S24. The second blockchain node obtains the encrypted ciphertext according to the request.

The second blockchain node needs to obtain the corresponding encrypted ciphertext according to the request for calculation. In one embodiment, the obtaining, by the second blockchain node, the encrypted ciphertext according to the request includes:

S241. The second blockchain node accesses the distributed hash table through the blockchain system.

The distributed hash table stores the correspondence between the file hash value and the encrypted cipher text in the distributed file system. The second blockchain node needs to access the distributed hash table through the blockchain system.

S242. The second blockchain node searches the distributed file system for the encrypted ciphertext corresponding to the file hash value in the request according to the distributed hash table.

The request contains a file hash value. According to the distributed hash table, the encrypted cipher text in the distributed file system corresponding to the file hash value can be determined, and then the encrypted cipher text is obtained from the distributed file system.

S25. The second blockchain node calculates the obtained encrypted ciphertext, and uploads the calculation result to the blockchain system.

After the encrypted ciphertext is obtained, the second blockchain node can directly perform calculations on the encrypted ciphertext, such as averaging or variance, to obtain the calculation result, and upload the calculation result to the blockchain system. Since the multi-key privacy protection outsourcing calculation algorithm is adopted, not only the encryption of the blockchain data is realized, but also the efficiency of the calculation of the blockchain data is improved.

In one embodiment, the second blockchain node calculates the obtained encrypted ciphertext, uploads the calculation result to the blockchain system, and then further includes: the blockchain system verifies the calculation. When the result is valid, a token reward is issued to the second blockchain node. The blockchain system verifies whether the calculation result uploaded by the second blockchain node is accurate. If it is accurate, it will issue token rewards to the second blockchain node that calculates accurately, such as a certain amount of bitcoin, etc. No token reward will be issued to the second blockchain node that uploads the calculation results.

Based on the same inventive concept, the present application also provides a blockchain data protection system, including a first blockchain node 41 and a second blockchain node 42;

The first blockchain node 41 is configured to perform homomorphic encryption on the encrypted data to obtain an encrypted ciphertext; upload a request for computing the encrypted ciphertext to a blockchain system;

The second blockchain node 42 is configured to obtain the request from the blockchain system; obtain the encrypted ciphertext according to the request; perform calculation on the obtained encrypted ciphertext, and upload the calculation result to the Blockchain system.

In one embodiment, the first blockchain node 41 performs homomorphic encryption on the encrypted data by using a multi-key privacy protection outsourcing computing algorithm to obtain encrypted ciphertext.

In one embodiment, the first blockchain node 41 obtains the encrypted ciphertext through the following operations:

The first blockchain node splits the data to be encrypted into a first part and a second part;

The first blockchain node encrypts the sum of the first part and the first random number by a set first public key to obtain the first encrypted data; and sets the second part and the second part by a set second public key. Encrypt the sum of the second random number to obtain second encrypted data;

The first blockchain node decrypts the first encrypted data by using a preset first decryption algorithm and a set first private key to obtain first decrypted data; and using the first decryption algorithm and the first A private key decrypting the second encrypted data to obtain second decrypted data;

The first blockchain node decrypts the first encrypted data and the first decrypted data by using a preset second decryption algorithm and a set second private key to obtain third decrypted data; through the first Two decryption algorithms and the second private key decrypt the second encrypted data and the second decrypted data to obtain fourth decrypted data;

The first blockchain node encrypts the difference between the first sum value and the second sum value through a third public key to obtain an encrypted ciphertext of the data to be encrypted; the first sum value is the third The sum of the decrypted data and the fourth decrypted data, and the second sum is a sum of the first random number and the second random number.

In another embodiment, the first blockchain node 41 obtains the encrypted ciphertext through the following operations:

The first blockchain node splits the data to be encrypted into a first part and a second part;

The first blockchain node encrypts the first part and the first random number respectively through a first public key that is set, and multiplies the two values obtained after encryption to obtain the first encrypted data. Two public keys respectively encrypt the second part and the second random number, and multiply the two values obtained after encryption to obtain the second encrypted data; the third random number and the third random number are obtained by the first public key Encrypt the difference between the second random number and the first partial product to obtain third encrypted data; perform the difference between the fourth random number and the first random number and the second partial product by using the second public key; Encrypt to obtain the fourth encrypted data;

The first blockchain node decrypts the first encrypted data by using a preset first decryption algorithm and a set first private key to obtain first decrypted data; and using the first decryption algorithm and the first A private key decrypts the second encrypted data to obtain second decrypted data; decrypts the third encrypted data through the first decryption algorithm and the first private key to obtain third decrypted data; Decrypting the fourth encrypted data by the first decryption algorithm and the first private key to obtain fourth decrypted data;

The first blockchain node decrypts the first decrypted data and the first encrypted data by using a preset second decryption algorithm and a set second private key, and by using the second decryption algorithm and the The second private key decrypts the second decrypted data and the first encrypted data, and multiplies the two values obtained after decryption to obtain a fifth decrypted data; the second decryption algorithm and the second decrypted data are obtained. A private key decrypts the third decrypted data and the third encrypted data to obtain a sixth decrypted data; the fourth decrypted data and the first decrypted data are obtained through the second decryption algorithm and the second private key. Four encrypted data are decrypted to obtain seventh decrypted data;

The first blockchain node encrypts the fifth decrypted data, the sixth decrypted data, and the seventh decrypted data by using a set third public key to obtain the fifth encrypted data and the sixth encrypted data. And the seventh encrypted data; encrypt the product of the first random number and the second random number with the third public key, and calculate the (N-1) -th power of the value obtained after encryption to obtain the first Eight encrypted data; the third random number is encrypted by the third public key, and the (N-1) -th power of the value obtained after the encryption is calculated, to obtain the ninth encrypted data; by the third public key Encrypt the fourth random number, and calculate the (N-1) th power of the value obtained after encryption to obtain tenth encrypted data; N represents the size of the integer field;

The first blockchain node sends the fifth encrypted data, the sixth encrypted data, the seventh encrypted data, the eighth encrypted data, the ninth encrypted data, and the tenth encrypted data. Multiply to obtain the encrypted ciphertext of the data to be encrypted.

In one embodiment, the first blockchain node 41 uploads the encrypted ciphertext to a distributed file system, and obtains a file hash value of the encrypted ciphertext; The correspondence between the encrypted ciphertext in the distributed file system is stored in a pre-created distributed hash table; a request to calculate the encrypted ciphertext is uploaded to a blockchain system; the request includes the encrypted ciphertext File hash.

In one embodiment, the second blockchain node 42 accesses the distributed hash table through the blockchain system; according to the distributed hash table, looks up all the addresses in the distributed file system. The encrypted ciphertext corresponding to the file hash value in the request.

In one embodiment, when the blockchain system verifies that the calculation result is valid, a token reward is issued to the second blockchain node. The blockchain system verifies whether the calculation result uploaded by the second blockchain node is accurate. If it is accurate, it will issue token rewards to the second blockchain node that calculates accurately, such as a certain amount of bitcoin, etc. No token reward will be issued to the second blockchain node that uploads the calculation results.

Other technical features of the above-mentioned blockchain data protection system are the same as those of the above-mentioned blockchain protection method, and will not be repeated here.

In the following, from the perspective of the first blockchain node, the specific implementations of the blockchain data protection method and device of this application are described in detail.

As shown in FIG. 5, in one embodiment, a method for protecting blockchain data includes:

S51. Perform homomorphic encryption on the encrypted data to obtain an encrypted ciphertext.

Blockchain is a new application model of computer technology such as distributed data storage, point-to-point transmission, consensus mechanism, and encryption algorithms. The so-called consensus mechanism is a mathematical algorithm for establishing trust and obtaining rights between different nodes in a blockchain system. Blockchain nodes refer to computers in the blockchain network, including mobile phones, miners, desktops, servers, etc. The person who operates a blockchain node can be an ordinary wallet user, a miner, and multiple people, etc. .

Homomorphic encryption is a special kind of encryption that allows calculations (addition, multiplication) to be performed directly on the ciphertext, and after decryption, the result corresponding to the plaintext calculation is obtained. Homomorphic encryption is further divided into full homomorphic encryption (supporting both addition and multiplication) and partial homomorphic encryption (addition or multiplication), which is an important research direction of current cryptography. Especially in terms of full homomorphic encryption, it has a wide range of application scenarios in terms of user privacy protection, such as implementing searchable encryption, and cloud platforms analyzing user encrypted data.

However, there are efficiency problems with ordinary homomorphic encryption calculations. To support true homomorphic encryption computing on the blockchain and protect user privacy, further optimization of computing efficiency is needed.

In order to more conveniently support the use of homomorphic encryption on the blockchain, the homomorphic encryption algorithm selected and designed needs to support multiple operations (addition, multiplication) and high computational efficiency. In one embodiment, performing homomorphic encryption on the encrypted data to obtain the encrypted ciphertext includes: performing homomorphic encryption on the encrypted data through a multi-key privacy protection outsourcing computing algorithm to obtain the encrypted ciphertext. Multi-key privacy protection outsourcing calculation algorithms support addition (SAD), multiplication (SMD), and even division (SDIV) over integers, solving the greatest common factor (SGCD), maximum and minimum filtering (SMMS), and more.

The blockchain platform will integrate the addition and multiplication in the multi-key privacy protection outsourcing calculation algorithm. This can already meet almost all application requirements, such as counting employee salaries, performing machine neural network learning on user data samples, etc. Other operations can Derived on these two operations. In order to better understand the algorithm, we will use add homomorphism and multiplication homomorphism for illustration.

In one embodiment, the encrypted data is homomorphically encrypted by using a multi-key privacy protection outsourcing computing algorithm to obtain encrypted cipher text, including:

S511. Split the data to be encrypted into a first part and a second part.

There are many ways to split the data to be encrypted into two parts. For example, the data to be encrypted is split into two parts in order from front to back. For example, each data in the data to be encrypted is classified according to attributes. There are two classes, each class is a part, and so on.

S512. Encrypt the sum of the first part and the first random number by using the set first public key to obtain the first encrypted data; sum the sum of the second part and the second random number by using the set second public key. Encrypt to obtain the second encrypted data.

This step is expressed as a formula:

X = [x] _pka * [r _a ] _pka = [x + r _a ] _pka , Y = [y] _pkb * [r _b ] _pkb = [y + r _b ] _pkb

Wherein, X is a first encrypted data, _pka of the first public key, x is a first portion, r _a is a first random number, [] _pka a first public key pair [] is the number of encrypted, _pkb second Public key, y is the second part, r _b is the second random number, and [] _pkb is the second public key to encrypt the number in [].

S513. Decrypt the first encrypted data by using a preset first decryption algorithm and a set first private key to obtain first decrypted data; and use the first decryption algorithm and the first private key to decrypt the first encrypted data. The second encrypted data is decrypted to obtain the second decrypted data.

This step is expressed as a formula:

X '= PDO _SK ⁽¹⁾ (X), Y' = PDO _SK ⁽¹⁾ (Y)

Among them, X ′ is the first decrypted data, PDO is the first decrypted algorithm, _SK ⁽¹⁾ is the first private key, and Y ′ is the second decrypted data.

S514. Decrypt the first encrypted data and the first decrypted data by using a preset second decryption algorithm and a set second private key to obtain third decrypted data; by using the second decryption algorithm and the The second private key decrypts the second encrypted data and the second decrypted data to obtain fourth decrypted data.

This step is expressed as a formula:

X ”= PDT _SK ⁽²⁾ (X; X '), Y” = PDT _SK ⁽²⁾ (Y; Y')

Among them, X "is the third decrypted data, Y" is the fourth decrypted data, PDT is the second decryption algorithm, and _SK ⁽²⁾ is the second private key.

S515. Encrypt the difference between the first sum value and the second sum value by using a third public key to obtain an encrypted ciphertext of the data to be encrypted; the first sum value is the third decrypted data and the first Four sums of decrypted data, and the second sum is a sum of the first random number and the second random number.

This step is expressed as a formula:

S = X ”+ Y”, R = r _a + r _b

Then, [S] _pkc · ([R] _pkc ) ^N-1 = [SR] _pkc = [x + y] _pkc

Among them, S is the first sum value, R is the second sum value, _pkc is the third public key, and N is the size of the integer field.

The ordinary homomorphic addition encryption algorithm only supports the calculation on the ciphertext encrypted under the same key, and SAD in this algorithm, given the ciphertext encrypted by different keys, [x] pka, [x] pkb, and the introduction The random numbers r _a and r _b can also obtain the ciphertext corresponding to the plaintext addition.

In another embodiment, the encrypted data is homomorphically encrypted by using a multi-key privacy protection outsourcing computing algorithm to obtain encrypted ciphertext, including:

S51a. Split the data to be encrypted into a first part and a second part.

There are many ways to split the data to be encrypted into two parts. For example, the data to be encrypted is split into two parts in order from front to back. For example, each data in the data to be encrypted is classified according to attributes. There are two classes, each class is a part, and so on.

S51b: Encrypt the first part and the first random number respectively by using a set first public key, and multiply the two values obtained by encryption to obtain the first encrypted data; and separately set the second public key to each The second part and the second random number are encrypted, and the two encrypted values are multiplied to obtain the second encrypted data; the third random number and the second random number are summed by the first public key. Encrypt the difference of the first partial product to obtain third encrypted data; encrypt the difference between the fourth random number and the first random number and the second partial product by the second public key to obtain a fourth encryption data.

This step is expressed as a formula:

X = [x] _pka * [r _x ] _pka , Y = [y] _pkb * [r _y ] _pkb

S = [R _x ] _pka · ([x] _pka ) ^Nr _y = [R _x -r _y · x] _pka

T = [R _y ] _pkb · ([y] _pkb ) ^Nr _x = [R _y -r _x · y] _pkb

Among them, X is the first encrypted data, Y is the second encrypted data, S is the third encrypted data, T is the fourth encrypted data, _pka is the first public key, and [] _pka is the first public key pair []. Data is encrypted, x is the first part, r _x is the first random number, y is the second part, r _y is the second random number, [] _pkb is the data in [] encrypted by the second public key, _pkb is the second public key, R _x is the third random number, and R _y is the fourth random number.

S51c. Decrypt the first encrypted data by using a preset first decryption algorithm and a set first private key to obtain first decrypted data; and use the first decryption algorithm and the first private key to decrypt the first encrypted data. Decrypt the second encrypted data to obtain the second decrypted data; decrypt the third encrypted data by the first decryption algorithm and the first private key to obtain third decrypted data; and pass the first decryption algorithm Decrypt the fourth encrypted data with the first private key to obtain fourth decrypted data.

This step is expressed as a formula:

X ₁ = PDO _SK ⁽¹⁾ (X), Y ₁ = PDO _SK ⁽¹⁾ (Y) S ₁ = PDO _SK ⁽¹⁾ (S), T ₁ = PDO _SK ⁽¹⁾ (T)

Among them, PDO is the first decryption algorithm, _SK ⁽¹⁾ is the first private key, and X ₁ , Y ₁ , S ₁ , and T ₁ are the first decrypted data, the second decrypted data, the third decrypted data, and the fourth decrypted in this order. data.

S51d: Decrypt the first decrypted data and the first encrypted data by using a preset second decryption algorithm and a set second private key, and perform decryption by using the second decryption algorithm and the second private key. The second decrypted data and the first encrypted data are decrypted, and the two values obtained after decryption are multiplied to obtain a fifth decrypted data; the second decrypted algorithm and the second private key are used to pair the first Decrypt the three decrypted data and the third encrypted data to obtain a sixth decrypted data; and decrypt the fourth decrypted data and the fourth encrypted data by using the second decryption algorithm and the second private key, Get the seventh decrypted data.

This step is expressed as a formula:

h = PDT _SK ⁽²⁾ (X1; X) · PDT _SK ⁽²⁾ (Y1; X),

S2 = PDT _SK ⁽²⁾ (S1; S), T2 = PDT _SK ⁽²⁾ (T1; T).

Among them, h is the fifth decrypted data, PDT is the second decrypted algorithm, _SK ⁽²⁾ is the second private key, S2 is the sixth decrypted data, and T2 is the seventh decrypted data.

S51e. Encrypt the fifth decrypted data, the sixth decrypted data, and the seventh decrypted data by using a set third public key to obtain fifth encrypted data, sixth encrypted data, and seventh encrypted data; Encrypt the product of the first random number and the second random number with the third public key, and calculate the (N-1) -th power of the value obtained after encryption to obtain the eighth encrypted data; The third public key encrypts the third random number, and calculates the (N-1) th power of the value obtained after the encryption, to obtain ninth encrypted data; the fourth random number is obtained through the third public key. The number is encrypted, and the (N-1) -th power of the value obtained after the encryption is calculated to obtain the tenth encrypted data; N represents the size of the integer field.

This step is expressed as a formula:

H = [h] _pkc , S3 = [S2] _pkc , T3 = [T2] _pkc

S4 = ([r _x · r _y ] _pkc ) ^N-1 , S5 = ([Rx] _pkc ) ^N-1 , S6 = ([Ry] _pkc ) ^N-1 ,

Wherein, H, S3, T3, S4, S5, and S6 are the fifth decrypted data, the sixth decrypted data, the seventh decrypted data, the eighth encrypted data, the ninth encrypted data, and In the tenth encrypted data, pkc is a third public key, and N represents a size of an integer domain.

S51f: Multiply the fifth encrypted data, the sixth encrypted data, the seventh encrypted data, the eighth encrypted data, the ninth encrypted data, and the tenth encrypted data to obtain the The encrypted cipher text of the data to be encrypted.

This step is expressed as a formula:

H · T3 · S3 · S4 · S5 · S6 = [(h + (Rx-ry · x) + (Ry-rx · y) -rx · ry-Rx-Ry)] pkc = [x · y] _pkc

The multiplication homomorphism (SMD) given the ciphertexts [x] pka, [x] pkb, and random numbers rx, ry encrypted with different keys can also obtain the ciphertext corresponding to the plaintext multiplication.

After testing 1024bit (bit) integer, 80bit security level, 8-core 3.6GHZ (gigahertz) PC (personal computer), the time consumption of SAD is about 185ms, and the efficiency of SMD is 480ms, which greatly improves the area. Blockchain data calculation efficiency.

Therefore, the multi-key privacy protection outsourced computing algorithm can not only realize the encryption of the data to be encrypted, but also has higher computational efficiency than other homomorphic encryption algorithms. The data to be encrypted is data that needs to be protected, such as transaction data. Using multi-key privacy protection outsourcing computing algorithm to encrypt the encrypted data, the encrypted ciphertext can be obtained.

S52. Upload a request to calculate the encrypted ciphertext to a blockchain system, so that other blockchain nodes in the blockchain system calculate the encrypted ciphertext when receiving the request.

The request for calculating the encrypted cipher text may be specifically determined according to service requirements, such as calculating an average value or a variance of the encrypted cipher text. The first blockchain node can upload a request to calculate encrypted ciphertext through a smart contract or op_return. Smart contract is a computer protocol designed to spread, verify or execute contracts in an information-based manner. Smart contracts allow trusted transactions to be performed without a third party. These transactions are traceable and irreversible. OP_RETURN can realize the broadcasting and recording of data in the blockchain, omitting the calculation steps, thus achieving the purpose of saving time and computing power.

In one embodiment, the uploading a request for computing the encrypted ciphertext to a blockchain system includes:

S521. Upload the encrypted ciphertext to a distributed file system, and obtain a file hash value of the encrypted ciphertext.

Distributed file system (Distributed File System) refers to the physical storage resources managed by the file system are not necessarily directly connected to the local node, but connected to the node through a computer network. In order to be more suitable for blockchain application development, optionally, the distributed file system may be an IPFS file system (InterPlanetary File System). IPFS is a peer-to-peer distributed file system. It attempts to connect the same file system for all computing devices (IPFS miners).

The first blockchain node uploads the encrypted ciphertext to the distributed file system. The file hash value (file hash) can be calculated before uploading the encrypted ciphertext, or the hash value of the file can be returned when uploading IPFS.

S522. Store the correspondence between the file hash value and the encrypted cipher text in the distributed file system into a pre-created distributed hash table.

The first blockchain node creates a distributed hash-table (DHT, distributed hash table) in advance, and the DHT is accessed through the blockchain (Ethereum smart contract or Bitcoin op_return, etc.). DHT stores file hash indexes. Other blockchain nodes can obtain specific encrypted cipher text in the distributed file system through hash indexes.

S523. Upload a request to calculate the encrypted ciphertext to the blockchain system; the request includes a file hash value of the encrypted ciphertext.

In order to facilitate other blockchain nodes to find the encrypted ciphertext to be calculated, the request for calculating the encrypted ciphertext uploaded by the first blockchain node may include the file hash value of the encrypted ciphertext.

After the first blockchain node uploads a request to calculate the encrypted ciphertext to the blockchain, the second blockchain node can obtain the request from the blockchain, obtain the encrypted ciphertext according to the request, and obtain the The encrypted ciphertext is calculated.

Based on the same inventive concept, the present application also provides a blockchain data protection device 60, as shown in FIG. 6, including:

An encryption module 61, configured to perform homomorphic encryption on the encrypted data to obtain encrypted cipher text;

The request uploading module 62 is configured to upload a request for calculating the encrypted ciphertext to a blockchain system, so that other blockchain nodes in the blockchain system may receive the request for the encrypted ciphertext when receiving the request. Calculation.

In one embodiment, the encryption module 61 performs homomorphic encryption on the encrypted data by using a multi-key privacy protection outsourcing computing algorithm to obtain the encrypted ciphertext.

In one embodiment, the encryption module 61 obtains the encrypted ciphertext through the following operations:

Split the data to be encrypted into a first part and a second part;

Encrypt the sum of the first part and the first random number by the set first public key to obtain the first encrypted data; encrypt the sum of the second part and the second random number by the set second public key To obtain the second encrypted data;

Decrypt the first encrypted data by using a preset first decryption algorithm and a set first private key to obtain first decrypted data; and use the first decryption algorithm and the first private key to decrypt the second encrypted data Decrypt the encrypted data to obtain the second decrypted data;

Decrypting the first encrypted data and the first decrypted data by a preset second decryption algorithm and a set second private key to obtain third decrypted data; by the second decryption algorithm and the second The private key decrypts the second encrypted data and the second decrypted data to obtain fourth decrypted data;

The difference between the first sum value and the second sum value is encrypted by a third public key to obtain an encrypted ciphertext of the data to be encrypted; the first sum value is the third decrypted data and the fourth decryption The sum of data, the second sum value is the sum of the first random number and the second random number.

In another embodiment, the encryption module 61 obtains the encrypted ciphertext through the following operations:

Split the data to be encrypted into a first part and a second part;

The first part and the first random number are respectively encrypted by the set first public key, and the two encrypted values are multiplied to obtain the first encrypted data. The second public key is set to the first public key, respectively. The second part and the second random number are encrypted, and the two values obtained after encryption are multiplied to obtain a second encrypted data; the third random number is paired with the second random number and the first random number through the first public key. Encrypting a difference of a part of the product to obtain third encrypted data; encrypting a difference of the fourth random number with the first random number and the second part of the product by the second public key to obtain fourth encrypted data;

Decrypt the first encrypted data by using a preset first decryption algorithm and a set first private key to obtain first decrypted data; and use the first decryption algorithm and the first private key to decrypt the second encrypted data Decrypt the encrypted data to obtain the second decrypted data; decrypt the third encrypted data by the first decryption algorithm and the first private key to obtain third decrypted data; and use the first decryption algorithm and the Decrypting the fourth encrypted data by the first private key to obtain fourth decrypted data;

Decrypting the first decrypted data and the first encrypted data by a preset second decryption algorithm and a set second private key, and using the second decryption algorithm and the second private key to decrypt the first decrypted data and the first encrypted data Decrypt the second decrypted data and the first encrypted data, and multiply the two values obtained after decryption to obtain the fifth decrypted data; and decrypt the third by the second decryption algorithm and the second private key Decrypt the data and the third encrypted data to obtain a sixth decrypted data; decrypt the fourth decrypted data and the fourth encrypted data by the second decryption algorithm and the second private key to obtain a first Seven decrypted data;

Encrypt the fifth decrypted data, the sixth decrypted data, and the seventh decrypted data by using a set third public key to obtain the fifth encrypted data, the sixth encrypted data, and the seventh encrypted data; The third public key encrypts a product of the first random number and the second random number, and calculates the (N-1) -th power of the value obtained after encryption to obtain eighth encrypted data; through the first Three public keys encrypt the third random number, and calculate the (N-1) th power of the value obtained after encryption to obtain the ninth encrypted data; the fourth random number is performed by the third public key Encrypt and calculate the (N-1) power of the value obtained after encryption to obtain the tenth encrypted data; N represents the size of the integer field;

Multiplying the fifth encrypted data, the sixth encrypted data, the seventh encrypted data, the eighth encrypted data, the ninth encrypted data, and the tenth encrypted data to obtain the to-be-encrypted data The encrypted ciphertext of the data.

In one embodiment, the request uploading module 62 includes: an encrypted ciphertext uploading unit 621, configured to upload the encrypted ciphertext to a distributed file system, and obtain a file hash value of the encrypted ciphertext; The correspondence relationship storage unit 622 is configured to store a correspondence relationship between the file hash value and the encrypted cipher text in the distributed file system into a pre-created distributed hash table; and a request upload unit 623, configured to: Upload a request to the blockchain system to calculate the encrypted ciphertext; the request includes a file hash value of the encrypted ciphertext.

The other technical features of the above-mentioned blockchain data protection device described from the first blockchain node are the same as those of the above-mentioned blockchain data protection method described from the first blockchain node, and will not be repeated here.

In the following, from the perspective of the second blockchain node, the specific implementation methods of the blockchain data protection method and device of this application are described in detail.

As shown in FIG. 7, in one embodiment, a method for protecting blockchain data includes:

S71. Obtain a request for calculating an encrypted ciphertext uploaded by a first blockchain node from a blockchain system; the encrypted ciphertext is obtained by homomorphic encryption of data to be encrypted.

Blockchain is a new application model of computer technology such as distributed data storage, point-to-point transmission, consensus mechanism, and encryption algorithms. The so-called consensus mechanism is a mathematical algorithm for establishing trust and obtaining rights between different nodes in a blockchain system. Blockchain nodes refer to computers in the blockchain network, including mobile phones, miners, desktops, servers, etc. The person who operates a blockchain node can be an ordinary wallet user, a miner, and multiple people, etc. .

In order to improve the calculation efficiency, the encrypted ciphertext is obtained through a multi-key privacy protection outsourcing calculation algorithm for homomorphic encryption of encrypted data. The multi-key privacy protection outsourcing calculation algorithm supports addition (SAD), multiplication (SMD), etc. This kind of operation can not only realize the encryption of the data to be encrypted, but also has higher calculation efficiency than other homomorphic encryption algorithms. The data to be encrypted is data that needs to be protected, such as transaction data. Using multi-key privacy protection outsourcing computing algorithm to encrypt the encrypted data, the encrypted ciphertext can be obtained.

The first blockchain node uploads a request for computing the encrypted ciphertext to a blockchain system. The second blockchain node obtains the request from the blockchain system. If the request includes a file hash value of the encrypted ciphertext, the second blockchain node obtains the file hash value of the encrypted ciphertext.

S72. Acquire the encrypted ciphertext according to the request.

The second blockchain node needs to obtain the corresponding encrypted ciphertext according to the request for calculation. In one embodiment, the encrypted ciphertext is stored in a distributed file system; the request includes a file hash value of the encrypted ciphertext; and the obtaining the encrypted ciphertext according to the request includes:

S721. Access the distributed hash table created in advance by the first blockchain node through the blockchain system; the distributed hash table stores a file hash value of the encrypted ciphertext and the distribution Corresponding relationship of the encrypted cipher text in the file system.

The distributed hash table stores the correspondence between the file hash value and the encrypted cipher text in the distributed file system. The second blockchain node needs to access the distributed hash table through the blockchain system.

S722. According to the distributed hash table, look up the encrypted ciphertext corresponding to the file hash value in the request in the distributed file system.

The request contains a file hash value. According to the distributed hash table, the encrypted cipher text in the distributed file system corresponding to the file hash value can be determined, and then the encrypted cipher text is obtained from the distributed file system.

S73. Calculate the obtained encrypted ciphertext.

After the encrypted ciphertext is obtained, the second blockchain node can directly perform calculations on the encrypted ciphertext, such as averaging or variance. Since the multi-key privacy protection outsourcing calculation algorithm is adopted, not only the encryption of the blockchain data is realized, but also the efficiency of the calculation of the blockchain data is improved.

S74. Upload the calculation result to the blockchain system.

In order to improve the enthusiasm of the blockchain node, the second blockchain node calculates the encrypted ciphertext to obtain the calculation result, and uploads the calculation result to the blockchain system. The blockchain system verifies whether the calculation result uploaded by the second blockchain node is accurate. If it is accurate, it will issue token rewards to the second blockchain node that calculates accurately, such as a certain amount of bitcoin, etc. No token reward will be issued to the second blockchain node that uploads the calculation results.

Based on the same inventive concept, this application also provides a blockchain data protection device, as shown in FIG. 8, including:

A request obtaining module 81 is configured to obtain a request for calculating an encrypted ciphertext uploaded by a first blockchain node from a blockchain system; the encrypted ciphertext is obtained by homomorphic encryption of data to be encrypted;

An encrypted ciphertext obtaining module 82, configured to obtain the encrypted ciphertext according to the request;

A calculation module 83, configured to calculate the obtained encrypted cipher text;

The uploading module 84 is configured to upload the calculation result to the blockchain system.

In one embodiment, the encrypted ciphertext is stored in a distributed file system; the request includes a file hash value of the encrypted ciphertext; the encrypted ciphertext acquisition module 82 is configured to pass the blockchain The system accesses a distributed hash table created in advance by the first blockchain node; the distributed hash table stores a file hash value of the encrypted ciphertext and the encrypted password in the distributed file system Correspondence between texts; according to the distributed hash table, look up the encrypted ciphertext corresponding to the file hash value in the request in the distributed file system.

The other technical features of the above-mentioned blockchain data protection device described from the second blockchain node are the same as those of the above-mentioned blockchain data protection method described from the second blockchain node, and are not described herein.

An embodiment of the present application further provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the method for protecting a blockchain data according to any one of the foregoing is implemented. The storage medium includes, but is not limited to, any type of disk (including a floppy disk, a hard disk, an optical disk, a CD-ROM, and a magneto-optical disk), a ROM (Read-Only Memory, read-only memory), and a RAM (RandomAcceSS Memory, immediately (Memory), EPROM (EraSable Programmable Read-Only Memory, Erasable Programmable Read-Only Memory), EEPROM (Electrically EraSable Programmable Read-Only Memory, Electrically Erasable Programmable Read-Only Memory), flash memory, magnetic card or optical card. That is, the storage medium includes any medium that stores or transfers information in a readable form by a device (for example, a computer). It can be read-only memory, magnetic disk or optical disk, etc.

Each blockchain node (including the first blockchain node and the second blockchain node) in FIG. 1 is equivalent to a server. As shown in FIG. 9, it is a schematic structural diagram of a server according to an embodiment of the present application, including a processor 92 and a storage device 93. Those skilled in the art can understand that the structural device shown in FIG. 9 does not constitute a limitation on all servers, and may include more or fewer components than shown in the figure, or combine some components. The storage device 93 may be used to store an application program 91 and various functional modules. The processor 92 runs the application program 91 stored in the storage device 93 to execute various functional applications and data processing of the device. The storage device 93 may be an internal memory or an external memory, or include both an internal memory and an external memory. The internal memory may include a read-only memory, a programmable ROM (PROM), an electrically programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a flash memory, or a random access memory. External storage may include hard disks, floppy disks, ZIP disks, U disks, magnetic tapes, and so on. The storage devices disclosed in this application include, but are not limited to, these types of storage devices. The storage device 93 disclosed in the present application is only an example and not a limitation.

The processor 92 is a control center of the server, and uses various interfaces and lines to connect various parts of the entire computer. By running or executing software programs and / or modules stored in the storage device 93, and calling data stored in the storage device, Perform various functions and process data. If the server is the server of the first blockchain node, the processor 92 encrypts the encrypted data through a multi-key privacy protection outsourcing computing algorithm to obtain encrypted ciphertext, and uploads the encrypted ciphertext to the blockchain system to calculate the encrypted ciphertext. request. If the server is a server of a second blockchain node, the processor 92 obtains the request from the blockchain system, obtains the encrypted ciphertext according to the request, and calculates the obtained encrypted ciphertext.

It should be understood that although the steps in the flowchart of the drawings are sequentially displayed in accordance with the directions of the arrows, these steps are not necessarily performed in the order indicated by the arrows. Unless explicitly stated herein, the execution of these steps is not strictly limited, and they can be performed in other orders. Moreover, at least a part of the steps in the flowchart of the drawing may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily performed at the same time, but may be performed at different times. The execution order is also It is not necessarily performed sequentially, but may be performed in turn or alternately with other steps or at least a part of the sub-steps or stages of other steps.

It should be understood that the functional units in the embodiments of the present application may be integrated into one processing module, or each of the units may exist separately physically, or two or more units may be integrated into one module. The above integrated modules may be implemented in the form of hardware or software functional modules.

The above description is only part of the implementation of the present application. It should be noted that, for those of ordinary skill in the art, without departing from the principles of the present application, several improvements and retouches can be made. These improvements and retouches also It should be regarded as the protection scope of this application.

Claims (15)

1. A blockchain data protection method is characterized in that it includes:

   The first blockchain node performs homomorphic encryption on the encrypted data to obtain the encrypted ciphertext;

   Uploading, by the first blockchain node, a request for computing the encrypted ciphertext to a blockchain system;

   The second blockchain node obtains the request from the blockchain system;

   Obtaining, by the second blockchain node, the encrypted ciphertext according to the request;

   The second blockchain node calculates the obtained encrypted ciphertext, and uploads the calculation result to the blockchain system.
2. The method for protecting blockchain data according to claim 1, wherein the first blockchain node performs homomorphic encryption on the encrypted data to obtain encrypted ciphertext, comprising:

   The first blockchain node performs homomorphic encryption on encrypted data through a multi-key privacy protection outsourcing computing algorithm to obtain encrypted ciphertext.
3. The method for protecting blockchain data according to claim 2, wherein the first blockchain node performs homomorphic encryption on the encrypted data through a multi-key privacy protection outsourcing computing algorithm to obtain encrypted ciphertext, comprising:

   The first blockchain node splits the data to be encrypted into a first part and a second part;

   The first blockchain node encrypts the sum of the first part and the first random number by a set first public key to obtain the first encrypted data; and sets the second part and the second part by a set second public key. Encrypt the sum of the second random number to obtain second encrypted data;

   The first blockchain node decrypts the first encrypted data by using a preset first decryption algorithm and a set first private key to obtain first decrypted data; and using the first decryption algorithm and the first A private key decrypting the second encrypted data to obtain second decrypted data;

   The first blockchain node decrypts the first encrypted data and the first decrypted data by using a preset second decryption algorithm and a set second private key to obtain third decrypted data; through the first Two decryption algorithms and the second private key decrypt the second encrypted data and the second decrypted data to obtain fourth decrypted data;

   The first blockchain node encrypts the difference between the first sum value and the second sum value through a third public key to obtain an encrypted ciphertext of the data to be encrypted; the first sum value is the third The sum of the decrypted data and the fourth decrypted data, and the second sum is a sum of the first random number and the second random number.
4. The method for protecting blockchain data according to claim 2, wherein the first blockchain node performs homomorphic encryption on the encrypted data through a multi-key privacy protection outsourcing computing algorithm to obtain encrypted ciphertext, comprising:

   The first blockchain node splits the data to be encrypted into a first part and a second part;

   The first blockchain node encrypts the first part and the first random number respectively through a first public key that is set, and multiplies the two values obtained after encryption to obtain the first encrypted data. Two public keys respectively encrypt the second part and the second random number, and multiply the two values obtained after encryption to obtain the second encrypted data; the third random number and the third random number are obtained by the first public key Encrypt the difference between the second random number and the first partial product to obtain third encrypted data; perform the difference between the fourth random number and the first random number and the second partial product by using the second public key; Encrypt to obtain the fourth encrypted data;

   The first blockchain node decrypts the first encrypted data by using a preset first decryption algorithm and a set first private key to obtain first decrypted data; and using the first decryption algorithm and the first A private key decrypts the second encrypted data to obtain second decrypted data; decrypts the third encrypted data through the first decryption algorithm and the first private key to obtain third decrypted data; Decrypting the fourth encrypted data by the first decryption algorithm and the first private key to obtain fourth decrypted data;

   The first blockchain node decrypts the first decrypted data and the first encrypted data by using a preset second decryption algorithm and a set second private key, and by using the second decryption algorithm and the The second private key decrypts the second decrypted data and the first encrypted data, and multiplies the two values obtained after decryption to obtain a fifth decrypted data; the second decryption algorithm and the second decrypted data are obtained. A private key decrypts the third decrypted data and the third encrypted data to obtain a sixth decrypted data; the fourth decrypted data and the first decrypted data are obtained through the second decryption algorithm and the second private key. Four encrypted data are decrypted to obtain seventh decrypted data;

   The first blockchain node encrypts the fifth decrypted data, the sixth decrypted data, and the seventh decrypted data by using a set third public key to obtain the fifth encrypted data and the sixth encrypted data. And the seventh encrypted data; encrypt the product of the first random number and the second random number with the third public key, and calculate the (N-1) -th power of the value obtained after encryption to obtain the first Eight encrypted data; the third random number is encrypted by the third public key, and the (N-1) -th power of the value obtained after the encryption is calculated, to obtain the ninth encrypted data; by the third public key Encrypt the fourth random number, and calculate the (N-1) th power of the value obtained after encryption to obtain tenth encrypted data; N represents the size of the integer field;

   The first blockchain node sends the fifth encrypted data, the sixth encrypted data, the seventh encrypted data, the eighth encrypted data, the ninth encrypted data, and the tenth encrypted data. Multiply to obtain the encrypted ciphertext of the data to be encrypted.
5. The method for protecting blockchain data according to claim 1, wherein the uploading a request for computing the encrypted ciphertext to the blockchain system by the first blockchain node comprises:

   Uploading the encrypted ciphertext to a distributed file system by the first blockchain node, and obtaining a file hash value of the encrypted ciphertext;

   Storing, by the first blockchain node, a correspondence between the file hash value and the encrypted ciphertext in the distributed file system into a pre-created distributed hash table;

   The first blockchain node uploads a request for computing the encrypted ciphertext to a blockchain system; the request includes a file hash value of the encrypted ciphertext.
6. The method for protecting blockchain data according to claim 5, wherein the obtaining, by the second blockchain node according to the request, the encrypted ciphertext comprises:

   The second blockchain node accesses the distributed hash table through the blockchain system;

   The second blockchain node searches the distributed file system for the encrypted ciphertext corresponding to the file hash value in the request according to the distributed hash table.
7. The method for protecting blockchain data according to any one of claims 1 to 6, wherein the second blockchain node calculates the obtained encrypted ciphertext, and uploads the calculation result to the blockchain The system, after that, also includes:

   When the blockchain system verifies that the calculation result is valid, a token reward is issued to the second blockchain node.
8. A blockchain data protection method is characterized in that it includes:

   Homomorphically encrypt encrypted data to obtain encrypted ciphertext;

   Upload a request to calculate the encrypted ciphertext to a blockchain system, so that other blockchain nodes in the blockchain system calculate the encrypted ciphertext when receiving the request.
9. The method for protecting blockchain data according to claim 8, characterized in that the homomorphic encryption of the data to be encrypted to obtain encrypted ciphertext comprises:

   The encrypted data is homomorphically encrypted by the multi-key privacy protection outsourcing computing algorithm to obtain the encrypted ciphertext.
10. A blockchain data protection method is characterized in that it includes:

    Obtaining a request for calculating an encrypted ciphertext uploaded by a first blockchain node from a blockchain system; the encrypted ciphertext is obtained by homomorphic encryption of data to be encrypted;

    Obtaining the encrypted ciphertext according to the request;

    Calculate the obtained encrypted ciphertext;

    The calculation results are uploaded to the blockchain system.
11. The method for protecting blockchain data according to claim 10, wherein the encrypted ciphertext is stored in a distributed file system; and the request includes a file hash value of the encrypted ciphertext;

    The obtaining the encrypted ciphertext according to the request includes:

    Accessing a distributed hash table created in advance by the first blockchain node through the blockchain system; the distributed hash table stores a file hash value of the encrypted ciphertext and the distributed file The corresponding relationship of the encrypted cipher text in the system;

    According to the distributed hash table, look up the encrypted ciphertext corresponding to the file hash value in the request in the distributed file system.
12. A blockchain data protection system, comprising a first blockchain node and a second blockchain node;

    The first blockchain node is configured to perform homomorphic encryption on the encrypted data to obtain an encrypted ciphertext; upload a request for calculating the encrypted ciphertext to a blockchain system;

    The second blockchain node is configured to obtain the request from the blockchain system; obtain the encrypted ciphertext according to the request; calculate the obtained encrypted ciphertext, and upload the calculation result to the area Blockchain system.
13. A blockchain data protection device is characterized in that it includes:

    An encryption module for homomorphically encrypting the encrypted data to obtain encrypted cipher text;

    A request uploading module is configured to upload a request for calculating the encrypted ciphertext to a blockchain system, so that other blockchain nodes in the blockchain system perform the encryption ciphertext upon receiving the request. Calculation.
14. A blockchain data protection device is characterized in that it includes:

    A request obtaining module, configured to obtain a request for calculating an encrypted ciphertext uploaded by a first blockchain node from a blockchain system; the encrypted ciphertext is obtained by homomorphic encryption of data to be encrypted;

    An encrypted ciphertext obtaining module, configured to obtain the encrypted ciphertext according to the request;

    A calculation module for calculating the obtained encrypted ciphertext;

    An uploading module is configured to upload the calculation result to the blockchain system.
15. A computer-readable storage medium having stored thereon a computer program, characterized in that when the program is executed by a processor, the method for protecting a blockchain data according to any one of claims 1 to 11 is implemented.

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