A non-interactive and verifiable privacy-preserving blockchain sequential query method

Abstract

A non-interactive and verifiable privacy-preserving blockchain sequential query method is proposed. This method converts the current floating-point form into two parts using scientific notation and enriches the sequential revelation encryption to protect distance information. Then, combining scientific notation and the inherent Merkle tree structure, a certified hybrid search tree (AHSTree) index structure is constructed, supporting authenticated sequential operations on bit-to-ciphertext. This structure is implemented using Setup, Encrypt, Compare, and Decrypt algorithms. The benefits are: it addresses the limitations of existing solutions for encrypted blockchain databases due to multi-round communication and high encryption costs. Utilizing techniques such as sequential explicit encryption, Merkle tree structure, and scientific notation, it proposes the first encrypted blockchain database with operational authentication and non-interactive capabilities, meeting practical throughput requirements, and introducing an authenticated hybrid search tree to ensure no omissions or tampering.

Description

Technical Field

[0001] This invention relates to the field of blockchain data privacy protection technology, specifically to a non-interactive and verifiable privacy-preserving sequential query method for blockchain. Background Technology

[0002] In recent years, the rapid development of blockchain technology has attracted widespread attention and discussion globally. The successful application of these projects has driven the continuous evolution and improvement of blockchain database technology, providing a new paradigm for data storage and management. Blockchain databases store a wide variety of data, including cryptocurrency transaction records and personal data, giving them broad application prospects.

[0003] One of the core characteristics of blockchain databases is transparency, which allows users to perform various basic, sequential data processing operations on the stored data. For example, users can easily query transactions whose output balances fall within a specific range. Similar to traditional centralized databases, blockchain databases ensure the traceability of operations, guaranteeing the security and integrity of data processing. Furthermore, blockchain databases possess distributed characteristics, decentralized consensus mechanisms, and tamper-proof data protection, giving blockchain technology unique advantages in multiple fields.

[0004] Users' strong interest in blockchain databases stems not only from their transparency and traceability but also from a range of compelling attributes. First, the decentralized nature of blockchain databases means they do not rely on a single central authority, thus improving system robustness and availability. Second, due to the data consensus mechanism ensuring tamper-proof integrity, blockchain databases possess a high degree of data trustworthiness and can be used in critical areas such as financial transactions and contract enforcement. However, precisely because of these advantages, blockchain database applications face a series of challenges in scenarios involving private data.

[0005] While blockchain databases have achieved significant results in ensuring transparency and data integrity, this transparency itself has become a threat to data privacy. In transparent blockchain databases, each participant, including service nodes, can access and use the plaintext data of other participants without explicit authorization. This characteristic has led to data breaches and misuse in practical applications. A typical example is the non-fungible token (NFT) data breach, where transparency allowed users to access token data and subsequently create new tokens through unauthorized copying, resulting in economic losses.

[0006] These issues severely hinder the implementation and development of blockchain databases in several key areas. Particularly in scenarios involving private data, even with a transparent blockchain database, each participant could potentially access and use other participants' plaintext data without permission, posing a threat. In such cases, data privacy and security are questioned. Therefore, to more widely apply blockchain databases to private data management services, it is urgent to address the problems of data leakage and misuse.

[0007] In distrustful blockchain environments, service nodes may return erroneous or tampered data processing results for profit, making data security and integrity paramount. To address this, it is necessary to build cryptographic blockchain databases that support authenticated, sequence-oriented data processing operations. Such databases must not only meet data sorting requirements but also ensure that authenticated users receive legitimate and authorized results during data processing. However, current research primarily focuses on provably secure order-preserving cryptographic techniques, which still face challenges in terms of communication overhead and throughput.

[0008] Current research primarily focuses on provably secure order-preserving cryptography to achieve secure, sequence-oriented data processing. For example, Chen et al. proposed a provably secure cryptographic blockchain database at ICDE 2022, combining order-preserving cryptography with techniques that store stateful and ordered ciphertext. However, this scheme suffers from high communication overhead and low throughput. Users need to perform multiple rounds of communication to encrypt or query data, which is clearly impractical in real-world applications. Furthermore, considering provable security, there are difficulties in implementing an order-preserving cryptographic-based blockchain database while maintaining non-interactivity.

[0009] Another promising technique is order-revealing encryption, which replaces the tree structure of order-preserving encryption with a publicly computable function, allowing the underlying order of the encrypted data to be revealed with just one round of communication. However, current order-revealing encryption schemes have security limitations, especially when dealing with exponentially large fields. Specifically, current schemes may leak the index of the first different bit between two pieces of data, allowing an adversary to infer the approximate distance between the two pieces of data and, consequently, the user's private information. In such cases, attackers could profit through methods such as ad recommendations or even launch more direct attacks against users.

[0010] Therefore, the current challenge lies in designing a cryptographic blockchain database that enables non-interactive, authenticated, sequence-oriented data processing operations. This requires overcoming limitations in communication overhead and throughput, as well as addressing security issues present in current solutions. Effectively resolving these challenges will provide a more solid technical foundation for the wider application of blockchain databases. Summary of the Invention

[0011] The purpose of this invention is to address the shortcomings of existing technologies by proposing a non-interactive and verifiable privacy-preserving sequential query method for blockchains. This method aims to solve the problems that existing solutions for encrypted blockchain databases suffer from lower throughput than required due to the impact of multiple rounds of communication and high encryption costs.

[0012] A non-interactive and verifiable privacy-preserving blockchain sequential query method utilizes scientific notation to convert the current floating-point form into two parts and enriches the sequential revelation encryption to protect distance information. Then, combining scientific notation and the inherent Merkle tree structure, an authenticated hybrid search tree (AHSTree) index structure is constructed, supporting authenticated sequential operations on bit-to-ciphertext. This structure is implemented using Setup, Encrypt, Compare, and Decrypt algorithms, as detailed below: The Setup algorithm is run by the data owner to generate system parameters; given a security parameter λ, the data owner keeps the secret key sk confidential and publishes PP as a public parameter; The Encrypt algorithm is run by the data owner to encrypt his / her data; to run the algorithm, the data owner first specifies the data size t, the size of the exponent field N, and the number of bits n in the value; for each data... The data owner converted it to scientific notation and extracted the value. Sum of Indices To ensure compatibility with varying data precision requirements across different data engines, data owners use a scaling factor L, i.e. Further conversion Data owners use encrypted indices generate By introducing a one-time random value r, a pseudo-random function F, a hash function H, and a random permutation π, the ciphertext of the exponent is semantically secure; the data owner then uses the encrypted value... generate In the Encrypt algorithm, to ensure data security, the data owner chooses the symmetric encryption scheme SE and authenticates the data before uploading it. right Encryption is performed; the data owner generates the original data. ciphertext The data owner will trade Upload to the service node to enjoy the services of the blockchain database; The Compare algorithm, run by authorized users and service nodes, is used to compare the order of two pieces of data in ciphertext. The authorized user first requests the secret key sk from the data owner via a secure communication channel, and then... Calculate comparison labels Using comparison labels Service node computes ciphertext and Comparison results where b = 0 indicates b = 1 means b = 2 means ; The Decrypt algorithm authorizes users to first verify the operation results, including ensuring there are no omissions or tampering; the authorized user then executes the corresponding decryption function using the symmetric encryption key sek and the random value r of message m. , returns the original raw data m.

[0013] Preferably, the specific algorithm process of the Setup algorithm is as follows: Input: Security parameter λ; Output: Secret key sk, common parameters PP; choose ; generate ; choose ; generate ; choose ; choose ; choose ; choose ; Generate secret key ; Generate common parameters .

[0014] The beneficial effects are as follows: existing solutions for encrypted blockchain databases are affected by multi-round communication and high encryption costs. By utilizing techniques such as sequential explicit encryption, Merkle tree structure and scientific notation, the first encrypted blockchain database with operational authentication and non-interactivity is proposed, which meets the actual throughput requirements and introduces an authenticated hybrid search tree to ensure no omissions and tampering. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall framework of the non-interactive and verifiable privacy-preserving blockchain sequential query method described in this invention. Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] To achieve the objectives described in this invention, the following definitions are required: Definition 1: Data Owner Data owners are typically honest, cooperative individuals or organizations that possess the original data. They upload encrypted data to service nodes to enjoy blockchain database services.

[0018] Definition 2: Service Node Service nodes are large service providers (such as iCloud and Microsoft Azure) that store fully replicated blockchain databases and stay online to provide computing and storage services to other entities.

[0019] Definition 3: Authorized User Authorized users, with the permission of the data owner, can access the blockchain database, perform sequential data processing operations through service nodes, and authenticate the operation results obtained from the service nodes.

[0020] In this invention, the data owner is trusted. He / she treats the blockchain database as a data management platform and uploads encrypted data to the service node. Based on necessary credentials, such as social prestige, professional information, and social relationships, the data owner grants authorized users access to the original data. Therefore, the data owner and authorized users trust each other, but neither trusts the service node. The service node is seen as a potential adversary that might return incorrect or tampered operational results for profit.

[0021] A non-interactive and verifiable privacy-preserving blockchain sequential query method utilizes scientific notation to convert the current floating-point form into two parts and enriches the sequential revelation encryption to protect distance information. Then, combining scientific notation and the inherent Merkle tree structure, an authenticated hybrid search tree (AHSTree) index structure is constructed, supporting authenticated sequential operations on bit-to-ciphertext. This structure is implemented using Setup, Encrypt, Compare, and Decrypt algorithms, as detailed below: The Setup algorithm is run by the data owner to generate system parameters; given a security parameter λ, the data owner keeps the secret key sk confidential and publishes PP as a public parameter; The Encrypt algorithm is run by the data owner to encrypt his / her data; to run the algorithm, the data owner first specifies the data size t, the size of the exponent field N, and the number of bits n in the value; for each data... The data owner converted it to scientific notation and extracted the value. Sum of Indices To ensure compatibility with varying data precision requirements across different data engines, data owners use a scaling factor L, i.e. Further conversion Data owners use encrypted indices generate By introducing a one-time random value r, a pseudo-random function F, a hash function H, and a random permutation π, the ciphertext of the exponent is semantically secure; the data owner then uses the encrypted value... generate In the Encrypt algorithm, to ensure data security, the data owner chooses the symmetric encryption scheme SE and authenticates the data before uploading it. right Encryption is performed; the data owner generates the original data. ciphertext The data owner will trade Upload to the service node to enjoy the services of the blockchain database; The Compare algorithm, run by authorized users and service nodes, is used to compare the order of two pieces of data in ciphertext. The authorized user first requests the secret key sk from the data owner via a secure communication channel, and then... Calculate comparison labels Using comparison labels Service node computes ciphertext and Comparison results where b = 0 indicates b = 1 means b = 2 means ; The Decrypt algorithm authorizes users to first verify the operation results, including ensuring there are no omissions or tampering; the authorized user then executes the corresponding decryption function using the symmetric encryption key sek and the random value r of message m. , returns the original raw data m.

[0022] The specific algorithm process of the Setup algorithm is as follows: Input: Security parameter λ; Output: Secret key sk, public parameter PP; Selection ;generate ;choose ;generate ;choose ;choose ;choose ;choose Generate secret key Generate common parameters .

[0023] The specific algorithm process of the Encrypt algorithm is as follows: Input: Secret key sk and raw data Output: Ciphertext C, data size t, exponent field size N, number of bits in the value n; Generate decryption key , for do, ; for do, , binary representation , for do, , SE is a symmetric encryption scheme; data encryption is... , The transaction package is .

[0024] The specific algorithm process of the Compare algorithm is as follows: enter: ciphertext , ciphertext , Comparison markers The authorized user section is as follows: Output the comparison results. Analysis ,calculate ,calculate ,generate Comparison markers The service node section is as follows: (Analysis) Analysis ( Analysis Analysis Set initial comparison results , let if then b=0 means else if then b=0, else if Then b=2 means if b=1 then for do if then continue, else if then b=2 means break, else if then b=0 means break, output .

[0025] To facilitate understanding, the following example illustrates the points in detail: Step 1: System Initialization; The Init phase is executed between the data owner and the service node to generate system parameters, upload data to the blockchain database, and initialize AHSTree.

[0026] Data owner: Given a security parameter λ, the data owner runs the OrderEBD.Setup() algorithm to generate a secret key. and common parameter PP. Assume the original dataset of the data owner is... The data owner runs the OrderEBD.Encrypt() algorithm to obtain the ciphertext. Then Packaged into a transaction set In the middle. Then, the data owner will Upload to the service node to enjoy the blockchain database service. For simplicity, let's assume that... In this context, the ciphertext is ordered.

[0027] Service Node: Based on blockchain consensus (such as PBFT), service nodes collaborate to set up transaction sets. Packaged onto the blockchain. When these transactions are successfully stored on the blockchain, each service node downloads the transaction data and initializes its local AHSTree state. Through consensus, each service node maintains a completely duplicated blockchain database and AHSTree. Specifically, the service node will set transaction sets... Ciphertext in It is divided into two parts: the index part Sum of values Based on OrderEBD.Compare(), the service node can divide the index portion. Arranged into a binary search tree, where each vertex contains the ciphertext of the exponent and a value pointer. Furthermore, in a binary search tree, the right exponent is greater than the parent vertex, and the left exponent is less than the parent vertex. Subsequently, for ciphertexts with the same exponent portion, since... Once established, service nodes can This will be arranged into a prefix tree. In the prefix tree, the value of each vertex is taken from {0, 1, 2}, and the leaf vertices also contain the addresses of the data on the blockchain database. Meanwhile, the value pointer points to the root of the prefix tree, where each value in the current prefix tree has the same exponent. When multiple transactions have the same value, the service node merges them into a single vertex. Afterward, the service node proceeds from bottom to top by executing... Merkle trees are combined to compute hash values, thus generating an AHSTree. Finally, the service node initializes the AHSTree state. .

[0028] Step 2: Data Insertion. The Insert phase is performed between the data owner and the service node to insert new data into the blockchain database and update the AHSTree.

[0029] Data owner Using new data The data owner generates a comparison tag CL and runs the BlockO-RE.Encrypt() algorithm to generate a new transaction. CL is packaged into Subsequently, the data owner will Upload to the service node.

[0030] service node When a transaction is received from the data owner At this point, the service node packages the transaction along with the current operation log onto the blockchain through blockchain consensus. Then, the service node inserts the transaction into the AHSTree following the example above. Specifically, the service node compares the exponent and value portions with existing vertices in the AHSTree by running the OrderEBD.Compare() algorithm. Next, the service node updates the AHSTree state to... .

[0031] Step 3: Data Query. The Query phase is executed between authorized users and service nodes and is used for encrypted range queries.

[0032] Authorized users Authorized users first obtain the secret key sk from the data owner through a secure communication channel. Based on sk, authorized users then define their query scope. Convert to ciphertext and Subsequently, authorized users generate comparison tags. And Packaged into query transaction In the middle, then Send to the service node.

[0033] service node The service node first starts by querying transactions. Parsing Then, based on the current AHSTree states s, the service nodes combine the OrderEBD.Compare() algorithm to obtain the query results. Finally, the service node packages this operation record into the blockchain for traceability and uses the operation result as... VO is returned, where VO represents the authentication information generated by AHSTree.

[0034] Step 4: Data Decryption. The decryption phase is performed by the authorized user to verify the operation result and restore the original data. Specifically, when the query result R is received from the service node, the authorized user uses the authentication information VO to verify the operation result to ensure that there are no omissions or tampering. If the authentication process returns true, the authorized user uses the symmetric encryption key sek and a random value... Running a symmetric decryption scheme To recover the original data .

[0035] The technical solution described in this invention addresses the limitations of existing encrypted blockchain database solutions due to multi-round communication and high encryption costs. By utilizing techniques such as sequential explicit encryption, Merkle tree structure, and scientific notation, the first encrypted blockchain database with operational authentication and non-interactivity is proposed, meeting practical throughput requirements. Furthermore, an authenticated hybrid search tree is introduced to ensure no omissions or tampering.

[0036] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A non-interactive and verifiable privacy-preserving blockchain sequential query method, characterized in that: The privacy-preserving blockchain sequential query method utilizes scientific notation to convert the current floating-point form into two parts and enriches the sequential revelation encryption to protect distance information. Then, combining scientific notation and the inherent Merkle tree structure, an authenticated hybrid search tree (AHSTree) index structure is constructed, supporting authenticated sequential operations on bit-level ciphertext. This structure is implemented using Setup, Encrypt, Compare, and Decrypt algorithms, as detailed below: The Setup algorithm is run by the data owner to generate system parameters; given a security parameter λ, the data owner keeps the secret key sk confidential and publishes PP as a public parameter; The Encrypt algorithm is run by the data owner to encrypt his / her data; to run the algorithm, the data owner first specifies the data size t, the size of the exponent field N, and the number of bits n in the value; for plaintext data m i The data owner converted it to scientific notation and extracted the value x. i And the exponent y i To ensure compatibility with varying data precision requirements across different data engines, data owners use a scaling factor L to calculate... , z i Further assign to x i Data owners use encrypted index y i generate ; By introducing a one-time random value r, a pseudo-random function F, a hash function H, and a random permutation π, the ciphertext of the exponent is semantically secure; the data owner then uses the encrypted value x... i generate In the Encrypt algorithm, to ensure data security, the data owner chooses the symmetric encryption scheme SE and authenticates the data before uploading it. For plaintext data m i Encryption is performed; the data owner generates plaintext data m. i ciphertext c i The data owner will trade tx i Upload to the service node to enjoy the services of the blockchain database; The Compare algorithm, run by an authorized user and a service node, is used to compare the order of two pieces of data in ciphertext. The authorized user first requests the secret key sk from the data owner via a secure communication channel, and then assigns the ciphertext c to the specified data. i Calculate comparison label c L Using comparison label c L The service node calculates the comparison result of ciphertexts c1 and c2. Where b = 0 represents m1 <m2 ，b="1表示m1=m2，b" = 2表示m1> m2；< / m2> The Decrypt algorithm authorizes users to first verify the operation results, including ensuring there are no omissions and no tampering; authorized users use the symmetric encryption key sek and the ciphertext C. i The random value r executes the corresponding decryption function. Returns the original plaintext data m i .

2. The non-interactive and verifiable privacy-preserving blockchain sequential query method of claim 1, wherein: The specific algorithm process of the Setup algorithm is as follows: Input: a security parameter λ; output: a secret key sk, public parameters PP; select ; generate ; select ; generate ;choose ;choose ;choose ;choose Generate secret key Generate common parameters .

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