Block chain-based double-stream video conference privacy tracing method

Abstract

The invention provides a double-stream video conference privacy tracing method based on a block chain, and the method comprises the steps: building a tracing evidence obtaining model which comprises information uplink and tracing evidence obtaining; the information uploading comprises the following steps: in a video conference process, audio and video data and related conference information are uploaded to an interstellar file system for storage and verification after being subjected to encryption and signature processing through a threshold ring signature mechanism, and key evidence is uploaded to a block chain; the intelligent contract is used for automatically managing data storage; the traceability evidence obtaining comprises the following steps: after leaked picture information is obtained, detecting a traceability identifier in a video or a picture, and comparing the traceability identifier with information stored on a chain; a secret divulging block point is automatically tracked and positioned through an intelligent contract, and the real identity of a secret divulging party is decrypted. According to the method, tampering resistance, transparency, decentration and anonymity of chain information in the traceability evidence obtaining process are achieved, and automatic evidence obtaining and traceability operation is supported.

Description

Technical Field

[0001] The present invention belongs to the field of information security, and particularly relates to a privacy traceability method for dual-stream video conferencing based on blockchain. Background Art

[0002] As an important means of information exchange, video conferencing has become an indispensable part of people's daily work and life. The rise of blockchain technology provides a new solution to the problems of privacy protection and evidence collection and traceability in video conferencing. Based on the characteristics of blockchain such as transparency, immutability, and decentralization, a secure and trustworthy privacy traceability mechanism for dual-stream video conferencing can be constructed. By real-time uploading and storing audio and video data during the video conferencing process, the verifiability of data sources and the fairness of responsibility traceability can be effectively achieved, providing strong support for the security and privacy protection of video conferencing.

[0003] Traditional video conferencing traceability and evidence collection systems usually adopt a centralized architecture, and manage and verify user identities and conference data through a centralized server. However, this architecture has the following problems: Single point of failure problem: The failure or attack of the centralized server will lead to the paralysis of the entire system, seriously affecting the effectiveness and reliability of evidence collection. Information tampering and forgery: The centralized storage method is easily tampered with or forged maliciously, making it difficult to ensure the integrity and credibility of data. Privacy leakage and permission management problems: In the traditional architecture, the identity information and data of users are all managed by the centralized server, there is a risk of leakage, and the access control mechanism is relatively weak. Blockchain can effectively solve the single point of failure and information tampering problems in traditional systems through its decentralized, immutable, and transparent characteristics. At the same time, the smart contract technology based on blockchain can realize automated data verification and permission management, thereby enhancing the security and credibility of the system.

[0004] In addition, Liu et al. (Reference: Liu Z, Yu X, Liu N, et al. Integrating AI with detection methods, IoT, and blockchain to achieve food authenticity and traceability from farm-to-table[J]. Trends in Food Science & Technology, 2025: 104925.) proposed an innovative method of integrating artificial intelligence (AI), the Internet of Things (IoT), and blockchain technology to optimize the entire process of data collection and management. In this solution, AI technology is used for intelligent analysis and decision support, IoT technology enables extensive physical device connection and data collection, while blockchain provides an immutable and traceable guarantee for data storage and transmission. Through this integrated architecture, not only the efficiency and accuracy of data collection are improved, but also the security and credibility of traceable information are significantly enhanced.

[0005] Brandín et al. (Reference: Brandín R, Abrishami S. IoT-BIM and blockchain integration for enhanced data traceability in offsite manufacturing[J]. Automation in Construction, 2024, 159: 105266.) proposed a traceability management model based on information modeling (Supply Chain Management Model - Product Data Object, SCMM-PDO) and constructed a traceability management framework with high security and transparency. This model standardizes and uniformly manages the data of different supply chain nodes through information modeling technology, and realizes the trustworthy sharing and traceability of data under the participation of multiple parties by virtue of the immutability and transparency of blockchain. At the same time, SCMM-PDO designs a perfect data access and authorization mechanism to ensure the protection of the privacy and business secrets of all parties on the premise of data openness and transparency.

[0006] Although the above research has made remarkable progress in improving data transparency and traceability, most solutions mainly focus on the authenticity and integrity of on-chain data, and pay insufficient attention to the protection of data privacy. Due to the public nature of blockchain, the public storage and transmission of sensitive data on the chain may lead to the risk of privacy leakage. Therefore, how to protect user privacy while ensuring traceability has become an urgent problem in the current blockchain traceability and evidence collection technology. Summary of the Invention

[0007] Object of the Invention: The technical problem to be solved by the present invention is to provide a privacy traceability method for two-stream video conferencing based on blockchain. Through a decentralized architecture and an automated execution mechanism of smart contracts, an efficient, secure, and tamper-proof traceability and evidence collection function is achieved. In addition, in order to protect the privacy and authorized access control of information on the chain while ensuring traceability and accountability, the present invention designs a threshold traceable ring signature method to achieve an effective balance between privacy protection and liability tracing.

[0008] The method of the present invention includes: establishing a traceability and evidence collection model, which includes information uploading to the chain and traceability and evidence collection; The information uploading to the chain includes: during the video conferencing process, audio and video data and related conference information are encrypted and signed through a threshold ring signature mechanism, and then uploaded to the InterPlanetary File System (IPFS) for storage and verification. Key evidence (such as watermark information, conference information, personnel information, etc.) will be uploaded to the blockchain; and a smart contract (an automated protocol based on blockchain that does not rely on a third-party intermediary) is used for automated management of data storage; The traceability and evidence collection includes: after obtaining the leaked picture information, by detecting the traceability identifier W in the video or picture, and comparing it with the information stored on the chain for comparison, is a hash function, , where represents an arbitrary string length, G represents an elliptic curve group, means mapping any binary input to an element in G; the smart contract automatically traces and locates the leaked block point, and decrypts the true identity of the leaking party through multi-party cooperation.

[0009] The information uploading to the chain specifically includes the following steps: Step a1, data collection and preprocessing; Step a2, information authentication; Step a3, uploading the evidence chain.

[0010] Step a1 includes: the video conferencing terminal automatically collects the original information including the conference video and documents, and embeds the traceability identifier W in the video frame: (1), where, represents the public identity identifier of user o, represents the unique conference identifier, Indicates the timestamp of watermark generation; the traceability identifier W is an anti-screen capture digital watermark, and the traceability identifier W will be bound to the identity of the participant for subsequent leak tracing.

[0011] Step a2 includes: saving the information collected by the current user (conference video information, watermark information, personnel identity information), encrypting it, and uploading it to the InterPlanetary File System IPFS, and returning an address information , and performing hash encryption on the address information obtained from the InterPlanetary File System IPFS; where Indicates the storage address in the InterPlanetary File System IPFS where the x-th information collected by the current user is stored; For the current user, use the threshold traceable ring signature algorithm based on zero-knowledge proof to perform signature to obtain , is the encrypted value of the user's public identity, is the non-interactive zero-knowledge proof (Non-Interactive Zero-Knowledge Proof, NIZK) generated using Schnorr signature and Okamoto protocol; The threshold traceable ring signature algorithm specifically includes: Input security parameter , is the security strength, and through , generate the public parameters of the system, where is the pairing group, is the system generator, represents the bilinear mapping, is the finite field; represents initializing the public parameters pp of the system by the security parameter ; Save the video conference information of the current user, encrypt it, and upload it to the InterPlanetary File System IPFS, and return , and the current user needs to use the signature algorithm to perform signature on , where represents to the power, is a random number; represents the public key of the tracer, PID represents the user's public identity; use Schnorr and Okamoto to generate a non-interactive zero-knowledge proof , to ensure the validity of the signature and the security of the private key, where the formula for generating the challenge value is: (2), where represents the challenge value of the members within the \(i\)-th ring, represents the message to be signed, and respectively represent the Schnorr commitment generated by the members within the \((i - 1)\)-th ring and the Okamoto commitment generated by the members within the \((i - 1)\)-th ring; represents the exclusive OR operation; Generate the non - interactive zero - knowledge proofs of the members within the ring in sequence: (3), where represents the Schnorr commitment of the \(i\)-th ring member, and \(z\) is a random number; represents the Schnorr response value of the \(i\)-th ring member, \(sk\) is the private key of the signer, is a random value; (4), where is the Okamoto commitment of the \(i\)-th ring member, represents the public identity of the \(i\)-th ring member, is the Okamoto response value of the \(i\)-th ring member.

[0012] Next, generate the verification information of the signer: Calculate the challenge value: (5), where represents the challenge value of the signer, \(R\) represents the number of members within the ring, represents the modulo operation, is a prime number; Schnorr: (6), Okamoto: (7), where , , , respectively represent the commitment value of the Schnorr signature generated by the signer, the response value of the Schnorr signature, the commitment value of the Okamoto signature, and the response value of the Okamoto signature; Finally, generate the traceable ring signature : (8), where, respectively represent the commitment value, response value, and challenge value of the members within the m-th ring, where m ranges from 1 to R; Final combined member signature information ( ).

[0013] Step a3 includes: encrypting the user's signature, the collected traceability identifier W, the collected conference video and documents, and uploading them to the InterPlanetary File System IPFS, calculating the hash values of the signature and the traceability identifier, and finally uploading the information to the blockchain to form an evidence chain M: (9), where respectively represent the information stored by a user in the InterPlanetary File System IPFS, the hash value of the signature, and the hash value of the watermark information. k ranges from 1 to H1, and H1 represents the number of people participating in the meeting.

[0014] The specific traceability evidence collection includes the following steps: Step b1, anomaly detection and triggering traceability; Step b2, multi-party collaborative information traceability.

[0015] Step b1 includes: The supervisor obtains the leaked video conference video or picture and uploads it to the watermark detection system. The watermark detection system will extract the screen capture watermark information , and based on the conference number and the traceability identifier W for comparison, find all relevant content information from the blockchain, obtain the corresponding data from the InterPlanetary File System IPFS, locate the specific user, and calculate the hash value of the extracted watermark information to see if it is the same as the hash value of the watermark information stored on the chain : (10). (10).

[0016] Step b2 includes: The review department will first broadcast to other departments through a smart contract to request verification of the signature information and will share the evidence of leakage already in hand. The broadcast content is : (11), where is the address where the evidence is stored on the InterPlanetary File System IPFS, represents the hash storage of the evidence on the chain, represents the signature information that needs to be collaboratively traced, represents the timestamp, represents the required threshold (generally, the threshold needs to be greater than , and N represents the total number of people sharing the key), Indicates additional information.

[0017] When using the threshold mechanism for the tracking method, the final tracking key is aggregated. : (12), (13), (14), , (15), where represents to the power, is the temporary key or random number of the nth participant; represents to the power, is the random number generated for the nth participant, represents taking the modulus of all operation results with respect to the prime number th represents the minimum threshold value to be satisfied (the value is ), represents the weight of the nth participant in the j-threshold scheme; represents the secret share of the nth participant, represents after the tracking public key calculated by the hash function and the concatenated perturbation value of, represents the Lagrange interpolation coefficient, and are the public identifiers assigned to the t-th participant, and are not the same; PID decrypts using the private key to obtain the identifier, is the identification decryption function; After obtaining the user's public identity identifier PID, it will be compared with the screen capture watermark information. If PID is the same as the information in the watermark embedding, it means that the current user is a conference participant and the user has leaked the conference content during the conference.

[0018] The present invention also provides an electronic device, including a processor and a memory. The memory stores program code. When the program code is executed by the processor, the processor is caused to execute the steps of the method.

[0019] The present invention also provides a storage medium storing a computer program or instructions, which, when run on a computer, execute the steps of the above-mentioned method.

[0020] The present invention conducts a systematic analysis of the security issues of existing traceability and tracking models, and summarizes the potential security hazards existing in current traceability and evidence collection models, such as information leakage, tampering, or forgery by malicious participants. To solve the above problems, the present invention proposes a threshold traceable signature mechanism based on blockchain technology, aiming to construct a decentralized evidence collection and traceability model. The core of the present invention lies in realizing the effectiveness and security of information traceability and liability investigation in a multi-party participated dual-stream video conference by designing a ring signature algorithm with threshold traceability. This model can ensure the traceability and precise positioning of malicious behaviors under the premise of privacy protection. In addition, the present invention also focuses on studying the practicability and performance of this decentralized evidence collection and traceability model in the scenario of dual-stream video conferences, providing a new technical path for realizing secure and efficient video conference traceability.

[0021] Advantageous effects: By combining blockchain and smart contracts, the present invention realizes the immutability, transparency, and decentralization in the process of evidence collection and traceability, and supports automated evidence collection and traceability operations. To prevent malicious personnel from obtaining the identity information of participants from the chain, the present invention introduces a threshold traceable ring signature technology based on zero-knowledge proof, thus ensuring the anonymity of the information on the chain. In addition, the designed threshold mechanism can effectively prevent the single-point failure problem in a centralized system, and the traceability ensures that the true identity of the participant can be accurately traced when necessary. This solution successfully achieves a good balance between privacy protection and liability investigation. Description of the Drawings

[0022] Figure 1 Video conference privacy evidence collection and traceability framework.

[0023] Figure 2 Flow chart of video conference information going on-chain.

[0024] Figure 3 Flow chart of evidence collection and traceability based on blockchain.

[0025] Figure 4 Schematic diagram of the time consumption of each step of threshold traceable ring signature.

[0026] Figure 5 Schematic diagram of the reconstruction time consumption under different thresholds.

[0027] Figure 6 Performance comparison chart of signature tracing. Detailed Embodiments

[0028] The following further specifically describes the present invention in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become clearer.

[0029] An embodiment of the present invention provides a privacy traceability method for two-stream video conferencing based on blockchain, including: The traceability evidence collection solution for two-stream video conferencing based on traceable threshold ring signature is as Figure 1 shown. In the traceability evidence collection model, the design of the signature is the most critical link. Existing traceability evidence collection solutions usually adopt a centralized architecture, but this method has the following serious problems: single point of failure risk, insufficient transparency, lack of fairness, and weak privacy protection. This solution aims at the centralized architecture problem commonly existing in existing traceability evidence collection technologies and proposes a distributed traceability evidence collection model. In the traditional method, due to relying on a single centralized node for data storage and management, the system has problems such as single point of failure risk, insufficient transparency, lack of fairness, and weak privacy protection. To solve these problems, the present invention proposes a traceability evidence collection architecture based on blockchain. Through the blockchain technology with decentralization, immutability, and high transparency, single point of failure can be effectively avoided and the fairness and credibility of the system can be ensured.

[0030] In addition, in order to achieve a balance between on-chain information privacy protection and authorized access control, the present invention introduces a threshold traceable ring signature mechanism based on zero-knowledge proof. Through this mechanism, while ensuring the anonymity of information, accurate tracing of the responsible party can be achieved.

[0031] The traceability evidence collection model designed in this embodiment is mainly divided into two parts: information on-chain and traceability evidence collection. The following will introduce the specific design processes of the two parts in detail.

[0032] Information on-chain: As Figure 2 shown, during the video conferencing process, the audio and video data and related conference information are encrypted and signed through the threshold ring signature mechanism and then uploaded to IPFS (InterPlanetary File System) for storage and verification, and the key evidence will be uploaded to the blockchain. The smart contract is used to automate the management of data storage.

[0033] Data collection and preprocessing: The video conferencing terminal automatically collects the original information such as conference videos and documents, and embeds a traceability identifier W (anti-screen capture digital watermark) in the video frames. The watermark content W will be bound to the identities of the participants for subsequent leakage tracking: (1), wherein, is a hash function, , where Denote an arbitrary string length, and G denote an elliptic curve group. The overall meaning is to map an arbitrary binary input to an element in G. Denote the public identity identifier of user o Denote the unique identifier of the meeting Denote the timestamp of watermark generation; the traceability identifier Is an anti-screen capture digital watermark, the traceability identifier Will be bound to the identity of the attendee for subsequent leak tracking.

[0034] Information authentication: The system saves the information collected by the current user, encrypts it and uploads it to the InterPlanetary File System (IPFS), and returns , and the current user needs to use a threshold traceable ring signature algorithm based on zero-knowledge proof for To sign , Is the encrypted value of the user's public identity Is a non-interactive zero-knowledge proof (Non-Interactive Zero-Knowledge Proof, NIZK) generated using Schnorr signature and Okamoto protocol.

[0035] Upload of evidence chain: The system will encrypt the user's signature, the collected traceability identifier , the collected meeting videos, documents and other contents and upload them to the InterPlanetary File System (IPFS), calculate the hash values of the signature and the watermark, and finally upload the information to the blockchain to form: (2), Among them, Denote the meeting number; Cid, , Respectively denote the information stored by a certain user in the InterPlanetary File System (IPFS), the hash value of the signature, and the hash value of the watermark information. Through the double hash chain binding mechanism, the chain load can be effectively reduced, and the data integrity can be guaranteed, realizing a lightweight evidence storage and anti-tampering verification mechanism.

[0036] Traceability forensics: The process is as Figure 3 Shown. After obtaining the leaked picture information, by detecting the traceability identifier in the video or picture , compare it with the information stored on the chain , automatically trace and locate the leaked block point through the smart contract, and decrypt the real identity of the leaked party through multi-party cooperation.

[0037] Anomaly detection and trigger traceability: If the supervisor obtains the leaked video or picture of the video conference and uploads it to the system, the system will extract the screen capture watermark information from it. And compare it according to the meeting ID (MID) and watermark information in it, find all relevant content information from the blockchain, and obtain the corresponding data from the InterPlanetary File System IPFS to locate the specific user: (3), Multi-party collaboration information traceability: The review department will first broadcast to other departments through the smart contract, request to verify the signature information, and will share the leaked evidence it has mastered. The broadcast content is : (4), Among them is the address where the evidence is stored on the InterPlanetary File System IPFS, represents the hash storage of the evidence on the chain, represents the signature information that needs to be collaboratively traced, represents the threshold value required (set by the user himself), represents additional information.

[0038] In order to prevent the review agency from exposing the information of the people on the chain due to being attacked for some reason, a threshold mechanism is used for the tracking method, and multiple departments need to cooperate to aggregate the final tracking key : (5), (6), (7), Among them represents to the power of, is the temporary key or random number of the nth participant; represents to the power of, is the random number generated by the nth participant, represents that all operation results are modulo the prime number , th represents the lowest threshold value that needs to be satisfied, represents the weight of the nth participant in the j-threshold scheme; represents the secret share of the nth participant, represents the tracking public key obtained after being calculated by the hash function and The concatenated perturbation value, represents the Lagrange interpolation coefficient, and is the public identifier assigned to the nth participant, and are not the same; Then the PID is obtained: (8), Formula (5) is used to verify the correctness of the partial private key for tracing the private key provided by each department. Formulas (6) and (7) are for reconstructing the original key by the Lagrange interpolation method, and the present invention modifies it by adding a random perturbation term to prevent malicious nodes from cracking the private key through linear combination. When the number of malicious nodes is less than or equal to the threshold value, the private key cracking success rate of this scheme is 0.02%, while the success rate of the traditional Shamir threshold scheme is 12.7% under the same conditions; Formula (8) decrypts through the original key .

[0039] After obtaining the of the user, it will be compared with the screen capture watermark information. If the PID is the same as the information in the watermark embedding, it means that the current user is a participant in the meeting and has leaked the meeting content during the meeting. Finally, the decryption process and results are uploaded to the chain to form a complete forensic evidence chain.

[0040] In this embodiment, the gas consumption of the smart contract for traceability forensics is calculated, as shown in Table 1. In Figure 4 , the time consumption of each item of the threshold-based traceable ring signature algorithm in the present invention scheme when the threshold is 10 is shown. The main time consumption comes from the authentication of ring members and the construction of zero-knowledge proofs. Figure 5 shows the comparison of the time consumption of key sharing and reconstruction under different threshold values when the total number of shares is the same, i.e., 30, as Figure 6 shown. Compared with the existing tracing algorithms, the method of the present invention has better performance overhead.

[0041] Table 1

[0042]

[0043] In Table 2, some of the latest traceability and tracking technical solutions are compared, and the security attributes of these solutions are compared.

[0044] Table 2

[0045]

[0046] In a video conference, the content of the meeting in certain scenarios needs to be strictly confidential and any form of leakage is prohibited. The participants throughout the meeting process can be divided into three categories: the meeting initiator, the meeting participants, and the supervision department. It is assumed that the meeting initiator and the supervision department are to a certain extent trustworthy and honest, while the meeting participants may engage in dishonest behavior. The present invention aims to trace and trace the potential leakage behavior of the meeting participants, and at the same time balance transparency and privacy in the blockchain environment to ensure the effective protection of the security and privacy of personal information on the chain. The following is the specific implementation manner of the embodiments of the present invention.

[0047] Information on-chain: As Figure 2 shown, during the video conference process, the audio and video data and related meeting information are encrypted and signed through the threshold ring signature mechanism, and then uploaded to IPFS for storage and verification, and the key evidence will be uploaded to the blockchain. The smart contract is used to automate the management of data storage.

[0048] Parameter initialization: Each participant randomly generates a private key and calculates the public identity identifier . And all the public keys are stored on the chain. The system generates a pair of tracer keys , and through the Pedersen secret sharing scheme, is split into multiple shares, and the key share of each participant is verified for its validity through the commitment .

[0049] Information authentication: Generate the public parameters of the system, where is the pairing group, is the system generator, is the finite field, is the hash function, .

[0050] Save the video participation information of the current user, encrypt it and upload it to IPFS, and return , and the current user needs to sign it using the signature algorithm, , where represents to the power, is a random number; represents the public key of the tracer, and PID represents the user's public identity. Use Schnorr and Okamoto to generate a non-interactive zero-knowledge proof NIZK to form Ensure the validity of the signature and the security of the private key. The formula for generating the challenge value is as follows: (9), where represents the challenge value of the i-th member in the ring, represents the information to be signed, and respectively represent the Schnorr commitment generated by the (i - 1)-th member and the Okamoto commitment generated by the (i - 1)-th member in the ring; represents the exclusive OR operation.

[0051] Generate the NIZK of the members in the ring in sequence: Schnorr: (10), where represents the Schnorr commitment of the i-th member in the ring, z is a random number; represents the Schnorr response value of the i-th member in the ring, sk is the private key of the signer, is a random value.

[0052] Okamoto: (11), where is the Okamoto commitment of the i-th member in the ring, represents the public identity of the i-th member in the ring, is the Okamoto response value of the i-th member in the ring; is a random value.

[0053] Next, generate the verification information of the signer: Challenge value: (12), where represents the challenge value of the signer, R represents the number of members in the ring, represents the modulo operation, is a prime number; Schnorr: (13), Okamoto: (14), where , , , respectively represent the commitment value of the Schnorr signature generated by the signer, the response value of the Schnorr signature, the commitment value of the Okamoto signature, and the response value of the Okamoto signature.

[0054] Finally, a traceable ring signature is generated : (15), where respectively represent the commitment value, response value, and challenge value of the m-th member within the ring.

[0055] Evidence chain upload: The system will upload the user's signature to IPFS, calculate its hash value, and finally upload the information to the blockchain to form .

[0056] Among them, represents the meeting number; respectively represent the information stored by the k-th participant in IPFS, the hash value of the signature, and the hash value of the watermark information.

[0057] Traceability forensics: When a leaked picture or video is detected, the system compares the extracted watermark information with the information stored on the chain. The smart contract automatically identifies the leaking party and decrypts the real identity of the leaking party through multi-party cooperation.

[0058] Abnormal detection and trigger for traceability: The supervisor obtains the leaked video conference video or picture and uploads it to the system. The system will extract the screen capture watermark information from it . And compare it according to the meeting ID ( ) and the watermark information, find all relevant content information from the blockchain, and obtain the corresponding data from IPFS to locate the specific user.

[0059] Multi-party collaborative information traceability: The review department will first broadcast to other departments through the smart contract, request verification of the signature information, and share the evidence of leakage already in hand. The broadcast content is formula (4).

[0060] To prevent the review agency from being attacked for some reason and exposing the information of the people on the chain, the present invention uses a threshold mechanism for the tracking method, and multiple departments need to cooperate to aggregate the final tracking key . Finally, use the aggregated to decrypt the public identity information of the leaking person: (16), where PID is the public identity information, through Calculate the two values, such as Figure 6 As shown, compare the present invention with the existing tracing signature algorithms CLRS (Certificateless Ring Signature), ITAARS (Identity Traceable Anonymous Authentication Ring Signature), and TARSS (Traceable and Anonymous Authentication Ring Signature). Among them, CLRS avoids the certificate maintenance overhead of traditional PKI and reduces the time overhead; ITAARS relies on a third-party authorization agency for identity tracing and has a higher latency; TARSS requires multiple rounds of verification for tracing and has a high computational complexity. In the case of the same ring size, the tracing time of the non-interactive zero-knowledge proof used in the proposed solution of the present invention ( Figure 6 Ours in ) is better than the existing tracing algorithms.

[0061] After obtaining the user's PID, it will be compared with the watermark information extracted from the screen capture watermark. If the two are the same, it means that the current user is a conference participant and has leaked the conference content during the conference.

[0062] The present invention provides a method for privacy traceability of dual-stream video conferencing based on blockchain. There are many methods and ways to specifically implement this technical solution. The above description is only the preferred implementation mode of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be implemented using existing technologies.

Claims

1. A privacy traceability method for dual-stream video conferencing based on blockchain, characterized in that Including: Establishing a traceability and evidence collection model, where the traceability and evidence collection model includes information uploading to the chain and traceability and evidence collection; The information uploading to the chain includes: during a video conference, audio and video data and relevant conference information are encrypted and signed through a threshold ring signature mechanism, and then uploaded to the InterPlanetary File System (IPFS) for storage and verification. Key evidence will be uploaded to the blockchain; and a smart contract is used for automated data storage management; The traceability and evidence collection include: after obtaining the leaked picture information, detecting the traceability identifier W in the video or picture and comparing it with the information stored on the chain for comparison is a hash function , where represents an arbitrary string length, G represents an elliptic curve group means mapping any binary input to an element in G; automatically tracing and locating the leaked block point through a smart contract and decrypting the true identity of the leaking party.

2. The method according to claim 1, characterized in that, The specific steps of the information uploading to the chain are as follows: Step a1, data collection and preprocessing; Step a2, information authentication; Step a3, uploading of the evidence chain.

3. The method according to claim 2, wherein Step a1 includes: the video conference terminal automatically collects the original information including conference videos and documents, and embeds a traceability identifier W in the video frames; （1）， Among them, represents the public identity identifier of the user, represents the unique identifier of the meeting, represents the timestamp when the watermark is generated; the traceability identifier W is an anti-screen capture digital watermark, and the traceability identifier W will be bound to the identity of the participants for subsequent leak tracing.

4. The method according to claim 3, wherein Step a2 includes: saving the collected information of the current user, encrypting it and uploading it to the InterPlanetary File System (IPFS), and returning an address information , performing hash encryption on the address information obtained from the InterPlanetary File System (IPFS); where represents the storage address in the InterPlanetary File System (IPFS) where the x-th piece of information collected by the current user is stored; For the current user, use the threshold traceable ring signature algorithm based on zero-knowledge proof to perform signature to obtain , is the encrypted value of the user's public identity, is the non-interactive zero-knowledge proof generated using Schnorr signature and Okamoto protocol; The specific threshold traceable ring signature algorithm includes: Input security parameter , is the security strength, and through , generate the public parameters of the system , where is the pairing group, is the system generator, represents the bilinear mapping, is the finite field; represents the public parameters pp of the system initialized by the security parameter ; Save the video conferencing information of the current user, encrypt it and upload it to the InterPlanetary File System (IPFS), and return , the current user needs to use a signature algorithm for to sign , where means to the power of , and is a random number; represents the public key of the tracker, and PID represents the user's public identity; use Schnorr and Okamoto to generate non-interactive zero-knowledge proofs , and the formula for generating the challenge value is: （2）， Among them represents the challenge value of the members within the i-th ring, represents the information to be signed, and respectively represent the Schnorr commitment generated by the members within the (i - 1)-th ring and the Okamoto commitment generated by the members within the (i - 1)-th ring; represents the exclusive OR operation; Successively generating non-interactive zero-knowledge proofs for the members within the ring; （3）， where represents the Schnorr commitment of the $i$-th ring member, and $z$ is a random number; represents the Schnorr response value of the $i$-th ring member, $sk$ is the private key of the signer, is a random value; （4）， wherein is the Okamoto commitment of the i-th member within the ring, represents the public identity of the i-th member within the ring, is the Okamoto response value of the i-th member within the ring; Next, generating the verification information of the signer; Calculating the challenge value; （5）， Among them represents the challenge value of the signer, R represents the number of members in the ring, represents modulo operation, is a prime number; （6）， （7）， Among them , , , respectively represent the commitment value of the Schnorr signature generated by the signer, the response value of the Schnorr signature, the commitment value of the Okamoto signature, and the response value of the Okamoto signature; Finally, generate a traceable ring signature : （8）， Among them, respectively represent the commitment value, response value, and challenge value of the members within the m-th ring; Final combined member signature information( ).

5. The method according to claim 4, characterized in that, Step a3 includes: encrypting the user's signature, the collected traceability identifier W, the collected conference videos and documents, and uploading them to the InterPlanetary File System (IPFS), calculating the hash values of the signature and the traceability identifier, and finally uploading the information to the blockchain to form an evidence chain M; （9）， Among them, respectively represent the information stored by a user in the InterPlanetary File System (IPFS), the hash value of the signature, and the hash value of the watermark information. The value range of k is from 1 to H1, and H1 represents the number of participants in the meeting.

6. The method according to claim 5, characterized in that The specific steps of the traceability and evidence collection are as follows: Step b1, anomaly detection and triggering of traceability; Step b2, multi-party collaborative information traceability.

7. The method according to claim 6, wherein Step b1 includes: The supervisor obtains the leaked video conference video or picture and uploads it to the watermark detection system, which will extract the screen capture watermark information , and compares it according to the meeting number and the traceability identifier W, searches for relevant content information on the blockchain, obtains the corresponding data from the InterPlanetary File System IPFS, and calculates the hash value of the extracted watermark information is the same as the hash value of the watermark information stored on the chain , and locates the specific user:​ （10）。 8. The method according to claim 7, wherein Step b2 includes: The examining department will first broadcast through the smart contract, request verification of the signature information, and share the evidence of leakage it has mastered. The content of the broadcast is : （11）， Among them is the address where the evidence is stored on the InterPlanetary File System (IPFS), represents the hash storage of the evidence on the chain, represents the signature information that requires collaborative tracking, represents the timestamp, represents the required threshold, represents additional information; Use a threshold mechanism when using the tracking method to aggregate the final tracking key : （12）， (13)， （14）， ， （15）， Among them denotes to the power, is the temporary key or random number of the nth participant; denotes to the power, is the random number generated for the nth participant, denotes taking the modulus of all operation results with respect to the prime number , th represents the lowest threshold value that needs to be satisfied, represents the weight of the nth participant under the j-threshold scheme; denotes the secret share of the n-th participant, denotes the concatenated perturbation value obtained by computing the tracing public key through the hash function and ; denotes the Lagrange interpolation coefficient, and is the public identifier assigned to the t-th participant, and are not the same; The PID is decrypted by the private key to obtain the identifier , which is the identification decryption function; ​ After obtaining the public identity identifier PID of the user, it will be compared with the screen capture watermark information. If PID is the same as the information in the watermark embedding, it means that the current user is a conference participant and the user leaked the conference content during the participation process.

9. An electronic device, characterized in that, Including a processor and a memory, where the memory stores program code, and when the program code is executed by the processor, the processor executes the steps of the method according to any one of claims 1 to 8.

10. A storage medium, characterized in that, Storing a computer program or instruction, and when the computer program or instruction runs on a computer, it executes the steps of the method according to any one of claims 1 to 8.

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