Multi-modal digital asset transaction and trusted delivery method and system based on distributed identity and relay-free cross-chain

Abstract

The invention relates to a distributed identity and relay-free cross-chain-based multi-modal digital asset transaction and trusted delivery method and system. The method comprises the following steps: a user registers on a certain block chain of a block chain ecosystem to obtain a corresponding DID identity; different token file structures are designed for digital assets with different modalities, different privacy protection types and different data access frequencies, and hierarchical data storage of the multi-modal digital assets is realized, so that casting of the digital assets is completed; the user carries out digital asset transaction; and delivering the multi-modal digital assets according to different confidentiality requirements and access frequencies. According to the invention, a feasible innovative scheme design is provided for multi-modal digital asset circulation transaction in a cross-chain scene, the actual application scene of the block chain is further expanded, a data island phenomenon in a multi-block chain system is broken, and asset circulation between the block chains and prosperous development of an ecological system can be promoted.

Description

Technical Field

[0001] This invention belongs to the field of blockchain technology, specifically relating to a method and system for multimodal digital asset transactions and trusted delivery based on distributed identity and relay-free cross-chain. Background Technology

[0002] In a narrow sense, blockchain is a chain-like data structure that combines data blocks sequentially according to time, and is a distributed ledger that is cryptographically guaranteed to be immutable and unforgeable. In a broad sense, blockchain technology utilizes a chain-like data structure to verify and store data, uses distributed node consensus algorithms to generate and update data, employs cryptography to ensure the security of data transmission and access, and utilizes smart contracts composed of automated script code to program and manipulate data—a novel distributed infrastructure and computing paradigm.

[0003] Decentralized Identifier (DID) technology is a revolutionary approach to digital identity management that enables individuals and organizations to autonomously create and manage their own identity information without relying on centralized intermediaries. DID technology utilizes blockchain and distributed ledger technology to achieve autonomous control and secure verification of identity data. Its key features include self-management, privacy protection, interoperability, security, and decentralization. Furthermore, DID systems can interoperate between different blockchains, supporting cross-chain authentication and enhancing system compatibility and flexibility. Through cryptographic techniques, DID ensures the security and immutability of identity information; each DID is associated with a unique identifier and public-private key pair, preventing identity theft. DID technology has broad application prospects in digital identity authentication, IoT device management, and decentralized applications, providing a secure, efficient, and privacy-preserving new approach to future digital identity management.

[0004] Cross-chain technology is an innovative technology designed to enable interoperability between different blockchain networks. It solves the problem of data and asset silos between blockchain networks, allowing different blockchains to communicate, share information, and transfer assets. Through cross-chain technology, various blockchain networks are no longer isolated systems but can work together to form a larger, more integrated blockchain ecosystem. Key features of cross-chain technology include interoperability, asset transfer, smart contract interoperability, security and decentralization, and scalability.

[0005] Digital assets are a form of asset created and managed based on digital and blockchain technologies, including cryptocurrencies, tokens, digital artwork, and virtual real estate. Unlike traditional assets, digital assets are characterized by decentralization, transparency, security, and globalization. They enable trusted peer-to-peer transactions through blockchain technology, eliminating the need for intermediaries, reducing transaction costs, and increasing transaction speed.

[0006] Patent "CN114997867A: Multi-modal Delivery System and Method for Data Elements Based on Blockchain and Privacy Computation" proposes a multi-modal delivery system for data elements based on blockchain and privacy computing. This patent focuses on the sharing of privacy data and the privacy computing of related data, and its application scenario is a single blockchain. However, the proposed technology is not suitable for the transaction and trusted delivery of digital assets in cross-chain scenarios.

[0007] Patent CN114077744A: Blockchain Universal Asset Processing Method, Apparatus, Device, and Storage Medium proposes a blockchain universal asset processing method. This patent focuses on a two-layer key encrypted digital asset sharing scheme based on proxy re-encryption technology. However, the technology proposed in this patent is not suitable for digital asset delivery scenarios with multiple asset types, and it does not address digital asset transaction processes or cross-chain scenarios; therefore, it cannot be applied to the scenarios described in this patent.

[0008] Patent "CN115865531A: A Method for Authorizing Digital Assets by Proxy Re-encryption" proposes a method for authorizing digital assets by proxy re-encryption. The patent focuses on providing a feasible proxy re-encryption technology to re-encrypt the data contained in encrypted digital assets, with the aim of achieving data sharing. However, the proposed technology is not suitable for digital asset delivery scenarios with multiple asset types, and it is not designed for digital asset trading processes and cross-chain scenarios; therefore, it cannot be applied to the scenario described in this patent. Summary of the Invention

[0009] The technical problem to be solved by this invention is:

[0010] 1. Currently, the trend is towards a future development where multiple blockchains coordinate and cooperate with each other in a manner similar to Polkadot or Cosmos to form a unified blockchain ecosystem. This has created a demand for users on different chains to conduct transactions and share data. However, there is currently a lack of efficient solutions for mutual verification of user identities between different chains, and existing cross-chain solutions based on relay chains or involving trusted third parties are cumbersome and carry the risk of centralization.

[0011] 2. Currently, for digital asset transactions based on blockchain technology, there is no corresponding digital asset structure designed for multimodal data such as text, audio, video, and images, as well as the different privacy protection requirements of different data types; the transaction process for digital assets lacks solutions for cross-chain scenarios, and the delivery process for digital assets lacks a holistic framework solution design that incorporates privacy protection requirements.

[0012] The technical solution adopted in this invention is as follows:

[0013] A multimodal digital asset transaction and trusted delivery method based on distributed identity and relay-free cross-chain includes the following steps:

[0014] Users register on a blockchain within the blockchain ecosystem to obtain a corresponding DID identity, and the user's DID is recorded in the DID management contract of the corresponding blockchain;

[0015] Different token file structures are designed for digital assets with different modalities, different privacy protection types, and data access frequencies. Multi-modal digital asset data is stored in a hierarchical manner by combining on-chain and off-chain storage. Users send the data required for the corresponding type of token file structure to the digital asset management contract to complete the minting of digital assets.

[0016] Users can trade digital assets through two different types of smart contracts: auction contracts and order contracts, as well as through cross-chain user participation and local chain user participation.

[0017] Deliver multimodal digital assets according to different confidentiality requirements and access frequencies to ensure the security and trustworthiness of the delivery process.

[0018] Furthermore, the format of the user DID is as follows:

[0019] did: chainName: userName: authLevel

[0020] Where chainName represents the unique identifier of the blockchain to which the new user is about to join in the blockchain ecosystem; userName represents the unique identifier of the new user; authLevel represents the permission level of the new user; the identifier of user DID is generated, allocated and recorded by the DID management contract on the target blockchain to which the user wants to join based on the registration request submitted by the user containing the user's public key.

[0021] Furthermore, the multimodal digital assets include text, images, audio, and video; the token file structure supports digital assets of different modal types, and different file compression methods are used to compress the asset data size for different modal digital assets.

[0022] Furthermore, the digital asset transactions adopt an event-driven, relay-free cross-chain processing scheme based on a cross-chain gateway. This scheme achieves cross-chain transaction processing while ensuring transaction atomicity, without the need for a trusted third party. Suppose a user on chain A wants to participate in an auction contract or order book contract on chain B. The event-driven, relay-free cross-chain processing scheme based on a cross-chain gateway includes the following steps:

[0023] 1) Initiate a call to the asset management contract deployed on Chain A. The parameters of the call are <did, TChainName, Address, ID, value>, where did represents the user's distributed identity, TChainName represents the unique identifier of the target chain of this cross-chain request initiated by the user in the current blockchain ecosystem, ID represents the number of the multimodal digital asset that the current user wants to bid or buy in the auction contract or order contract, and value represents the bid or purchase price proposed by the current user.

[0024] 2) The asset management contract locks the corresponding assets based on the value in the call and triggers the corresponding cross-chain event;

[0025] 3) After the cross-chain gateway of chain A detects the corresponding cross-chain event, it verifies whether the locking transaction that triggered the event was successfully executed; if it was successfully executed, it generates a proof for the corresponding event and forwards the cross-chain request to the corresponding target chain.

[0026] 4) After receiving a cross-chain request from the cross-chain gateway of chain A, the cross-chain gateway of chain B first verifies the identity proof and locking proof attached to the cross-chain request. After the verification is successful, it initiates the corresponding minting transaction and call request to the temporary contract.

[0027] 5) After receiving the call, the temporary contract initiates a call to the corresponding target contract according to the call parameters. In this process, the temporary contract is regarded as the agent of the cross-chain user on chain B.

[0028] 6) After a cross-chain user initiates a purchase or bid and succeeds, the digital assets and funds are first transferred to the delivery contract for further processing, following the same processing logic as a successful bid by a user on this chain. Secondly, when the delivery contract discovers that the delivery recipient is a cross-chain user, it will trigger the corresponding cross-chain event.

[0029] 7) Chain B's cross-chain gateway continuously monitors cross-chain events on Chain B;

[0030] 8) When the cross-chain gateway on Chain B detects a cross-chain event triggered by the delivery contract, it generates proof of the successful bidding or purchase transaction of the cross-chain user on Chain B, generates a cross-chain request, and forwards it to the cross-chain gateway of the corresponding chain; the format of the cross-chain request is: <did,TChainName,Address,ID,value,Proof tx >, where Proof tx Proof of successful transaction execution;

[0031] 9) After receiving a cross-chain request from chain B, the cross-chain gateway of chain A first verifies the Proof. txAfter verifying the legality and correctness of the asset management contract, the cross-chain gateway of Chain A initiates a call to the asset management contract on Chain A to permanently lock up the pledged funds of users on Chain A.

[0032] Furthermore, when a cross-chain asset transaction request fails, it is handled according to the following steps:

[0033] 1) If a pending contract transaction fails, the funds are returned to the temporary contract when the transaction fails; if a successful bid in an auction contract is replaced by a higher price, the auction contract initiates a call to the temporary contract and returns the funds to the temporary contract.

[0034] 2) When a fund return event occurs during the temporary contract call, if the source of funds is a cross-chain user, the temporary contract will destroy the corresponding funds, i.e., transfer them to the black hole account, and trigger the corresponding cross-chain event.

[0035] 3) After Chain B's cross-chain gateway detects a cross-chain event triggered by a refund in the temporary contract, it destroys the temporary contract to generate proof of the transaction and generates a corresponding cross-chain request. The format of this request is: <did, TChainName, Address, ID, value, Proof> burn >, where Proof burn It serves as proof that the funds corresponding to the temporary storage contract have been destroyed;

[0036] 4) When the cross-chain gateway of chain A receives the relevant cross-chain request, it first verifies the Proof. burn After verifying the legality and correctness of the asset management contract, the cross-chain gateway of Chain A initiates a call to the asset management contract on Chain A to unlock the pledged funds of users on Chain A.

[0037] 5) Chain A's asset management contract will return the corresponding funds to the user who initially initiated the call, based on the call from the cross-chain gateway.

[0038] Furthermore, the delivery of multimodal digital assets based on different confidentiality requirements and access frequencies includes:

[0039] For the delivery of multimodal digital assets without confidentiality requirements, the delivery contract directly transfers the corresponding purchase funds to the seller of the corresponding asset, and then transfers ownership of the multimodal digital asset; if the buyer is on the current chain, the transfer is carried out directly; if the buyer is a cross-chain user, the transfer is transferred to a temporary storage contract for holding.

[0040] For the delivery of multimodal data assets with privacy protection requirements and high access frequency, the steps include: 1) After entering the delivery phase, the delivery contract sets a timer for the delivery instance. The asset seller uploads a re-encryption key generated based on the buyer's DID public key before the timer countdown; otherwise, the transaction is considered a failure, and the funds and multimodal digital assets are returned; 2) After the asset seller uploads the re-encryption key generated based on the buyer's DID public key, the delivery contract enters a challenge period. If a user submits proof of the illegality of the re-encryption key during the challenge period, the transaction is considered a failure, and the funds and multimodal digital assets are returned. 3) After the challenge period ends, the delivery contract transforms the encrypted ciphertext stored in the multimodal digital asset based on the re-encryption key submitted by the asset seller, obtaining the ciphertext encrypted using the buyer's DID public key. Then, the delivery contract destroys the original multimodal digital asset and creates a new multimodal digital asset based on the new ciphertext and the original digest; 4) The delivery contract transfers the corresponding purchase funds to the seller of the corresponding asset and transfers ownership of the multimodal digital asset. If the buyer is located on the current chain, the transfer is performed directly; if the buyer is a cross-chain user, the transfer is made to a temporary storage contract for holding.

[0041] For the delivery of multimodal data assets with privacy protection requirements and low access frequency, the steps include: 1) The asset seller needs to deliver the original data off-chain with the asset buyer; 2) After receiving the original data from the asset seller, the asset buyer calculates the summary of the received data. If it matches the summary recorded in the digital asset corresponding to the data, the buyer submits a confirmation of successful asset delivery. If the buyer is on the same chain, the process jumps directly to step 5). If the buyer is on a cross-chain, the buyer initiates a cross-chain confirmation request to the asset management contract of the chain on which the asset is located, and the asset management contract triggers the corresponding cross-chain event; 3) The cross-chain gateway of chain A continuously listens for the corresponding cross-chain events, including cross-chain events triggered by the asset management contract; 4) When the cross-chain gateway of chain A listens for a cross-chain event triggered by the asset management contract, it generates and forwards the corresponding cross-chain request to the cross-chain gateway of the target chain. The format of the request is: <did, TChainName, Address, ID, Proof> did Proof c >, where ID represents the unique number of this transaction in the delivery contract, Proof did It is a proof of the legitimacy and validity of the user's identity on Chain A. c This involves providing a zero-knowledge proof for the user of Chain A regarding the data already received via off-chain delivery; 5) After receiving a cross-chain request from the cross-chain gateway of Chain A, the cross-chain gateway of Chain B verifies the Proof in the request. did and Proof cThe validity and legality of the transaction are verified. After the verification is passed, the cross-chain gateway initiates confirmation to the delivery contract. The buyer in this chain also initiates confirmation to the delivery contract after acceptance. 6) The delivery contract transfers the corresponding purchase funds to the seller of the corresponding asset and transfers the ownership of the multimodal digital asset. If the buyer is located in the current chain, the transfer is carried out directly. If the buyer is a cross-chain user, the transfer is transferred to the temporary storage contract for holding.

[0042] Furthermore, the following steps are used to achieve cross-chain extraction and transfer of multimodal digital assets:

[0043] 1) Cross-chain users initiate asset withdrawal calls to the asset management contract of this chain. The format of the call is <did, TChainName, AID>, where AID is the unique identifier of the target asset to be withdrawn by the user.

[0044] 2) After the asset management contract receives the request, it will trigger a corresponding cross-chain event, which will be listened to and captured by the cross-chain gateway of chain A;

[0045] 3) After Chain A's cross-chain gateway detects a relevant cross-chain event, it generates an identity certificate and forwards the corresponding cross-chain request to the target chain's cross-chain gateway. The format of this request is <did, TChainName, AID, Proof>. did >, where Proof did It serves as proof of the legitimacy and validity of the identity of the user in Chain A;

[0046] 4) After receiving a cross-chain request from chain A, the cross-chain gateway of chain B checks the Proof in the request. did Perform verification, and once verification is successful, initiate a call to the temporary contract;

[0047] 5) After receiving a request to withdraw assets, the temporary storage contract first verifies whether the holder of the assets to be withdrawn is consistent with the DID identity of the user who initiated the withdrawal request. If they are consistent, the asset is locked and the corresponding cross-chain event is triggered.

[0048] 6) Chain B's cross-chain gateway listens to the cross-chain event described in step 5);

[0049] 7) Chain B's cross-chain gateway generates proof of the locked transaction that triggered the cross-chain event and forwards the corresponding cross-chain request to Chain A's cross-chain gateway.

[0050] 8) After receiving a cross-chain request from chain B, the cross-chain gateway of chain A first verifies the validity and legality of the locked transaction proof. If the verification is successful, the corresponding assets are minted into the asset management contract.

[0051] 9) The asset management contract transfers the corresponding assets to the user, realizing the change of ownership of multimodal digital assets and triggering the corresponding cross-chain events;

[0052] 10) Chain A's cross-chain gateway listens to the cross-chain event described in step 9);

[0053] 11) The cross-chain gateway of chain A generates proof of the asset transfer transaction and forwards the corresponding cross-chain request to the cross-chain gateway of chain B.

[0054] 12) After receiving a cross-chain request from chain A, the cross-chain gateway of chain B first verifies the validity and legality of the asset transfer transaction proof. After the verification is successful, it initiates a destruction request to the temporary contract.

[0055] 13) After receiving a destruction request from the cross-chain gateway, the temporary storage contract will release the corresponding original assets from the locked state and destroy them after verifying the validity of the proof.

[0056] A multimodal digital asset transaction and trusted delivery system based on distributed identity and relay-free cross-chain technology, comprising:

[0057] The user registration module is used to register users on a blockchain in the blockchain ecosystem to obtain the corresponding DID identity, and to record the user DID in the DID management contract of the corresponding blockchain;

[0058] The digital asset minting module is used to design different token file structures for digital assets with different modalities, different privacy protection types, and data access frequencies. It also achieves hierarchical data storage for multimodal digital assets by combining on-chain and off-chain storage. Users send the data required for the corresponding type of token file structure to the digital asset management contract to complete the minting of digital assets.

[0059] The digital asset trading module is used by users to trade digital assets. It includes two different types of smart contracts: auction contracts and order contracts, as well as two ways for users to participate: cross-chain users and users of the same chain.

[0060] The digital asset delivery module is used to deliver multimodal digital assets according to different confidentiality requirements and access frequencies, ensuring the security and trustworthiness of the delivery process.

[0061] The beneficial effects of this invention are as follows:

[0062] 1. This patent presents a design scheme for a distributed user identity (DID) in a multimodal digital asset trading scenario within a blockchain ecosystem comprised of multiple blockchains. This scheme enables mutual authentication of user identities across different blockchains, offering a more unified and standardized identity format compared to traditional solutions, and significantly improving verification efficiency during asset transactions. Furthermore, this patent provides a relay-free cross-chain interaction protocol based on a cross-chain gateway. This protocol enables cross-chain interaction between different blockchains without introducing a trusted third party, reducing message complexity and avoiding the risks of centralization compared to traditional solutions.

[0063] 2. This patent designs corresponding digital asset structures and digital asset compression and storage methods for multimodal data and different data with different privacy protection requirements. It also provides a detailed innovative solution design for the transaction and trusted delivery of multimodal digital assets in cross-chain scenarios. Under the premise of ensuring the atomicity of cross-chain transactions, it realizes the free, trusted and efficient circulation and transaction of multimodal digital assets on different chains, providing a feasible solution design for the circulation of multimodal digital assets under Web3.0. Attached Figure Description

[0064] Figure 1 This is a flowchart of the steps of the method of the present invention.

[0065] Figure 2 This is a flowchart of the new user registration DID process.

[0066] Figure 3 It refers to the token file structure design corresponding to digital assets with different modalities and storage methods.

[0067] Figure 4 This is a schematic diagram of the digital asset creation process.

[0068] Figure 5 This is a diagram illustrating a user's request to initiate a digital asset transaction.

[0069] Figure 6 This is a diagram illustrating how users of this blockchain participate in multimodal digital asset auctions.

[0070] Figure 7 This is a diagram illustrating how users of this blockchain participate in multimodal digital asset order placement.

[0071] Figure 8 This is a diagram illustrating cross-chain user participation in multimodal digital asset auctions and order placement.

[0072] Figure 9 This is a diagram illustrating how cross-chain user asset transaction requests are handled when they fail.

[0073] Figure 10 It is a delivery process for multimodal digital assets without confidentiality requirements.

[0074] Figure 11 It is a delivery process for multimodal data assets with privacy data protection requirements and small data volume.

[0075] Figure 12 It is the delivery process for data assets with privacy protection needs and large data volumes.

[0076] Figure 13 It is a cross-chain user asset withdrawal process. Detailed Implementation

[0077] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0078] The overall process of the multimodal digital asset transaction and trusted delivery method based on distributed identity and relay-free cross-chain in this invention is as follows: Figure 1 As shown, this is a full lifecycle framework for digital asset transactions and trusted delivery based on distributed identity and relay-free cross-chain technology, supporting multimodal digital assets and enabling on-chain and off-chain collaboration. The method includes the following steps:

[0079] Step 1: This patent targets a unified blockchain ecosystem similar to Polkadot or Cosmos, composed of multiple blockchains. Therefore, the first step requires users joining a particular blockchain within this ecosystem to register on that blockchain and obtain a corresponding DID identity. The user's DID is then simultaneously recorded in the DID management contract of that blockchain. The user DID design format is as follows:

[0080] did: chainName: userName: authLevel

[0081] Where chainName represents the unique identifier of the blockchain the new user is about to join within the blockchain ecosystem; userName represents the unique identifier of the new user; and authLevel represents the new user's permission level. These DID identifiers are generated, allocated, and recorded by the DID management contract on the target blockchain the user wants to join, based on the registration request submitted by the new user containing the user's public key. The specific process is as follows: Figure 2 As shown, it includes the following steps:

[0082] 1) Users generate public key pk and private key sk using a unified asymmetric encryption algorithm;

[0083] 2) The user initiates a DID registration request call to the DID management contract on the target blockchain to which they want to join. The call parameters include the user's public key.

[0084] 3) The DID management contract generates a corresponding DID identity for the user based on the user's public key and returns it to the user who initiated the call.

[0085] Step Two: This step mainly introduces the uploading of data to generate digital assets. The carrier of these digital assets is designed in this patent as a non-fungible token similar to an ERC-721 type token, and different token file structure designs are provided for digital assets with different privacy protection types and asset data access frequencies. Furthermore, a combination of on-chain and off-chain storage is used to achieve hierarchical storage of multimodal digital asset data. The aforementioned token file structure design supports different modalities of digital assets, including text, images, audio, and video, and different file compression methods are provided for different modalities to compress asset data size and reduce data size. For text modal digital assets, the Deflate algorithm is used for compression; for image modal digital assets, models such as autoencoders and variational autoencoders (VAEs) are introduced, utilizing deep learning technology for image compression; for audio modal digital assets, the SoundStream algorithm is used for compression; and for video modal digital assets, the Deep VideoCompression algorithm is used, employing a neural network model for inter-frame and intra-frame compression, achieving efficient compression by learning the temporal and spatial characteristics of the video.

[0086] The specific token file structure design for digital assets with different modalities and storage methods is as follows: Figure 3 As shown:

[0087] 1) For digital assets that do not require privacy data protection, the full amount of original data is directly stored in the data section of the token file.

[0088] 2) For data assets that require privacy data protection and high-frequency access, the token file stores the ciphertext of the original data encrypted with the asset minter's public key and the data digest generated from the complete original data.

[0089] 3) For data assets that have privacy data protection needs and low access frequency, only the data summary generated from the complete original data and the address of off-chain storage are stored in the token file.

[0090] Afterwards, users send the data required for the corresponding token structure to the digital asset management contract according to their needs, thus completing the minting of the corresponding digital asset. The current user will then become the holder of that digital asset. This process has... Figure 4 As shown:

[0091] Step 3: Users can choose to sell their digital assets based on their actual needs, i.e., conduct digital asset transactions. This patent designs two different types of smart contracts: auction and fixed-price order trading. Users can flexibly choose between auction-based digital asset trading and fixed-price order trading based on their actual needs, transferring the digital assets they intend to sell into the corresponding contract to create a corresponding transaction instance. Each instance has a unique ID. The specific process is as follows. Figure 5 As shown.

[0092] Step 4: Other users bid for the multimodal digital assets they wish to purchase in the auction contract or purchase the multimodal digital assets for sale in the order book contract according to their needs. In this step, this patent will discuss two categories: cross-chain user participation and local chain user participation.

[0093] Firstly, regarding scenarios involving users of this blockchain, this patent design includes participating in auction contracts and participating in order placement contracts. The process for users of this blockchain to participate in auction contracts is as follows: Figure 6 As shown, it includes the following steps:

[0094] 1) A user initiates a bidding request for an auction of a specific multimodal digital asset that is currently running in the auction contract. The essence of this request is a user call to the contract. The parameters of this call are <ID, value>, where ID represents the number of the auction instance that the current user wants to participate in, and value represents the bidding price proposed by the current user.

[0095] 2) After receiving a request from a user, the auction contract will verify the validity of the request. This process includes: verifying whether the auction instance corresponding to the ID parameter is in a bidable state, and verifying whether the price bid by the user is higher than the current price.

[0096] 3) If the above legality verification fails, the user's submitted bidding request transaction will be rolled back and the bidding will be considered a failure.

[0097] 4) If the validity verification passes, the user successfully bids for the auction instance represented by the current ID. If there are previous bidders, their bid funds will be refunded. If the current user remains the highest bidder until the end of the auction, the corresponding funds and multimodal digital assets will be transferred to the delivery contract for further processing.

[0098] The design for users of this chain participating in order placement contracts will now be introduced, with the specific process as follows: Figure 7 As shown, it includes the following steps:

[0099] 1) A user initiates a purchase request for a specific multimodal digital asset that is being sold in the order book. The essence of this request is a user call to the contract. The parameters of this call are <ID, value>, where ID represents the number of the multimodal digital asset that the user wants to buy in the order book, and value represents the purchase price proposed by the user.

[0100] 2) After receiving a request from a user, the order book contract will verify the validity of the request. This process includes: verifying whether the instance corresponding to the ID parameter is in a purchaseable state, and verifying whether the price submitted by the user is equal to or higher than the order price of the corresponding asset.

[0101] 3) If the above legality verification fails, the purchase request submitted by the user will be rolled back and the purchase will be considered a failure.

[0102] 4) If the legality verification is successful, the user will successfully purchase the order instance represented by the current ID. The corresponding funds and corresponding multimodal digital assets will then be transferred to the delivery contract for further processing.

[0103] This section describes the process for cross-chain users participating in auction contracts and order placement contracts. Within this process, this patent also presents an event-driven, relay-free cross-chain processing solution based on a cross-chain gateway. This solution, through a two-phase lock, can process cross-chain transactions while ensuring transaction atomicity, and it eliminates the need for a trusted third party, thus representing a decentralized cross-chain processing solution. The specific process is as follows: Figure 8 As shown, it includes the following steps:

[0104] 1) If a user on Chain A wishes to participate in an auction contract or order book contract on Chain B, they must first initiate a call to the asset management contract deployed on Chain A. The parameters for this call are <did, TChainName, Address, ID, value>. Here, didi represents the user's distributed identity generated in step one; TChainName represents the unique identifier of the target chain in the current blockchain ecosystem for this cross-chain request; ID represents the number of the multimodal digital asset the user wants to bid on or purchase within the auction contract or order book contract; and value represents the bid or purchase price offered by the user.

[0105] 2) After a user on Chain A initiates a call to the asset management contract, the asset management contract will lock the corresponding asset based on the value in this call and trigger the corresponding cross-chain event. The cross-chain gateway on Chain A will then listen for this event.

[0106] 3) After Chain A's cross-chain gateway detects the corresponding cross-chain event, it verifies whether the locking transaction that triggered the event was successfully executed. If successful, it generates a proof for the corresponding event and forwards the cross-chain request to the corresponding target chain. The format of the forwarding request is: <did, TChainName, Address, ID, value, Proof> did Proof lock >, where Proof did It is the cross-chain gateway of Chain A that proves the legitimacy and validity of the user's identity. lock This serves as proof of the successful execution of the locked transaction by the cross-chain gateway of Chain A.

[0107] 4) After receiving a cross-chain request from the cross-chain gateway of Chain A, the cross-chain gateway of Chain B will first verify the identity and lock proof attached to the cross-chain request. Upon successful verification, it will initiate the corresponding minting transaction and call request to the temporary contract. The format of this call request is <did, SChainName, Address, ID, value>, where SChainName represents the initiating chain of this cross-chain call.

[0108] 5) After receiving a call, the temporary contract will initiate a call to the corresponding target contract based on the call parameters. This process can be viewed as the temporary contract acting as an agent for cross-chain users on chain B, with the remaining logic being the same as for users on this chain. The handling process for execution failures will be described below.

[0109] 6) If a cross-chain user's purchase or bid is successful, the digital assets and funds will first be transferred to the delivery contract for further processing, following the same processing logic as a successful bid from a local chain user. Secondly, when the delivery contract detects that the delivery recipient is a cross-chain user, it will trigger a corresponding cross-chain event, which will include the following parameters: <did, SChainName, Address, ID, value>.

[0110] 7) Chain B's cross-chain gateway will continuously monitor cross-chain events on Chain B.

[0111] 8) When the cross-chain gateway on Chain B detects a cross-chain event triggered by the delivery contract, it will generate proof for the successful bidding or purchase transaction of the cross-chain user on Chain B, and generate a cross-chain request, which will be forwarded to the cross-chain gateway of the corresponding chain. The format of the cross-chain request is: <did, TChainName, Address, ID, value, Proof> tx >, where Proof tx This serves as proof that the aforementioned transaction was successfully executed.

[0112] 9) After receiving a cross-chain request from chain B, the cross-chain gateway of chain A will first verify the Proof. tx The legality and correctness of the transaction are verified. Once verified, the cross-chain gateway of Chain A will initiate a call to the asset management contract on Chain A to permanently lock the staked funds of users on Chain A.

[0113] The following section describes how to handle failed cross-chain asset transaction requests, with the specific process as follows: Figure 9 As shown, it includes the following steps:

[0114] 1) If a pending order fails, the funds will be returned to the temporary contract when the transaction fails. If a successful bid in an auction contract is replaced by a higher price, the auction contract will invoke the temporary contract to return the funds to the temporary contract.

[0115] 2) When a fund return event occurs during the temporary contract call, if the source of funds is a cross-chain user, the temporary contract will destroy the corresponding funds, i.e., transfer them to the black hole account, and trigger the corresponding cross-chain event.

[0116] 3) After Chain B's cross-chain gateway detects a cross-chain event triggered by a refund in the temporary contract, it will destroy the temporary contract to generate proof of the transaction and generate a corresponding cross-chain request in the format: <did, TChainName, Address, ID, value, Proof> burn >, where Proof burn It serves as proof that the temporary storage contract has destroyed the corresponding funds.

[0117] 4) When the cross-chain gateway of chain A receives the relevant cross-chain request, it will first verify the Proof. burn The legality and correctness of the transaction are verified. After successful verification, the cross-chain gateway of Chain A will initiate a call to the asset management contract on Chain A to unlock the pledged funds of user A.

[0118] 5) Chain A's asset management contract will return the corresponding funds to the user who initially initiated the call, based on the cross-chain gateway's call.

[0119] The above process ensures the atomicity of cross-chain transactions and guarantees the security of users' funds.

[0120] Step 5: This step introduces the delivery process for multimodal digital assets. Based on the different confidentiality requirements and different data volume types of multimodal digital assets described in Step 2, this patent designs different delivery processes to ensure the security and reliability of the delivery process.

[0121] First, we will introduce the delivery process for multimodal digital assets without confidentiality requirements. The specific process is as follows: Figure 10As shown. Since this type of multimodal digital asset has no confidentiality requirements, and according to the asset structure design in step two, its complete data is stored directly in plaintext. Therefore, for the delivery of this type of multimodal digital asset, the delivery contract directly transfers the corresponding purchase funds to the seller of the corresponding asset, and then transfers ownership of the multimodal digital asset. If the buyer is on the current chain, the transfer is performed directly; if the buyer is a cross-chain user, the transfer is made to a temporary storage contract for holding. The process for cross-chain users to retrieve assets from the temporary storage contract will be described in subsequent steps.

[0122] The following describes the delivery process for multimodal data assets with high access frequency and privacy protection requirements. According to the design of this type of multimodal digital asset structure in step two, it stores ciphertext and digest of the complete encrypted data. However, this ciphertext is obtained by encrypting the original data using the current asset holder's public key. Since the buyer cannot obtain the current asset holder's private key, they cannot directly obtain the original plaintext. One feasible approach is for the current asset owner to encrypt the plaintext using the buyer's DID public key before uploading it to the blockchain. However, this method increases the risk of plaintext leakage and adds additional verification costs. To address these drawbacks, this patent, based on an "optimistic assumption" challenge period mechanism, designs a corresponding asset delivery scheme using "proxy re-encryption" technology, as detailed below. Figure 11 As shown, it includes the following steps:

[0123] 1) Once the delivery phase begins, the delivery contract sets a timer for the delivery instance. The asset seller must upload a re-encryption key generated based on the buyer's DID public key before the timer counts down. Otherwise, the transaction will be considered a failure, and the funds and multimodal digital assets will be returned.

[0124] 2) Once the asset seller uploads the re-encryption key generated based on the buyer's DID public key, the delivery contract enters a challenge period. If a user submits proof of the illegality of the re-encryption key during the challenge period, the transaction is considered a failure, and the funds and multimodal digital assets will be returned.

[0125] 3) After the challenge period ends, the delivery contract transforms the encrypted ciphertext stored in the multimodal digital asset based on the re-encryption key submitted by the asset seller, obtaining the ciphertext encrypted using the buyer's DID public key. The delivery contract then destroys the original multimodal digital asset and creates a new multimodal digital asset based on the new ciphertext and the original digest.

[0126] 4) The delivery contract transfers the corresponding purchase funds to the seller of the corresponding asset and transfers ownership of the multimodal digital asset. If the buyer is on the current chain, the transfer is performed directly; if the buyer is a cross-chain user, the transfer is made to a temporary storage contract for holding. The process for cross-chain users to withdraw assets from the temporary storage contract will be described in subsequent steps.

[0127] Finally, the delivery process for data assets with privacy protection requirements and low access frequency will be introduced. The data of the two types of multimodal digital assets mentioned above is essentially stored on-chain, so the entire transaction and delivery process exists on-chain. However, for data assets with privacy protection requirements and large data volumes, according to the design in step two, their digital asset structure contains a summary generated based on the original complete data, while the data itself is stored off-chain. For this scenario, this patent designs a method by introducing a "non-interactive zero-knowledge proof" technology based on "Zk-Sanrk". Figure 12 The delivery process shown includes the following steps:

[0128] 1) Because the original data of this type of digital asset is stored off-chain, the asset seller needs to deliver the original data off-chain with the asset buyer.

[0129] 2) After receiving the raw data from the asset seller, the asset buyer calculates a summary of the received data. If the summary matches the summary recorded in the corresponding digital asset, a confirmation of successful asset delivery is submitted. If the buyer is on the same blockchain, they can skip directly to step 5). If the buyer is on a cross-chain, they initiate a cross-chain confirmation request to the asset management contract on their blockchain, which will trigger a corresponding cross-chain event.

[0130] 3) Chain A's cross-chain gateway will continuously monitor relevant cross-chain events, including cross-chain events triggered by the asset management contract.

[0131] 4) When the cross-chain gateway of chain A detects a cross-chain event triggered by the asset management contract, it will generate and forward the corresponding cross-chain request to the cross-chain gateway of the target chain. The format of this request is: <did,TChainName,Address,ID,Proof did Proof c >, where ID represents the unique number of this transaction in the delivery contract, Proof did This is proof of the legitimacy and validity of the user's identity on chain A. c It is a zero-knowledge proof for user A of Chain A that has received data delivered off-chain. Zero-knowledge proof can prove that user A of Chain A has received the data without leaking the original data.

[0132] 5) After receiving a cross-chain request from the cross-chain gateway of chain A, the cross-chain gateway of chain B will verify the Proof in the request. did and Proof c The validity and legality of the delivery contract are verified. Once verified, the cross-chain gateway will initiate confirmation to the delivery contract; similarly, buyers on this chain will also initiate confirmation to the delivery contract after acceptance.

[0133] 6) The delivery contract transfers the corresponding purchase funds to the seller of the corresponding asset and transfers ownership of the multimodal digital asset. If the buyer is on the current chain, the transfer is performed directly; if the buyer is a cross-chain user, the transfer is made to a temporary storage contract for holding. The process for cross-chain users to withdraw assets from the temporary storage contract will be described in subsequent steps.

[0134] Step Six: This step mainly introduces how cross-chain asset buyers can extract purchased assets from the target chain to their own chain. In this patent design, the cross-chain asset purchase process involves setting up a "temporary storage contract"—a "proxy holder" contract—on the target chain. The essence of cross-chain asset extraction is transferring assets from the temporary storage contract to the blockchain where the asset buyer resides. The process designed for this step in this patent is as follows: Figure 13 As shown, it includes the following steps:

[0135] 1) Cross-chain users initiate asset withdrawal calls to the asset management contract of this chain. The format of the call is <did, TChainName, AID>, where AID is the unique identifier of the target asset to be withdrawn by the user.

[0136] 2) After the asset management contract receives the request, it will trigger a corresponding cross-chain event, which will be listened to and captured by the cross-chain gateway of chain A.

[0137] 3) After Chain A's cross-chain gateway detects a relevant cross-chain event, it generates an identity certificate and forwards the corresponding cross-chain request to the target chain's cross-chain gateway. The format of this request is <did, TChainName, AID, Proof>. did >, where Proof did It serves as proof of the legitimacy and validity of the identity of the user in Chain A.

[0138] 4) After receiving a cross-chain request from chain A, the cross-chain gateway of chain B will check the Proof in the request. did The verification process will proceed. Once the verification is successful, a call to the temporary contract will be initiated.

[0139] 5) Upon receiving a request to withdraw assets, the temporary storage contract will first verify whether the holder of the assets to be withdrawn matches the DID identity of the user initiating the withdrawal request. If they match, the asset will be locked, and the corresponding cross-chain event will be triggered.

[0140] 6) Chain B's cross-chain gateway listens to the above cross-chain event.

[0141] 7) Chain B's cross-chain gateway generates proof of the transaction that triggered the above cross-chain event and forwards the corresponding cross-chain request to Chain A's cross-chain gateway.

[0142] 8) After receiving a cross-chain request from Chain B, the cross-chain gateway of Chain A will first verify the validity and legality of the locked transaction proof. If the verification is successful, the corresponding assets will be minted into the asset management contract.

[0143] 9) The asset management contract transfers the corresponding assets to the user, realizing the change of ownership of multimodal digital assets and triggering the corresponding cross-chain events.

[0144] 10) Chain A's cross-chain gateway listens to the above cross-chain event.

[0145] 11) The cross-chain gateway of chain A generates proof of the asset transfer transaction and forwards the corresponding cross-chain request to the cross-chain gateway of chain B.

[0146] 12) After receiving a cross-chain request from Chain A, the cross-chain gateway of Chain B will first verify the validity and legality of the asset transfer transaction proof. After the verification is successful, it will initiate a destruction request to the temporary contract.

[0147] 13) After receiving a destruction request from the cross-chain gateway, the temporary storage contract will verify the validity of the proof and release the corresponding original assets from the locked state and destroy them.

[0148] The above process enables cross-chain extraction and transfer of multimodal digital assets.

[0149] Key aspects of this invention include:

[0150] 1. This invention provides a user DID registration, design, and verification scheme for multimodal digital asset transactions and delivery processes within a blockchain ecosystem comprised of multiple blockchains. Each blockchain operates independently but uses the same format and specifications. Within the same blockchain, users can authenticate each other. In cross-chain scenarios, proofs generated through cross-chain gateways enable mutual authentication between users on different blockchains within the same ecosystem, accelerating the processing speed of cross-chain asset transactions.

[0151] 2. This invention provides an event-driven, relay-free cross-chain message transmission protocol for cross-chain multimodal digital sub-asset trading and delivery scenarios based on a cross-chain gateway. This protocol does not require the introduction of a trusted third party, simplifies the message complexity in the cross-chain multimodal digital sub-asset trading and delivery process, and avoids the risks of centralization.

[0152] 3. This invention provides multiple selectable digital asset structure designs for digital assets with different modalities and privacy protection requirements, and offers various digital asset data compression schemes based on deep learning algorithms for different modalities of digital asset data. Furthermore, this invention presents a digital asset data storage method that combines on-chain and off-chain storage.

[0153] 4. This invention designs digital asset trading solutions for four scenarios, including auctions and order placements, targeting the two common forms of digital assets. It also introduces the concept of "nominee holders" to reduce the number of interactions between cross-chain users and improve the processing speed and security of cross-chain asset transactions.

[0154] 5. This invention designs a trusted delivery scheme for multimodal digital assets that supports both local and cross-chain user scenarios, addressing different privacy protection needs. It ensures the security of the assets of both parties during the transaction process, avoids the possibility of privacy data leakage during delivery by introducing various privacy protection technologies, including zero-knowledge proofs, and reduces the complexity of verification messages during delivery.

[0155] 6. Overall, this invention is aimed at the multimodal digital asset trading and circulation scenario in the Web3.0 context, and proposes a framework for digital asset trading and trusted delivery based on distributed identity and relay-free cross-chain.

[0156] Another embodiment of the present invention provides a multimodal digital asset transaction and trusted delivery system based on distributed identity and relay-free cross-chain, comprising:

[0157] The user registration module is used to register users on a blockchain in the blockchain ecosystem to obtain the corresponding DID identity, and to record the user DID in the DID management contract of the corresponding blockchain;

[0158] The digital asset minting module is used to design different token file structures for digital assets with different modalities, different privacy protection types, and data access frequencies. It also achieves hierarchical data storage for multimodal digital assets by combining on-chain and off-chain storage. Users send the data required for the corresponding type of token file structure to the digital asset management contract to complete the minting of digital assets.

[0159] The digital asset trading module is used by users to trade digital assets. It includes two different types of smart contracts: auction contracts and order contracts, as well as two ways for users to participate: cross-chain users and users of the same chain.

[0160] The digital asset delivery module is used to deliver multimodal digital assets according to different confidentiality requirements and access frequencies, ensuring the security and trustworthiness of the delivery process.

[0161] For the specific implementation process of each module, please refer to the description of the method of the present invention above.

[0162] Another embodiment of the present invention provides a computer device (computer, server, smartphone, etc.) including a memory and a processor, the memory storing a computer program configured to be executed by the processor, the computer program including instructions for performing the steps of the method of the present invention.

[0163] Another embodiment of the present invention provides a computer-readable storage medium (such as ROM / RAM, disk, optical disk) storing a computer program that, when executed by a computer, implements the various steps of the method of the present invention.

[0164] This invention is mainly compared with the following three technical solutions:

[0165] CN114077744A Blockchain-based general asset processing method, apparatus, equipment, and storage medium;

[0166] CN115865531A A method for authorizing re-encrypted digital assets through a proxy;

[0167] CN114997867A A multimodal delivery system and method for data elements based on blockchain and privacy computing.

[0168] For a detailed description of the above solutions, please refer to the background technology section. Compared with the method of this patent, the above solutions focus on the sharing and exchange of digital assets containing privacy data or the data itself on a single blockchain. They do not involve the transaction process of digital assets or the transaction and delivery process of other forms of digital assets for multimodal data. In addition, the above solutions are aimed at a single blockchain scenario and cannot be applied to the cross-chain scenario targeted by this patent.

[0169] The specific embodiments of the present invention disclosed above are intended to help understand the content of the present invention and to implement it accordingly. Those skilled in the art will understand that various substitutions, changes, and modifications are possible without departing from the spirit and scope of the present invention. The present invention should not be limited to the content disclosed in the embodiments of this specification; the scope of protection of the present invention is defined by the claims.

Claims

1. A method for multimodal digital asset transactions and trusted delivery based on distributed identity and relay-free cross-chain, characterized in that, Includes the following steps: Users register on a blockchain within the blockchain ecosystem to obtain a corresponding DID identity, and the user's DID is recorded in the DID management contract of the corresponding blockchain; Different token file structures are designed for digital assets with different modalities, different privacy protection types, and data access frequencies. Multi-modal digital asset data is stored in a hierarchical manner by combining on-chain and off-chain storage. Users send the data required for the corresponding type of token file structure to the digital asset management contract to complete the minting of digital assets. Users can trade digital assets through two different types of smart contracts: auction contracts and order contracts, as well as through cross-chain user participation and local chain user participation. Deliver multimodal digital assets according to different confidentiality requirements and access frequencies to ensure the security and trustworthiness of the delivery process.

2. The method according to claim 1, characterized in that, The format of the user DID is as follows: did:chainName:userName:authLevel Where chainName represents the unique identifier of the blockchain to which the new user is about to join in the blockchain ecosystem; userName represents the unique identifier of the new user; authLevel represents the permission level of the new user; the identifier of user DID is generated, allocated and recorded by the DID management contract on the target blockchain to which the user wants to join based on the registration request submitted by the user containing the user's public key.

3. The method according to claim 1, characterized in that, The multimodal digital assets include text, images, audio, and video; the token file structure supports digital assets of different modal types, and uses different file compression methods to compress the asset data size for different modal digital assets.

4. The method according to claim 1, characterized in that, The digital asset transactions adopt an event-driven, relay-free cross-chain processing scheme based on a cross-chain gateway, which achieves cross-chain transaction processing while ensuring transaction atomicity, and does not require the introduction of a trusted third party. Suppose a user on chain A wants to participate in an auction contract or a order placement contract on chain B. The event-driven, relay-free cross-chain processing solution based on a cross-chain gateway includes the following steps: 1) Initiate a call to the asset management contract deployed on Chain A, wherein the parameters of the call are:<did,TChainName,Address,ID,value> Where did represents the user's distributed identity, TChainName represents the unique identifier of the target chain of the cross-chain request initiated by the user in the current blockchain ecosystem, ID represents the number of the multimodal digital asset that the user wants to bid or buy in the auction contract or order contract, and value represents the bid or purchase price proposed by the user. 2) The asset management contract locks the corresponding assets based on the value in the call and triggers the corresponding cross-chain event; 3) After the cross-chain gateway of Chain A listens to the corresponding cross-chain event, it verifies whether the locking transaction that triggered the event was successfully executed; If the execution is successful, a proof is generated for the corresponding event and the cross-chain request is forwarded to the corresponding target chain; 4) After receiving a cross-chain request from the cross-chain gateway of chain A, the cross-chain gateway of chain B first verifies the identity proof and locking proof attached to the cross-chain request. After the verification is successful, it initiates the corresponding minting transaction and call request to the temporary contract. 5) After receiving the call, the temporary contract initiates a call to the corresponding target contract according to the call parameters. In this process, the temporary contract is regarded as the agent of the cross-chain user on chain B. 6) After a cross-chain user initiates a purchase or bid and succeeds, the digital assets and funds are first transferred to the delivery contract for further processing, following the same processing logic as a successful bid by a user on this chain. Secondly, when the delivery contract discovers that the delivery recipient is a cross-chain user, it will trigger the corresponding cross-chain event. 7) Chain B's cross-chain gateway continuously monitors cross-chain events on Chain B; 8) When the cross-chain gateway on Chain B detects a cross-chain event triggered by the delivery contract, it generates proof of the successful bidding or purchase transaction of the cross-chain user on Chain B, generates a cross-chain request, and forwards it to the cross-chain gateway of the corresponding chain; the format of the cross-chain request is: <did,TChainName,Address,ID,value,Proof tx >, where Proof tx Proof of successful transaction execution; 9) After receiving a cross-chain request from chain B, the cross-chain gateway of chain A first verifies the Proof. tx After verifying the legality and correctness of the asset management contract, the cross-chain gateway of Chain A initiates a call to the asset management contract on Chain A to permanently lock up the pledged funds of users on Chain A.

5. The method according to claim 4, characterized in that, When a cross-chain asset transaction request fails, the following steps should be followed: 1) If a pending contract transaction fails, the funds will be returned to the temporary contract when the transaction fails; If a successful bid in an auction contract is replaced by a higher price, the auction contract will invoke a temporary contract to return the funds to the temporary contract. 2) When a fund return event occurs during the temporary contract call, if the source of funds is a cross-chain user, the temporary contract will destroy the corresponding funds, i.e., transfer them to the black hole account, and trigger the corresponding cross-chain event. 3) After Chain B's cross-chain gateway detects a cross-chain event triggered by a refund in the temporary contract, it performs a transaction destruction to generate proof for the temporary contract and generates a corresponding cross-chain request, the format of which is: <did,TChainName,Address,ID,value,Proof burn >, where Proof burn It serves as proof that the funds corresponding to the temporary storage contract have been destroyed; 4) When the cross-chain gateway of chain A receives the relevant cross-chain request, it first verifies the Proof. burn After verifying the legality and correctness of the asset management contract, the cross-chain gateway of Chain A initiates a call to the asset management contract on Chain A to unlock the pledged funds of users on Chain A. 5) Chain A's asset management contract will return the corresponding funds to the user who initially initiated the call, based on the call from the cross-chain gateway.

6. The method according to claim 1, characterized in that, The delivery of multimodal digital assets based on different confidentiality requirements and access frequencies includes: For the delivery of multimodal digital assets without confidentiality requirements, the delivery contract directly transfers the corresponding purchase funds to the seller of the corresponding asset, and then transfers ownership of the multimodal digital asset; if the buyer is on the current chain, the transfer is carried out directly; if the buyer is a cross-chain user, the transfer is transferred to a temporary storage contract for holding. For the delivery of multimodal data assets with privacy protection requirements and high access frequency, the steps include: 1) After entering the delivery phase, the delivery contract sets a timer for the delivery instance. The asset seller uploads a re-encryption key generated based on the buyer's DID public key before the timer countdown; otherwise, the transaction is considered a failure, and the funds and multimodal digital assets are returned; 2) After the asset seller uploads the re-encryption key generated based on the buyer's DID public key, the delivery contract enters a challenge period. If a user submits proof of the illegality of the re-encryption key during the challenge period, the transaction is considered a failure, and the funds and multimodal digital assets are returned. 3) After the challenge period ends, the delivery contract transforms the encrypted ciphertext stored in the multimodal digital asset based on the re-encryption key submitted by the asset seller, obtaining the ciphertext encrypted using the buyer's DID public key. Then, the delivery contract destroys the original multimodal digital asset and creates a new multimodal digital asset based on the new ciphertext and the original digest; 4) The delivery contract transfers the corresponding purchase funds to the seller of the corresponding asset and transfers ownership of the multimodal digital asset. If the buyer is located on the current chain, the transfer is performed directly; if the buyer is a cross-chain user, the transfer is made to a temporary storage contract for holding. For the delivery of multimodal data assets with privacy protection requirements and low access frequency, the steps include: 1) The asset seller needs to deliver the original data off-chain with the asset buyer; 2) After receiving the original data from the asset seller, the asset buyer calculates the summary of the received data. If it matches the summary recorded in the digital asset corresponding to the data, the buyer submits a confirmation of successful asset delivery. If the buyer is on the same chain, the process jumps directly to step 5). If the buyer is on a cross-chain, the buyer initiates a cross-chain confirmation request to the asset management contract of the chain, and the asset management contract triggers the corresponding cross-chain event; 3) The cross-chain gateway of chain A continuously listens for the corresponding cross-chain events, including those triggered by the asset management contract; 4) When the cross-chain gateway of chain A detects a cross-chain event triggered by the asset management contract, it generates and forwards the corresponding cross-chain request to the cross-chain gateway of the target chain. The format of this request is: <did,TChainName,Address,ID,Proof did Proof c > where ID represents the unique number of this transaction in the delivery contract, Proof did It is a proof of the legitimacy and validity of the user's identity on Chain A. c This involves providing a zero-knowledge proof for the user of Chain A regarding the data already received via off-chain delivery; 5) After receiving a cross-chain request from the cross-chain gateway of Chain A, the cross-chain gateway of Chain B verifies the Proof in the request. did and Proof c The validity and legality of the transaction are verified. After the verification is passed, the cross-chain gateway initiates confirmation to the delivery contract. The buyer in this chain also initiates confirmation to the delivery contract after acceptance. 6) The delivery contract transfers the corresponding purchase funds to the seller of the corresponding asset and transfers the ownership of the multimodal digital asset. If the buyer is located in the current chain, the transfer is carried out directly. If the buyer is a cross-chain user, the transfer is transferred to the temporary storage contract for holding.

7. The method according to claim 6, characterized in that, The following steps are used to achieve cross-chain extraction and transfer of multimodal digital assets: 1) Cross-chain users initiate asset withdrawal calls to the asset management contract of this chain. The format of this call is as follows:<did,TChainName,AID> AID is a unique identifier for the target asset that the user wants to extract; 2) After the asset management contract receives the request, it will trigger a corresponding cross-chain event, which will be listened to and captured by the cross-chain gateway of chain A; 3) After Chain A's cross-chain gateway detects the relevant cross-chain event, it generates identity verification and forwards the corresponding cross-chain request to the target chain's cross-chain gateway. The format of this request is as follows: <did,TChainName,AID,Proof did >, where Proof did It serves as proof of the legitimacy and validity of the identity of the user in Chain A; 4) After receiving a cross-chain request from chain A, the cross-chain gateway of chain B checks the Proof in the request. did Perform verification, and once verification is successful, initiate a call to the temporary contract; 5) After receiving a request to withdraw assets, the temporary storage contract first verifies whether the holder of the assets to be withdrawn is consistent with the DID identity of the user who initiated the withdrawal request. If they are consistent, the asset is locked and the corresponding cross-chain event is triggered. 6) Chain B's cross-chain gateway listens to the cross-chain event described in step 5); 7) Chain B's cross-chain gateway generates proof of the locked transaction that triggered the cross-chain event and forwards the corresponding cross-chain request to Chain A's cross-chain gateway. 8) After receiving a cross-chain request from chain B, the cross-chain gateway of chain A first verifies the validity and legality of the locked transaction proof. If the verification is successful, the corresponding assets are minted into the asset management contract. 9) The asset management contract transfers the corresponding assets to the user, realizing the change of ownership of multimodal digital assets and triggering the corresponding cross-chain events; 10) Chain A's cross-chain gateway listens to the cross-chain event described in step 9); 11) The cross-chain gateway of chain A generates proof of the asset transfer transaction and forwards the corresponding cross-chain request to the cross-chain gateway of chain B. 12) After receiving a cross-chain request from chain A, the cross-chain gateway of chain B first verifies the validity and legality of the asset transfer transaction proof. After the verification is successful, it initiates a destruction request to the temporary contract. 13) After receiving a destruction request from the cross-chain gateway, the temporary storage contract will release the corresponding original assets from the locked state and destroy them after verifying the validity of the proof.

8. A multimodal digital asset transaction and trusted delivery system based on distributed identity and relay-free cross-chain, characterized in that, include: The user registration module is used to register users on a blockchain in the blockchain ecosystem to obtain the corresponding DID identity, and to record the user DID in the DID management contract of the corresponding blockchain; The digital asset minting module is used to design different token file structures for digital assets with different modalities, different privacy protection types, and data access frequencies. It also achieves hierarchical data storage for multimodal digital assets by combining on-chain and off-chain storage. Users send the data required for the corresponding type of token file structure to the digital asset management contract to complete the minting of digital assets. The digital asset trading module is used by users to trade digital assets. It includes two different types of smart contracts: auction contracts and order contracts, as well as two ways for users to participate: cross-chain users and users of the same chain. The digital asset delivery module is used to deliver multimodal digital assets according to different confidentiality requirements and access frequencies, ensuring the security and trustworthiness of the delivery process.

9. A computer device, characterized in that, It includes a memory and a processor, the memory storing a computer program configured to be executed by the processor, the computer program including instructions for performing the method of any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by a computer, implements the method according to any one of claims 1 to 7.

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