Abstract: A method comprises: selecting one or more blockchain assets from a remitter's blockchain account according to a transaction amount of a transaction to be remitted from the remitter's blockchain account into a receiver's blockchain account, wherein a total asset amount represented by the selected one or more blockchain assets is not less than the transaction amount, and a commitment of an individual asset amount represented by each of the selected one or more blockchain assets is recorded in a blockchain; generating a commitment of the transaction amount; and submitting to the blockchain the transaction comprising information of the selected one or more blockchain assets and the commitment of the transaction amount, for the selected one or more blockchain assets to be removed from the remitter's blockchain account and one or more blockchain assets corresponding to the commitment of the transaction amount to be added to the receiver's blockchain account.

Abstract: A computer-implemented method comprises: committing a transaction amount t of a transaction with a commitment scheme to obtain a transaction commitment value T, the commitment scheme comprising at least a transaction blinding factor r_t; encrypting a combination of the transaction blinding factor r_t and the transaction amount t with a public key PK_B of a recipient of the transaction; and transmitting the transaction commitment value T and the encrypted combination to a recipient node associated with the recipient for the recipient node to verify the transaction.

Abstract: A computer-implemented method comprises: committing a transaction amount of a transaction with a commitment scheme to obtain a transaction commitment value, the commitment scheme comprising at least a transaction blinding factor; generating a first key of a symmetric key pair; encrypting a combination of the transaction blinding factor and the transaction amount t with the first key; and transmitting the transaction commitment value T and the encrypted combination to a recipient node associated with a recipient of the transaction for the recipient node to verify the transaction. The first key is a symmetrical key generated with Diffie-Hellman (DH) key exchange protocol that can be used to encrypt/decrypt the random numbers and the plaintext balances, thus providing convenient management. The method provides a robust privacy protection for transaction amounts, asset values, and blinding factors in commitment schemes.

Abstract: A computer-implemented blockchain-based transaction obfuscation method includes: determining a submission time based on a base time and a submission time interval; determining that no actual transaction information is obtained between the base time and the submission time during the submission time interval; generating false transaction information; cryptographically encoding transaction content in the false transaction information; and subsequent to the submission time, submitting the false transaction information to a blockchain to obfuscate a number of actual transactions in the blockchain.

Abstract: Implementations of this specification include receiving a synchronization request from a light-weight node of the blockchain network including an identity of the light-weight node; identifying one or more permissions associated with the identity of the light-weight node; determining an original world state structure associated with the block height and including a plurality of account records; identifying based on the one or more permissions, a subset of the plurality of account records that are authorized for access by the light-weight node; generating an isolated world state structure based on the original world state data structure including only the subset of the plurality of account records that are authorized for access by the light-weight node; sending a response to the light-weight node that includes the isolated world state data structure.

Abstract: This disclosure relates to anonymous transactions based on ring signatures. In one aspect, a method includes receiving a remittance transaction. The remittance transaction is generated by a client device of a remitter by assembling unspent assets in an account corresponding to the remitter and masked assets in an account corresponding to a masked participant. Key images are obtained from a linkable spontaneous anonymous group (LSAG) signature of the remittance transaction. Values of the key-images are based on a private key, a public key, and unspent assets of the remitter. The LSAG signature is verified. The LSAG signature is generated by the client device of the remitter based on the private key and the public key of the remitter, and a second public key of the masked participant. The remittance transaction is executed when a transaction execution condition is met.

Abstract: A method for implementing blockchain-based transactions includes: determining a to-be-remitted amount for each of a plurality of remitters participating in a transaction and a to-be-received amount for each of a plurality of receivers participating in the transaction, wherein the plurality of remitters include one or more real remitters, the plurality of receivers include one or more real receivers, and the plurality of remitters include one or more cover-up remitters and/or the plurality of receivers include one or more cover-up receivers; generating a commitment of the to-be-remitted amount corresponding to the each remitter and a commitment of the to-be-received amount corresponding to the each receiver; and submitting the transaction to a blockchain for execution, wherein the transaction comprises blockchain account addresses of the remitters and receivers, and the commitments of the to-be-remitted amounts and the to-be-received amounts.

Abstract: Embodiments of the application provide a method, apparatus, and electronic device for implementing blockchain-based transactions. The method comprises: determining a transaction amount to be remitted from a remitter's blockchain account into a receiver's blockchain account, wherein a commitment of the remitter's balance is recorded with the remitter's blockchain account in a blockchain, a commitment of the receiver's balance is recorded with the receiver's blockchain account in the blockchain; obtaining a commitment of the transaction amount by using the homomorphic encryption algorithm according to the transaction amount; and submitting to the blockchain a transaction comprising information of the remitter's and the receiver's blockchain accounts, and the commitment of the transaction amount, for the commitment of the transaction amount to be deducted from the commitment of the remitter's balance and the commitment of the transaction amount to be added to the commitment of the receiver's balance.

Abstract: The present disclosure relates to an image processing method and apparatus, an electronic device, and a storage medium. The method includes: obtaining video streams of a game tabletop; detecting target objects in a plurality of image frames included in the video streams; determining a current game stage based on the target objects; and determining game detecting results according to the target objects and the determined game stage.

Abstract: The present invention discloses a nanocomposite membrane for heavy metal rejection and a preparation method thereof. The nanocomposite membrane comprises a porous membrane prepared from a two-dimensional sheet material and a hydrophilic inorganic nanomaterial distributed between the sheets of the two-dimensional material. The effective pore size of the nanocomposite membrane under wet conditions is not greater than 1.2 nm. The static water contact angle of the nanocomposite membrane is not greater than 45°. The preparation method of the nanocomposite membrane comprises: adding reactants on both sides of a nanoporous membrane to carry out an interfacial synthesis reaction to obtain the nanocomposite membrane. The method is simple and controllable. Driven by lower pressure, heavy metal ions in water are rejected by a pore size screening function, thereby achieving the purpose of deep removal. The nanocomposite membrane can be used to quickly remove heavy metal ions from water.

Abstract: A method includes: determining, by a computing device communicably coupled to a blockchain network, participants in a remittance transaction, in which each participant has a corresponding account in a blockchain ledger of the blockchain network, and in which each account includes one or more assets; assembling the remittance transaction based on one or more to-be-spent assets of the one or more assets in an account corresponding to a real remitter, one or more covered assets of the one or more assets in an account corresponding to a fake remitter, and one or more encrypted transfer amounts; generating a linkable ring signature for the remittance transaction based on a private key held by the real remitter, a public key held by the real remitter, and a public key held by the fake remitter; and submitting the remittance transaction and the linkable ring signature to the blockchain network for completion.

Abstract: A computer-implemented method includes: determining assets held by a remitter, the assets to be spent in a remittance transaction between the remitter and one or more payees, in which each asset corresponds to a respective asset identifier, a respective asset amount, and a respective asset commitment value; determining a remitter pseudo public key and a remitter pseudo private key; determining a cover party pseudo public key, in which the cover party pseudo public key is obtained based on asset commitment values of assets held by the cover party; and generating a linkable ring signature for the remittance transaction.

Abstract: Implementations of this specification include receiving a synchronization request from a light-weight node of the blockchain network including an identity of the light-weight node; identifying one or more permissions associated with the identity of the light-weight node; determining an original world state structure associated with the block height and including a plurality of account records; identifying based on the one or more permissions, a subset of the plurality of account records that are authorized for access by the light-weight node; generating an isolated world state structure based on the original world state data structure including only the subset of the plurality of account records that are authorized for access by the light-weight node; sending a response to the light-weight node that includes the isolated world state data structure.

Abstract: A node device in a blockchain receives an asset issuance transaction from an asset issuer, where the asset issuance transaction comprises a commitment value and a proof for performing a zero-knowledge proof with respect to the commitment value, and where the commitment value is calculated by inputting at least an asset type of a target asset object issued by the asset issuer to a commitment function. The zero-knowledge proof with respect to the commitment value based on the proof is initiated. It is determined that the asset type of the target asset object is in a set of legal asset types allowed to be issued by the asset issuer. In response to determining that the asset type of the target asset object is in the set of legal asset types allowed to be issued by the asset issuer, the commitment value to the blockchain is issued for storage.

Abstract: A computer-implemented method for information protection comprises: committing a transaction amount of a transaction with a first commitment scheme to obtain a transaction commitment value, committing a change of the transaction with a second commitment scheme to obtain a change commitment value, the first commitment scheme comprising a transaction blinding factor, and the second commitment scheme comprising a change blinding factor; encrypting a first combination of the change blinding factor and the change with a first key; transmitting the transaction blinding factor, the transaction amount, and the transaction commitment value to a recipient node associated with a recipient for the recipient node to verify the transaction; in response to that the recipient successfully verifies the transaction, obtaining an encrypted second combination of the transaction blinding factor and the transaction amount encrypted with a second key.

Abstract: Disclosed herein are methods, systems, and apparatus, including computer programs encoded on computer storage media, for managing user authorizations for blockchain-based services. One of the methods includes: at a service platform, receiving, from a computing device associated with a user, an encryption key and data for storage on a blockchain, wherein the data includes public data and private data, and the encryption key encrypts the private data; storing the encryption key and an identifier (ID) of the data in a cache storage dedicated to storing smart contract data for executing a smart contract; and invoking an application programming interface (API) to enable a blockchain node to initiate a consensus algorithm to record the data and the ID of the data on a blockchain.

Abstract: Implementations of this specification include receiving a synchronization request from a light-weight node of the blockchain network including an identity of the light-weight node; identifying one or more permissions associated with the identity of the light-weight node; determining an original world state structure associated with the block height and including a plurality of account records; identifying based on the one or more permissions, a subset of the plurality of account records that are authorized for access by the light-weight node; generating an isolated world state structure based on the original world state data structure including only the subset of the plurality of account records that are authorized for access by the light-weight node; sending a response to the light-weight node that includes the isolated world state data structure.

Abstract: A computer-implemented method includes: determining assets held by a remitter, the assets to be spent in a remittance transaction between the remitter and one or more payees, in which each asset corresponds to a respective asset identifier, a respective asset amount, and a respective asset commitment value; determining a remitter pseudo public key and a remitter pseudo private key; determining a cover party pseudo public key, in which the cover party pseudo public key is obtained based on asset commitment values of assets held by the cover party; and generating a linkable ring signature for the remittance transaction.

Abstract: A method for implementing blockchain-based transactions comprises: determining a transaction amount to be remitted from a remitter's blockchain account into a receiver's blockchain account, wherein a balance of the remitter's blockchain account comprises multiple reserve balances, and commitments of the reserve balances are recorded in a blockchain; selecting one or more of the reserve balances from the remitter's blockchain account, wherein the sum of the selected one or more reserve balances is not smaller than the transaction amount; and submitting to the blockchain a transaction comprising an identification of each of the selected one or more reserve balances and a commitment of the transaction amount, for the selected one or more reserve balances to be removed from the remitter's blockchain account and the transaction amount to be added to the receiver's blockchain account.

Abstract: One or more embodiments of the present specification provide blockchain-based remittance methods and apparatuses. One method comprising: receiving, from an account of a remitter, a transaction for a remittance to an account of a remittee, wherein the transaction comprises a remittance amount of the remittance and at least one reserved amount corresponding to the remittance amount allocated by the remitter from a reserve fund list to the transaction; performing verification of the transaction, wherein the verification comprises determining whether a total amount of the at least one reserved amount comprised in the transaction is greater than or equal to the remittance amount; and in response to determining that the verification is successful: deducting the remittance amount from the balance of the account of the remitter, and adding the remittance amount to a balance of the account of the remittee.