Abstract: A method for blockchain-based time stamping for digital signature is disclosed. The method includes two participants: a signer who signs a message, a verifier who verifies the message. In the method, the signer obtains hash values of a certain number of latest confirmed blocks in blockchain, binds these hash values and the message together to be a new message. The signer then generates a signature of the new message and inserts identification data of this signature and the new message into a transaction of blockchain. This method ensures that the generation time of the signature is prior to the generation time of the block which contains the signature and, at the same time, is after the generation time of the blocks whose hash values are included in the signature, which produces an accurate time interval for the digital signature.

Abstract: The present invention discloses a bidirectional ultraviolet light emitting diode (UV LED) based on N—ZnO/N—GaN/N—ZnO heterojunction as well as its preparation method. The LED includes: N—ZnO microwires, a N—GaN film, a PMMA protective layer and alloy electrodes; and its preparation method includes the following steps: lay two N—ZnO microwires on the N—GaN film, then spin-coat a PMMA protective layer on the film to fix the N—ZnO microwires until the PMMA protective layer spreads over the N—ZnO microwires, and then place the film on a drying table to solidify the PMMA protective layer; then etch the PMMA protective layer with O2 to expose the N—ZnO microwires, and prepare alloy electrodes on different N—ZnO microwires to construct a N—ZnO/N—GaN/N—ZnO heterojunction to constitute a complete device. The present invention constructs an N/N/N symmetrical structure; the device is composed of N—ZnO and N—GaN, emits light in the ultraviolet region and has a small turn-on voltage.

Abstract: A blockchain-based public parameter generation method against backdoor attacks, includes: acquiring the hash values of L latest confirmed blocks on a blockchain, and the hash values of the L blocks and a count variable for generation are mapped to an element in a set G via a specified mapping to obtain the generated public parameter; L??, ? is the minimum number to guarantee blockchains' chain quality property; checking whether the generated parameter meets the condition, if not, discarding the parameter and updating the generated public parameter; if the condition is met, outputting the public parameter to the device that uses the public parameter. In this disclosure, the public parameters are random, since they are based on the latest confirmed blocks on the blockchain and are guaranteed by the computational power of the blockchain; the generation of public parameters is publicly verifiable and random.

Abstract: The present invention discloses a bidirectional ultraviolet light emitting diode (UV LED) based on N—ZnO/N—GaN/N—ZnO heterojunction as well as its preparation method. The LED includes: N—ZnO microwires, a N—GaN film, a PMMA protective layer and alloy electrodes; and its preparation method includes the following steps: lay two N—ZnO microwires on the N—GaN film, then spin-coat a PMMA protective layer on the film to fix the N—ZnO microwires until the PMMA protective layer spreads over the N—ZnO microwires, and then place the film on a drying table to solidify the PMMA protective layer; then etch the PMMA protective layer with O2 to expose the N—ZnO microwires, and prepare alloy electrodes on different N—ZnO microwires to construct a N—ZnO/N—GaN/N—ZnO heterojunction to constitute a complete device. The present invention constructs an N/N/N symmetrical structure; the device is composed of N—ZnO and N—GaN, emits light in the ultraviolet region and has a small turn-on voltage.

Abstract: A method for blockchain-based time stamping for digital signature is disclosed. The method includes two participants: a signer who signs a message, a verifier who verifies the message. In the method, the signer obtains hash values of a certain number of latest confirmed blocks in blockchain, binds these hash values and the message together to be a new message. The signer then generates a signature of the new message and inserts identification data of this signature and the new message into a transaction of blockchain. This method ensures that the generation time of the signature is prior to the generation time of the block which contains the signature and, at the same time, is after the generation time of the blocks whose hash values are included in the signature, which produces an accurate time interval for the digital signature.

Abstract: A method for generating a group key are provided in the field of network communications. The method includes the following steps: Group members select DH secret values and generate DH public values. An organizer generates an intermediate message and broadcasts a DH public value and the intermediate message. The group members generate a group key according to a DH secret value selected by the organizer and DH public values of the other group members except the organizer. A system for generating a group key and communication devices are also disclosed in the present invention.

Abstract: A method for generating a group key are provided in the field of network communications. The method includes the following steps: Group members select DH secret values and generate DH public values. An organizer generates an intermediate message and broadcasts a DH public value and the intermediate message. The group members generate a group key according to a DH secret value selected by the organizer and DH public values of the other group members except the organizer. A system for generating a group key and communication devices are also disclosed in the present invention.

Abstract: The present invention relates to a method for the preparation of compound of microarray chips, especially the method by repeatedly impressing reagents at fixed locations on a substrate to synthesize said chips; and also realtes to a compound microarray chips produced according to said method.