Abstract: A method and system for encryption and assured deletion of information is provided, the method at least includes: sorting fields of the information into at least two sensitivity levels by sensitivity; generating encryption keys and key shards thereof based on predetermined thresholds, and creating mapping between targets and the key shards, based on the encryption keys for the sensitivity levels, encrypting the information fields of the corresponding sensitivity levels and deleting the original information and encryption keys; and in response to reception of a recover request, recovering the encryption keys based on the key shards and performing decryption, so as to recover the original information. The present disclosure aims at the problem that information is difficult to be safely stored and assuredly deleted, and realizes multi-party security key deletion of encrypted personal information.

Abstract: A method and system for automatic deletion of information based on time synchronization and trusted counting is provided, the method including: defining different data structures including configurations in a normalized manner; setting triggering conditions for automatic information deletion, including conditions for automatic deletion based on time synchronization and/or based on trusted counting; maintaining synchrony of the configurations across different domains; and after satisfying the triggering conditions, making an information source domain and/or an information propagation domain perform the automatic information deletion.

Abstract: A method for increasing the difficulty for attackers to launch keyword guessing attacks, which uses a time-delay encryption with a keyword search based on a public key that generates searchable ciphertexts and/or files ciphertexts for keywords of at least one file that uploaded by time-delay encryption from a cloud server. A system for implementing the method is also described.

Abstract: The present invention relates a method for ensuring search completeness of searchable public key encryption, applicable to a blockchain network formed by a plurality of computer nodes. The method at least comprises: the blockchain network receiving a keyword ciphertext and a corresponding file-identifier ciphertext generated by a transmitting end based on the public key encryption, and at least one miner storing the ciphertexts in a ciphertext table; the blockchain network receiving a search trapdoor Tw transmitted by a receiving end, generated according to a private key and a keyword w to be searched; the at least one miner in the blockchain network performing a secure search based on information of a state table and the search trapdoor Tw, and outputting a search result to the blockchain network; and the blockchain network feeding the search result back to the receiving end.

Abstract: The present invention relates to a method and a system for robust, searchable, symmetrical encryption, the method comprising: during initialization, having a retrieval server perform retrieval on stored ciphertext information according to a searchable ciphertext and retrieval trapdoor information (Cntupd, K, Locgrp) sent by a client, wherein, the retrieval server acquires a last received first ciphertext set Cnew from a ciphertext database CDB just before the present retrieval according to a retrieval key K and an encryption counter Cntupd sent by the client, acquiring a second ciphertext set Ccache in a retrieval request history from a cache ciphertext database GRP according to a cache ciphertext index Locgrp, and merging the first ciphertext set Cnew and the second ciphertext set Ccache to form a retrieval set , and sending it to the client for decryption.

Abstract: The present invention relates a method for ensuring search completeness of searchable public key encryption, applicable to a blockchain network formed by a plurality of computer nodes. The method at least comprises: the blockchain network receiving a keyword ciphertext and a corresponding file-identifier ciphertext generated by a transmitting end based on the public key encryption, and at least one miner storing the ciphertexts in a ciphertext table; the blockchain network receiving a search trapdoor Tw transmitted by a receiving end, generated according to a private key and a keyword w to be searched; the at least one miner in the blockchain network performing a secure search based on information of a state table and the search trapdoor Tw, and outputting a search result to the blockchain network; and the blockchain network feeding the search result back to the receiving end.

Abstract: The present invention relates to a method of time-delay encryption with keyword search and system using the same, at least comprising: based on a public key PK, generating searchable ciphertexts Cw and/or file ciphertexts for keywords w of at least one to-be-uploaded file by means of time-delay encryption and uploading the ciphertexts to a cloud server; sending at least one keyword search trapdoor Tw generated for one said to-be-searched keyword w based on a private key SK to the cloud server; and the cloud server, based on the keyword search trapdoor Tw performing keyword search on all the searchable ciphertexts Cw so as to obtain the corresponding searchable ciphertexts Cw, and determining the corresponding file ciphertexts based on the searched searchable ciphertexts Cw and feeding the corresponding file ciphertexts to a receiving end. The present invention increases the difficulty for attackers to launch keyword guessing attacks.

Abstract: The present invention relates to a method and a system for robust, searchable, symmetrical encryption, the method comprising: during initialization, having a retrieval server perform retrieval on stored ciphertext information according to a searchable ciphertext and retrieval trapdoor information (Cntupd, K, Locgrp) sent by a client, wherein, the retrieval server acquires a last received first ciphertext set Cnew from a ciphertext database CDB just before the present retrieval according to a retrieval key K and an encryption counter Cntupd sent by the client, acquiring a second ciphertext set Ccache in a retrieval request history from a cache ciphertext database GRP according to a cache ciphertext index Locgrp, and merging the first ciphertext set Cnew and the second ciphertext set Ccache to form a retrieval set , and sending it to the client for decryption.