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1734results about How to "Reduce computational overhead" patented technology

Absolute public key cryptographic system and method surviving private-key compromise with other advantages

The present invention presents a public key cryptographic system and method called Absolute Public Key Cryptography that survives private key compromise and offers two-way communication security. Communications are secured even when the private key is revealed. It provides security to the private-to-public side communications and also allows short keys to be used with mobile devices that have low processing power. The system uses keys with two or more components and encrypts a message into the same number of cipher versions. The cipher versions are delivered to the destination in source routing mode, or hop-by-hop routing mode with a small time gap. The recipient performs certain mathematical operations on all the cipher versions and obtains the original message. All the versions are necessary for obtaining the original message. Even a single version missing leads to produce a junk for an attacker. As an attacker at an intermediary IP router can not have all the cipher versions available, he can not obtain the original message even when he knows the private key. This is why the system is called Absolute Public Key Cryptography. The robustness against private key compromise is achieved by blinding the public key through adding a random number to each of its components before encryption. When the encryption process is complete, the random number is discarded and the cipher versions are delivered to the recipient. The effect of blinding is made void by the actual intended recipient, who has all the cipher versions available. Robustness is also achieved another way, that is, by choosing the encrypting key such that each of its components has a common factor with Euler Totient Function of the key modulus, and there is no common factor among all the components. This makes it harder for an attacker to decrypt a single cipher version of the message into the original message and thereby allows smaller keys to be used for mobile communications. Communication in both directions is secured by using two different key pairs, one for public-to-private-side and the other for private-to-public-side communications.
Owner:KIOBA PROCESSING LLC

Method for deleting repeated data by using double-fingerprint hash check

The invention provides a method for deleting repeated data by using double-fingerprint hash check. The method comprises the following steps of: dividing an object to be backed up into data blocks to be backed up with equal lengths; judging whether the weak fingerprint of one of the data blocks to be backed up is the same as the weak fingerprint of any data block in a server; if the weak fingerprint of one of the data blocks to be backed up is different from the weak fingerprint of any data block in the server, backing up the data block; if the weak fingerprint of one of the data blocks to be backed up is the same as the weak fingerprint of any data block in the server, judging whether the strong fingerprint of the data block is the same as the strong fingerprint of any data block in the server; if the strong fingerprint of the data block is different from the strong fingerprint of any data block in the server, backing up the data block; and performing the operation on all data blocks to be backed up. In the method for deleting the repeated data, a hash function with low calculation amount is adopted at the first time to perform weak check on every data block and a has function with high calculation amount is adopted then to perform strong check, so the problem that all the data are checked by the hash function with the high calculation amount is avoided, the fingerprint calculation amount during checking is reduced greatly, the series performance is enhanced, and the appreciable transmission performance is provided for data backup based on mass data storage.
Owner:HUAZHONG UNIV OF SCI & TECH

Revocable key external package decryption method based on content attributes

The invention relates to a revocable key external package decryption method based on content attributes. For a trusted authority, 1, initialization is carried out, and system parameters are output; 2, a random number generation algorithm operates; 3, a collision-resistant Hash function is selected, and the Hash value is calculated; 4, a public key and a main key are calculated; 5, the random number is selected, and exponentiation calculation and multiplication are carried out; 6, the collision-resistant Hash function operates, the exponentiation operation is carried out, and a decryption key is obtained. For a data holder, 7, AES data encryption is carried out; 8, an access control matrix is generated; 9, a random number is selected, and an inner product is calculated; 10, multiplication, exponentiation and exclusive-or operation is operated, and ciphertexts are obtained. For a decryption operator, 11, a decryption request and a transformation key are sent. For a mobile storage serve provider, 12, CT2 is sent to an external package decryption agency. For the external package decryption agency, 13, the transformation key is utilized, and the transformation ciphertext is calculated. For the decryption operator, 14, a conversation key is obtained through calculation; 15, AES data decryption is carried out.
Owner:HANGZHOU INNOVATION RES INST OF BEIJING UNIV OF AERONAUTICS & ASTRONAUTICS

Efficient cryptograph image retrieval method capable of supporting privacy protection under cloud environment

The invention belongs to the technical field of image retrieval and discloses an efficient cryptograph image retrieval method capable of supporting privacy protection under a cloud environment. The efficient cryptograph image retrieval method capable of supporting the privacy protection under the cloud environment comprises the steps that an image owner firstly extracts characteristic vectors of an image in a database and encrypts the image by an AES or RSA encryption manner; the owner establishes indexes using a hierarchical K-means algorithm based on the characteristic vectors and uses a safe mode Hash technology to encrypt the indexes; and the encrypted image and indexes are uploaded to a cloud server, and a retrieval operation is executed. According to the invention, the privacy protection of the cryptograph image retrieval can be achieved, and retrieval accuracy equivalent with public image retrieval can be reached. In addition, detailed safety analysis of the disclosed method is conducted, and experimental assessment of efficiency and accuracy is conducted in different datasets. Results indicate that the method disclosed by the invention can reach expected safety targets, and can increase retrieval efficiency on the premise of ensuring retrieval accuracy.
Owner:XIDIAN UNIV

Cancellation-supported outsourcing verifiable multi-authorization center access control method, and cloud server

The invention belongs to the technical field characterized by a protocol, and discloses a cancellation-supported outsourcing verifiable multi-authorization center access control method, and a cloud server. The method comprises the following steps: system initialization, including the initialization of a global authentication center and other authorization centers; allocating an attribute set for auser by the authorization centers, and generating a secret key needed by decryption for the user; encrypting a file by a data owner, wherein the encryption process comprises outsourcing encryption, the verification of an outsourcing result and the final encryption of the data owner; issuing a file access request to a cloud service provider by the user, wherein the process includes cloud service provider outsourcing decryption, the verification of the outsourcing result, and the final decryption of the user; and cancelling some users or some attributes in a system. The cancellation-supported outsourcing verifiable multi-authorization center access control method provided by the invention has the advantages of being high in system access efficiency, low in computation overhead, capable of supporting dynamic user authority management and the like, and can be used for guaranteeing the privacy data safety of the user in cloud storage, reducing the computation overhead of the user and dynamically managing the authority of the user in the system.
Owner:XIDIAN UNIV

Efficient verifiable multi-keyword sequencing searchable encryption method supporting preference search and logic search

The invention discloses an efficient verifiable multi-keyword sequencing searchable encryption method supporting a preference search and a logic search. The encryption method comprises the following steps that a data owner encrypts a document, constructs a cryptogram index based on a document collection, generates summary information of the document by utilizing a secret key and the content of thedocument, and then sends a cryptogram document, an encrypted index and the summary information to a cloud server; a data user shares the information of the secret key, which is generated by the dataowner, generates a query trap door according to a query, and sends an encrypted query trap door and the number K of to-be-obtained documents to the cloud server; the cloud server can execute safe inner product operation after receiving the cryptogram index and the query trap door, searches for K documents most relevant to the query of the user, sequences according to relevant values among the K documents and the query, then generates verification objects, and finally returns the most relevant K documents and the verification objects to the data user, and the data user verifies the correctnessand completeness of a return result through a verification algorithm.
Owner:SOUTH CHINA UNIV OF TECH

Three-dimensional reconstruction method and system capable of maintaining sharp features

The present invention discloses a three-dimensional reconstruction method and system capable of maintaining sharp features. The method includes the following steps that: 1) a two-dimensional image filtering method extended to a three-dimensional space is adopted to perform smoothing de-noising on inputted roughly-registered point cloud; 2) an improved region growth method is adopted to perform outlier removal on the smoothed roughly-registered point cloud; 3) a kd-tree (k-dimensional tree) acceleration-based ICP (iterative closest point) algorithm is adopted to perform precise registration on the outlier-removed roughly-registered point cloud; 4) a neighborhood search and boundary point detection-based fusion method is adopted to fuse the precisely-registered point cloud; and 5) a feature point detection and adaptive step size update-based method is adopted to perform surface reconstruction on the fused precisely-registered point cloud. The three-dimensional reconstruction system is composed of a point cloud preprocessing module, a point cloud combining module and a surface reconstruction module. The three-dimensional reconstruction system which is realized based on the method of the invention can maintain the sharp features of the edge of a reconstructed model, and therefore, reconstruction speed is considered with accuracy ensured.
Owner:SOUTH CHINA UNIV OF TECH
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