50 results about "Random oracle" patented technology

The invention provides a safety analysis method based on a SelfTargetSIS problem. The method comprises the following steps: modeling a solution target of the SelfTargetSIS problem into explicit search on a message set, an allowable vector set and a challenge vector set; estimating a first search complexity in the classic model under a random oracle model; estimating a second search complexity in the quantum model under a random oracle model; and determining the minimum value of the first search complexity and the known classical optimal attack complexity as the effective attack complexity under the classical model, and determining the minimum value of the second search complexity and the known quantum optimal attack complexity as the effective attack complexity under the quantum model, thereby performing security evaluation on the anti-quantum signature. According to the method, an explicit search path based on a message set, an allowable vector set and a challenge vector set is supplemented and quantified, and the attack cost in the real world can be reflected more comprehensively.

Homomorphic attribute-based encryption (HABE) is a useful cryptographic primitive that supports both fine-grained access control and computation over ciphertexts. However, existing HABE schemes are limited to the homomorphic evaluation of circuits with either bounded depth or a restricted number of inputs. To address this problem, the present disclosure introduce a bootstrappable, fully homomorphic attribute-based encryption (FHABE) scheme that supports computations of circuits with unbounded depth over cross-attribute ciphertexts. Compared to state-of-the-art schemes, the proposed scheme also has a more lightweight ciphertext and eliminates the reliance on the random oracle model. Additionally, the present disclosure extend the FHABE to a proxy re-encryption setting, proposing an attribute-based homomorphic proxy re-encryption scheme that facilitates efficient sharing of encrypted data. This scheme is the first lattice-based multi-hop attribute-based proxy re-encryption scheme with unbounded hops of re-encryptions.

The application discloses a kind of blockchain privacy query method and system based on inadvertent transmission technology, comprising: when user initiates blockchain data query, blockchain end and user end negotiate key by a kind of random oracle-based key exchange protocol, blockchain end uses key and returns data set ciphertext with obfuscated data to user, and user obtains data ciphertext and uses key only to decrypt the data required.This method can avoid the details of user query obtained by blockchain end, and at the same time, user cannot obtain plaintext data except target data, ensuring the privacy of blockchain data query.

The invention relates to a distributed digital signature suitable for a block chain environment, and discloses an identity-based threshold signature algorithm suitable for a block chain to support a password reverse firewall, which can prove that existence unforgeability security under adaptive selection message attack can be satisfied under a random oracle model. The method is characterized in that an identity-based threshold signature mechanism is adopted, so that the overhead of certificate generation, management and revocation in a traditional PKI system is avoided, and the method is suitable for a scene of direct binding of an identity and a key in a block chain. Besides, according to the algorithm, when the signature key and the random number are generated, a Shamir secret sharing technology is combined, so that an effective signature can be synthesized when the number of participating users reaches a preset threshold value, the system security is guaranteed, and fault tolerance and flexibility are enhanced. Meanwhile, a password reverse firewall (CRF) is introduced, privacy information is re-randomized in the signature process, information leakage attacks can be effectively resisted, even if secret keys of part of participants are leaked, the system can still keep overall safety and cannot be counterfeited for signature, and robustness and usability in a complex hostile environment are remarkably improved.

The invention discloses a distributed key generation method, device and equipment, belongs to the technical field of distributed key storage and key management, and aims to solve the problems of leakage and loss of a private key of a block chain and insufficient security of a traditional management scheme. The method comprises the following steps: generating a public and private key pair in a chain relation when a secret key is initialized, performing distributed storage on a private key, a public key and an associated random number in the form of a secret share, and disclosing a commitment value; during transaction, selecting a preset number of nodes, converting a private key share into an additive share, cooperatively finishing threshold signature, and ensuring that the private key is not recovered to be complete; if the private key is leaked, a previous generation of private key share update is generated after verification of the preorder node; and if the share is lost, selecting nodes for joint sharing recovery. According to the method, a third-party authority is not needed, safety can be proved in a Random Oracle mode, and safety and availability are effectively balanced.