4 results about "Chosen-ciphertext attack" patented technology

The invention provides a collaborative decryption method and device, a data encryption method and device, equipment, a medium and a product, and relates to the technical field of information security, the method adopts a collaborative mechanism of an MLWE problem to ensure the security of quantum computing attack resistance, and at the same time, through fragmented key management of a client and a server, the security of quantum computing attack resistance is ensured. Residence of the complete private key at a single node is avoided, and the risk of single-point leakage is eliminated; in the collaborative decryption process, the client only sends a ciphertext component and abstract information to trigger collaboration, so that the communication bandwidth overhead is reduced, and the attack of selecting the ciphertext is effectively defended by utilizing an abstract binding mechanism; besides, the server side can only complete partial decryption calculation based on the private key fragment and cannot see the original plaintext, so that the confidentiality of user data and the reliability of system operation are guaranteed while the collaborative function is realized.

The invention relates to the technical field of block chains and cryptography, in particular to a decentralized group communication authentication broadcast encryption method based on a block chain. Through six core steps of system initialization, user initialization, CRS generation, network joining, signature / encryption and verification / decryption, public parameters and a global CRS vector are generated through an intelligent contract, a user can complete key negotiation and identity verification without multiple rounds of interaction, and the communication process is concise and efficient; the sender generates a ciphertext with a fixed size and broadcasts the ciphertext to the block chain, and the receiver independently completes key reconstruction and decryption by virtue of a private key of the receiver, so as to eliminate dependence on a central mechanism and a single-point fault risk; on the basis of a bilinear group cryptography hypothesis, under a random oracle model, the random oracle model has selected ciphertext attack security and strong unforgeability under selected message attack; key negotiation and broadcast encryption can be completed by one round of communication without a central mechanism, and security, high efficiency and expansibility are considered.

The invention provides a self-adaptive security proxy re-encryption method and system with compact security, and belongs to the technical field of cryptography. The method supports operation under honest re-encryption attack and selective ciphertext attack security models, and comprises the following steps: executing system initialization based on security parameters, and outputting public parameters; executing a key generation algorithm based on the public parameter, outputting a public key and a private key of the user, and generating a re-encryption token based on the private key; executing an encryption algorithm based on the user public key and the plaintext message, and outputting a ciphertext; executing a decryption algorithm based on the user private key and the ciphertext, and recovering the plaintext message; and executing a re-encryption algorithm based on the re-encryption token, the source user public key, the target user public key and the ciphertext, and outputting a re-encrypted ciphertext. According to the invention, the problem that the security loss is increased along with the user number index under the self-adaptive attack in the existing scheme is solved. And the internal contradiction between the CCA security and the re-encryption function is solved.

This application provides a security protection method and apparatus, relating to the field of cryptography. The input polynomial provided in this application is obtained by operating on input data and an input mask. This makes it difficult for attackers to recover the original input data or private key even if they can monitor certain details of the decryption process, thereby enhancing protection against side-channel attacks and improving security. Furthermore, this application determines the target threshold based on the input polynomial and target offset, effectively narrowing the range of input data and increasing the difficulty of launching chosen-ciphertext attacks, thus also improving security. Moreover, this application only outputs the decryption result with an additional XOR mask when the values ​​of the first and second flag bits are different. This not only avoids security vulnerabilities caused by illegal input or abnormal situations but also ensures that even if an attacker can observe the final decryption result, they cannot directly deduce the true message bit value, further improving security.