Some Remarks on Cocks'Identity-Based Encryption Scheme

The theory of quadratic residues plays an important role in cryptography.In 2001,Cocks developed an identity-based encryption(IBE)scheme based on quadratic residues,resolving Shamir’s 17-year-old open problem.However,a notable drawback of Cocks’scheme is the significant expansion of the ciphertext,and some of its limitations have been addressed in subsequent research.Recently,Cotan and Teşeleanu highlighted that previous studies on Cocks’scheme relied on a trial-and-error method based on Jacobi symbols to generate the necessary parameters for the encryption process.They enhanced the encryption speed of Cocks’scheme by eliminating this trialand-error method.Based on security analysis,this study concludes that the security of Cotan-Teşeleanu’s proposal cannot be directly derived from the security of the original Cocks’scheme.Furthermore,by adopting the Cotan-Teşeleanu method and introducing an additional variable as a public element,this study develops a similar enhancement scheme that not only accelerates the encryption speed but also provides security equivalent to the original Cocks’scheme.

福尔摩斯侦探小说叙事手法述略

福尔摩斯侦探小说是侦探小说的典范,研究者对其做过多方面的研究。文章借助几位研究者的观点通过对福尔摩斯侦探小说具体作品的分析总结了其三大叙事特点。

Provably Secure Self-Certified Signature Schemes with Message Recovery

To solve the key escrow problem of the identity-based cryptosystem, Girault introduced the notion of a self-certified public key, which not only eliminates the need to authenticate a public key but also solves the key escrow problerrL This paper proposes a Self-Certified Signature （SCS） scheme with message recovery and two variants without using bilinear pairings： one is the authenticated encryption scheme in which only the designated re- ceiver can verify the signature, and the other is the authenticated encryption scheme with message linkage that deals with large messages. These three SCS schemes are provably secure in the random oracle model and are more efficient than previous schemes .

Public-key encryption and authentication of quantum information

Public-key cryptosystems for quantum messages are considered from two aspects:public-key encryption and public-key authentication.Firstly,we propose a general construction of quantum public-key encryption scheme,and then construct an informationtheoretic secure instance.Then,we propose a quantum public-key authentication scheme,which can protect the integrity of quantum messages.This scheme can both encrypt and authenticate quantum messages.It is information-theoretic secure with regard to encryption,and the success probability of tampering decreases exponentially with the security parameter with regard to authentication.Compared with classical public-key cryptosystems,one private-key in our schemes corresponds to an exponential number of public-keys,and every quantum public-key used by the sender is an unknown quantum state to the sender.

Robust EPR-pairs-based quantum secure communication with authentication resisting collective noise

This work presents two robust quantum secure communication schemes with authentication based on Einstein-Podolsky-Rosen(EPR) pairs, which can withstand collective noises. Two users previously share an identity string representing their identities. The identity string is encoded as decoherence-free states(termed logical qubits), respectively, over the two collective noisy channels, which are used as decoy photons. By using the decoy photons, both the authentication of two users and the detection of eavesdropping were implemented. The use of logical qubits not only guaranteed the high fidelity of exchanged secret message, but also prevented the eavesdroppers to eavesdrop beneath a mask of noise.

An Improved Ring Signature Scheme without Trusted Key Generation Center for Wireless Sensor Network

Security of wireless sensor network （WSN） is a considerable challenge, because of limitation in energy, communication bandwidth and storage. ID-based cryptosystem without checking and storing certificate is a suitable way used in WSN. But key escrow is an inherent disadvantage for traditional ID-based cryptosystem, i.e., the dishonest key generation center （KGC） can forge the signature of any node and on the other hand the node can deny the signature actually signed by him/herself. To solving this problem, we propose an ID-based ring signature scheme without trusted KGC. We also present the accurate secure proof to prove that our scheme is secure against existential forgery on adaptively chosen message and ID attacks assuming the complexity of computational Diffie-Hellman （CDH） problem. Compared with other ring signature schemes, we think proposed scheme is more efficient.