Quantum Key Agreement

Ivan B. Djordjević

Takenobu Seito, Junji Shikata

In this paper, we study key-agreement which realizes the protection against key-exposure problems in the information-theoretic security setting. And we newly define a model and security notions for information-theoretically secure key-insulated key-agreement (KI-KA for short). In addition, we show tight lower bounds of sizes of entities' secret-keys required for KI-KA. We also propose constructions of KI-KA which are provably secure and optimal. Furthermore, we provide some applications of KI-KA.

Ray LaPierre

Reihaneh Safavi–Naini, Peng‐Wei Wang

Key agreement (KA) is a fundamental cryptographic primitive. Assuming that Alice and Bob do not have any prior shared correlation, it has been proved that key agreement with security against a computationally unbounded adversary is impossible if communication is either over a fully public channel, or the channel is fully controlled by the adversary. In this paper we consider a setting where communication is over a partially corrupted channel, and there is no prior shared correlation. We formalize security and reliability of key agreement protocols in this setting, derive bounds on the rate of secret key agreement, and give constructions that achieve the respective bounds. Our results show that secret key agreement, and hence secret message transmission, is possible, as long as a small fraction of the transmitted symbols in each round remain untouched by the adversary. Our results can be extended to key agreement between nodes in a network, when the two nodes are connected by a set of disjoint paths, and in each round a subset of paths is eavesdropped and another subset (possibly with overlap) is tampered with. We relate our results to previous works, and discuss future directions.

XU Chun-xiang

A few of certificateless key agreement schemes have been proposed in recent years,all of them need pairing operations,what's more,most of them are vulnerable to the key compromise impersonation attack and resistance to leakage of ephemeral keys.The provably secure certificateless key agreement protocol was proposed by Lippold in 2009,but their protocol suffered from computation burden.In order to solve the above-mentioned problem,this paper proposed a new pairing-free certificateless two party key agreement scheme (CL-KA) and presened its security properties.The new scheme was secure as long as each party had at least one uncompromised secret.Thus,the new scheme was secure even if the key generation centre learned the ephemeral secrets of both parties.The new scheme achieves efficiency in computational cost when compared with Lippold's protocol.