We present a security analysis against collective attacks for a time-energy entanglement-based quantum key distribution protocol, given the practical constraints of single photon detector efficiency, channel loss, and finite-key considerations. We find a positive secure-key capacity when the key length increases beyond 104 for eight-dimensional systems. The minimum key length required is reduce...

Group key transfer protocols allow multiple parties to share a common secret key. They rely on a mutually trusted key generation center (KGC) that selects the key and securely distributes it to the authorized participants. Recently, Sun et al. proposed an authenticated group key transfer protocol based on secret sharing that they claim to be secure. We show that this is false: the protocol is s...

Few days ago Grigoriev and Shpilrain have proposed to build a system for transmission of information without a shared secret, or essentially a sort of public key cryptosystem, based on properties of physical systems [2]. In this paper we show that their second scheme based on capacitors is insecure and extremely easy to break in practice.

This paper is concerned with key escrow protocols for use in international communications environments, where communication domains do not necessarily trust one another. It is concerned particularly with systems where users place their trust collectively with groups of trusted third parties. We consider two different protocols, discuss and improve their efficiency and generalise the type of key...

In a (t, n) secret sharing scheme (SS), a dealer divides the secret into n shares in such way that any t or more than t shares can reconstruct the secret but fewer than t shares cannot reconstruct the secret. The multi-SS is an extension of the (t, n) SS in which shares can be reused to reconstruct multiple secrets. Thus, the efficiency of the multi-SS is better than the efficiency of the (t, n...

Diffie and Hellman invented in 1976 a protocol bearing their names (Diffie-Hellman) that was at the origin of the cryptography. The most important characteristic of this protocol is that it enables two connected parties to generate a shared secret without having any preliminary information about one other. However, The point of vulnerability of this protocol is the active attack and more precis...