An efficient MAC protocol with adaptive energy harvesting for machine-to-machine networks

In a machine-to-machine network, the throughput performance plays a very important role. Recently, an attractive energy harvesting technology has shown great potential to the improvement of the network throughput, as it can provide consistent energy for wireless devices to transmit data. Motivated by that, an efficient energy harvesting-based medium access control (MAC) protocol is designed in this paper. In this protocol, different devices first harvest energy adaptively and then contend the transmission opportunities with energy level related priorities. Then, a new model is proposed to obtain the optimal throughput of the network, together with the corresponding hybrid differential evolution algorithm, where the involved variables are energy-harvesting time, contending time, and contending probability. Analytical and simulation results show that the network based on the proposed MAC protocol has greater throughput than that of the traditional methods. In addition, as expected, our scheme has less transmission delay, further enhancing its superiority

Tightly Secure Chameleon Hash Functions in the Multi-User Setting and Their Applications

We define the security notion of (strong) collision resistance for chameleon hash functions in the multi-user setting ((S-)MU-CR security). We also present three constructions, CHF_dl, CHF_rsa and CHF_fac, and prove their tight S-MU-CR security based on the discrete logarithm, RSA and factoring assumptions, respectively. In applications, our tightly S-MU-CR secure chameleon hash functions help us to lift a signature scheme from (weak) unforgeability to strong unforgeability in the multi-user setting, and the security reduction is tightness preserving. Furthermore, they can also be used to construct tightly secure online/offline signatures, chameleon signatures and proxy signatures, etc., in the multi-user setting

KDM-Secure Public-Key Encryption from Constant-Noise LPN

The Learning Parity with Noise (LPN) problem has found many applications in cryptography due to its conjectured post-quantum hardness and simple algebraic structure. Over the years, constructions of different public-key primitives were proposed from LPN, but most of them are based on the LPN assumption with _low noise_ rate rather than _constant noise_ rate. A recent breakthrough was made by Yu and Zhang (Crypto\u2716), who constructed the first Public-Key Encryption (PKE) from constant-noise LPN. However, the problem of designing a PKE with _Key-Dependent Message_ (KDM) security from constant-noise LPN is still open. In this paper, we present the first PKE with KDM-security assuming certain sub-exponential hardness of constant-noise LPN, where the number of users is predefined. The technical tool is two types of _multi-fold LPN on squared-log entropy_, one having _independent secrets_ and the other _independent sample subspaces_. We establish the hardness of the multi-fold LPN variants on constant-noise LPN. Two squared-logarithmic entropy sources for multi-fold LPN are carefully chosen, so that our PKE is able to achieve correctness and KDM-security simultaneously