A New Family of Pairing-Friendly elliptic curves

International audienceThere have been recent advances in solving the finite extension field discrete logarithm problem as it arises in the context of pairing-friendly elliptic curves. This has lead to the abandonment of approaches based on supersingular curves of small characteristic, and to the reconsideration of the field sizes required for implementation based on non-supersingular curves of large characteristic. This has resulted in a revision of recommendations for suitable curves, particularly at a higher level of security. Indeed for a security level of 256 bits, the BLS48 curves have been suggested, and demonstrated to be superior to other candidates. These curves have an embedding degree of 48. The well known taxonomy of Freeman, Scott and Teske only considered curves with embedding degrees up to 50. Given some uncertainty around the constants that apply to the best discrete logarithm algorithm, it would seem to be prudent to push a little beyond 50. In this note we announce the discovery of a new family of pairing friendly elliptic curves which includes a new construction for a curve with an embedding degree of 54

Negative parabolic magneto-resistance induced by electron-electron interaction in two-dimensional electron gas with diffusive transport

We experimentally study the parabolic negative magneto-resistance (NMR) in high density (N-s > 10(12) cm(-2)) and low mobility (mu < 10(3) cm(2)/V s) two-dimensional (2D) electron gas realized by delta-doping a narrow (5 nm) AlGaAs/GaAs/AlGaAs quantum well. We show that the parabolic NMR in this 2DEG is well described by the theory which connects the parabolic NMR to the existing quantum logarithmic correction to the conductivity of the 2D electron system in the case of the diffusive transport. (C) 2003 Elsevier B.V. All rights reserved

Gated wires and interferometers based on Si/SiGe heterostructures

We report the fabrication and study of gated quantum wires and interferometers based on a Si/SiGe heterostructure fabricated by electron lithography and anisotropic ion etching. In the wires, negative magnetoresistance connected with weak localisation effects and in the ring, Aharonov-Bohm oscillations were investigated in the temperature range 30 mK-5 K. The phase coherence time was found to be due to electron- electron scattering with small energy transfer and magnetic impurity scattering. High magnetic field Aharonov-Bohm oscillations connected with the interference of edge states current have been observed in Si/SiGe ring for the first time. (C) 2002 Elsevier Science B.V. All rights reserved

Decentralized Attribute-Based Signatures

Abstract. In this paper, we present the first decentralized multi-authority attribute-based signature (DMA-ABS) scheme, in which no central authority and no trusted setup are required. The proposed DMA-ABS scheme for general (non-monotone) predicates is fully secure (adaptive-predicate unforgeable and perfect private) under a standard assumption, the decisional linear (DLIN) assumption, in the random oracle model. Our DMA-ABS scheme is comparably as efficient as the most efficient ABS scheme. As a by-product, this paper also presents an adaptively secure DMA functional encryption (DMA-FE) scheme under the DLIN assumption