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

Quality of Fe3O4 Films Prepared by Plasma Assisted MOCVD

Fe3O4 films have been grown on Si substrates by plasma-assisted MOCVD using acetylacetonate iron complex as a gas source. Relationship between the deposition rate of the film and substrate temperature indicated a possibility that part of the source molecules may be decomposed into iron-oxide molecule and an intermediate by plasma applied in a diffusion process to the substrate surface. These reaction species allowed growth of Fe3O4 films with low carbon contamination and good surface morphology at low temperature of 400°C

Electrical properties of MgO insulating layers in spin-dependent tunneling junctions using Fe3O4

We investigated the growth conditions and electrical properties of MgO epitaxial thin films, which have potential applications as insulating layers for spin-dependent tunneling devices where Fe3O4 serves as one of the magnetic electrodes. Our investigation showed that epitaxial MgO films with high crystalline quality can be successfully grown at temperatures as low as 473 K in oxygen pressures less than 1×10-5Torr. This is a very important result because it indicates that the oxidation of the underlying Fe3O4 electrode is not a factor in fabrication of spin-dependent tunneling devices. We also examined the electron tunneling properties of Au/MgO/Fe3O4 junction with an ultrathin MgO layer prepared under the conditions described above and found excellent electron tunneling properties, as will be discussed. Barrier height and thickness estimated by curve fitting current density-voltage curves using the Simmons equation yielded barrier height and thicknesses of 0.9 eV and 2.5 nm, respectively. These values were consistent with those estimated by taking into account the reduction of the barrier height due to image forces. These results indicate that the MgO insulating layers grown under the restricted conditions have satisfactory electrical qualities required for spin tunneling devices