Parallel sparse interpolation using small primes

To interpolate a supersparse polynomial with integer coefficients, two alternative approaches are the Prony-based "big prime" technique, which acts over a single large finite field, or the more recently-proposed "small primes" technique, which reduces the unknown sparse polynomial to many low-degree dense polynomials. While the latter technique has not yet reached the same theoretical efficiency as Prony-based methods, it has an obvious potential for parallelization. We present a heuristic "small primes" interpolation algorithm and report on a low-level C implementation using FLINT and MPI.Comment: Accepted to PASCO 201

Guardianship in Group Key Exchange for Limited Environments

Post-compromise security (PCS) has been a core goal of end-to-end encrypted messaging applications for many years, both in one-to-one continuous key agreement (CKA) and for groups (CGKA). At its essence, PCS relies on a compromised party to perform a key update in order to `self-heal\u27. However, due to bandwidth constraints, receive-only mode, and various other environmental demands of the growing number of use cases for such CGKA protocols, a group member may not be able to issue such updates. In this work, we address the issue of devices functioning in limited mode through the introduction of guardianship, where a designated guardian can perform key updates on the behalf of its paired edge device. We introduce a Guardianship PCS (GPCS) security, and provide an associated security experiment. We investigate various architectural designs in the pursuit of GPCS, provide constructions and security analyses, and describe trade-offs

Aminophenyl/Carboxyphenylporphyrins as Sensitizers for Dye-Sensitized Solar Cells

A series of tetraphenyl meso-substituted porphyrins with either p-amino or p-carboxy substituents has been studied as dyes for standard dye-sensitized solar cells (DSSCs). The porphyrins with greater numbers of amino groups generally show greater efficiency, primarily due to higher photocurrents; open-circuit voltage and fill factors are comparable. The most efficient sensitizer was the trans disubstituted zinc porphyrin, with an overall solar energy conversion efficiency of 5.66%, slightly higher than the triamino zinc porphyrin at 5.18%. The improved efficiency is attributed to the well known push–pull effect in porphyrinsensitized DSSCs with electrondonating groups opposite to the electronwithdrawing anchoring (carboxy) groups. It is suggested that porphyrin derivatives with cis diaminophenyl groups show somewhat diminished efficiency due to difficulties with regeneration of the dye from its oxidized form. Read More: http://www.worldscientific.com/doi/abs/10.1142/S108842461650056

Aminophenyl/carboxyphenylporphyrins as Sensitizers for Dye-sensitized Solar Cells

A series of tetraphenyl meso-substituted porphyrins with either p-amino or p-carboxy substituents has been studied as dyes for standard dye-sensitized solar cells (DSSCs). The porphyrins with greater numbers of amino groups generally show greater efficiency, primarily due to higher photocurrents; open-circuit voltage and fill factors are comparable. The most efficient sensitizer was the trans disubstituted zinc porphyrin, with an overall solar energy conversion efficiency of 5.66%, slightly higher than the triamino zinc porphyrin at 5.18%. The improved efficiency is attributed to the well known push–pull effect in porphyrinsensitized DSSCs with electrondonating groups opposite to the electronwithdrawing anchoring (carboxy) groups. It is suggested that porphyrin derivatives with cis diaminophenyl groups show somewhat diminished efficiency due to difficulties with regeneration of the dye from its oxidized form