Lower Bounds for Lattice-based Compact Functional Encryption

Functional encryption (FE) is a primitive where the holder of a master secret key can control which functions a user can evaluate on encrypted data. It is a powerful primitive that even implies indistinguishability obfuscation (iO), given sufficiently compact ciphertexts (Ananth-Jain, CRYPTO\u2715 and Bitansky-Vaikuntanathan, FOCS\u2715). However, despite being extensively studied, there are FE schemes, such as function-hiding inner-product FE (Bishop-Jain-Kowalczyk, AC\u2715, Abdalla-Catalano-Fiore-Gay-Ursu, CRYPTO’18) and compact quadratic FE (Baltico-Catalano-Fiore-Gay, Lin, CRYPTO’17), that can be only realized using pairings. This raises whether there are some mathematical barriers which hinder us from realizing these FE schemes from other assumptions. In this paper, we study the difficulty of constructing lattice-based compact FE. We generalize the impossibility results of Ünal (EC\u2720) for lattice-based function-hiding FE, and extend it to the case of compact FE. Concretely, we prove lower bounds for lattice-based compact FE schemes which meet some (natural) algebraic restrictions at encryption and decryption, and have messages and ciphertexts of constant dimensions. We see our results as important indications of why it is hard to construct lattice-based FE schemes for new functionalities, and which mathematical barriers have to be overcome

Inhibited spontenaous emission of perylene dye molecules embedded in nano-cavities

Abstract:{|}The radiative properties of molecules placed in cavities differ fundamentally from the radiative properties in free space. Fluorescence lifetime measurements of perylene dye molecules in polymer nanocavities are experimentally studied using time-correlated single photon counting techniques. The fluorescence lifetime of perylene is measured to be 4.8 ns. Perylene is embedded into polyacrylonitrile nanofibers and polymethylmethacrylate films. Spontaneous emission rate of perylene is inhibited by a factor of up to 2.6. Thus, the enhancement of fluorescence lifetime of perylene from 4.8 ns to 12.36 us for polyacrylonitrile nanofibers and to 12.3 ns for polymethylmethacrylate films is observed

The diagnostic values of ischemia-modified albumin in patients with acute abdominal pain and its role in differentiating acute abdomen

Aim. The aim of this study was to evaluate the diagnostic value of serum ischemia-modified albumin (IMA) levels in patients presenting to the emergency department with acute abdominal pain and its use in differentiating acute surgical abdomen. Methods. This single-center prospective cross-sectional study included 334 adult patients who presented to the emergency department. These consisted of 194 patients (Group 1) with nontraumatic abdominal pain commencing in the preceding week, who were definitely diagnosed and either hospitalized in a specific department or planned for discharge, and a control group of 140 patients (Group 2). Results. The mean IMA value of the patients diagnosed with acute appendicitis was statistically significantly higher than that of the control group. The mean IMA value of the patients diagnosed with acute appendicitis, ovarian pathologies, and gastritis-peptic ulcer was statistically significantly higher than that of the nonspecific abdominal pain group. Conclusion. Serum IMA levels can be used as a diagnostic marker in patients with acute appendicitis. Furthermore, serum IMA levels in patients presenting to the emergency department with abdominal pain may be indicative of patients requiring surgery or of complicated cases, particularly in terms of acute appendicitis and ovarian pathologies