Compact E-Cash and Simulatable VRFs Revisited

Abstract. Efficient non-interactive zero-knowledge proofs are a powerful tool for solving many cryptographic problems. We apply the recent Groth-Sahai (GS) proof system for pairing product equations (Eurocrypt 2008) to two related cryptographic problems: compact e-cash (Eurocrypt 2005) and simulatable verifiable random functions (CRYPTO 2007). We present the first efficient compact e-cash scheme that does not rely on a random oracle. To this end we construct efficient GS proofs for signature possession, pseudo randomness and set membership. The GS proofs for pseudorandom functions give rise to a much cleaner and substantially faster construction of simulatable verifiable random functions (sVRF) under a weaker number theoretic assumption. We obtain the first efficient fully simulatable sVRF with a polynomial sized output domain (in the security parameter).

Zero-Knowledge Arguments for Matrix-Vector Relations and Lattice-Based Group Encryption

International audienceGroup encryption (GE) is the natural encryption analogue of group signatures in that it allows verifiably encrypting messages for some anonymous member of a group while providing evidence that the receiver is a properly certified group member. Should the need arise, an opening authority is capable of identifying the receiver of any ciphertext. As introduced by Kiayias, Tsiounis and Yung (Asiacrypt'07), GE is motivated by applications in the context of oblivious retriever storage systems, anonymous third parties and hierarchical group signatures. This paper provides the first realization of group encryption under lattice assumptions. Our construction is proved secure in the standard model (assuming interaction in the proving phase) under the Learning-With-Errors (LWE) and Short-Integer-Solution (SIS) assumptions. As a crucial component of our system, we describe a new zero-knowledge argument system allowing to demonstrate that a given ciphertext is a valid encryption under some hidden but certified public key, which incurs to prove quadratic statements about LWE relations. Specifically, our protocol allows arguing knowledge of witnesses consisting of X ∈ Z m×n q , s ∈ Z n q and a small-norm e ∈ Z m which underlie a public vector b = X · s + e ∈ Z m q while simultaneously proving that the matrix X ∈ Z m×n q has been correctly certified. We believe our proof system to be useful in other applications involving zero-knowledge proofs in the lattice setting

Effect of an enriched drink on cognitive function in frail elderly persons

Many elderly persons report that they have difficulties learning new things and remembering names, plans, and conversations. Because decreased cognitive function in elderly persons is potentially related to their poor nutritional status, provision of essential nutrients may improve cognitive function. The authors wanted to determine whether consumption of an enriched drink, including moderate doses of all essential micronutrients, improves cognitive function in frail elderly persons. Methods. Frail, white adults (n = 101) who were aged 65 years or older with a body mass index ¿25 kg/m 2 were selected for this randomized, double-blind, placebo-controlled trial. They received either an enriched drink or a placebo product for 6 months. Before and after the intervention, participants' cognitive function was assessed (word learning test [WLT], WLT delayed, category fluency [CF] for animals and professions, and recognition memory test for words [RMTW]) and blood biochemical analyses (vitamin B12, homocysteine) were performed. Results. Sixty-seven residents completed the study period. After 6 months, significant differences were noted in changes of the WLT (0.9 ± 0.3 vs-0.1 ± 0.3; p = .014) and CF professions (1.2 ± 0.7 vs -0.6 ± 0.5; p = .017) in the supplement group (n = 34) compared with the placebo group (n = 33). No significant differences were observed in WLT delayed, RMTW, and CF animals. The plasma vitamin B12 concentration increased (105 ± 50 vs 8 ± 16; p = .003) and the homocysteine concentration decreased (-6.3 ± 5.9 vs -0.3 ± 2.9; p = .000) in the supplement group compared with the placebo group. Conclusions. This study contributes to the evidence that nutritional supplementation may improve neuropsychological performance in frail elderly persons

GABA TURNOVER in MOUSE-BRAIN - AGREEMENT BETWEEN the RATE of GABA ACCUMULATION AFTER AMINOOXYACETIC ACID and the RATE of DISAPPEARANCE AFTER 3-MERCAPTOPROPIONIC ACID

ESCOLA PAULISTA MED,DEPT FARMACOL,BR-01000 São Paulo,BRAZILESCOLA PAULISTA MED,DEPT FARMACOL,BR-01000 São Paulo,BRAZILWeb of Scienc

CIRCULATORY EFFECTS of DECEREBRATION in the UNANESTHETIZED SPONTANEOUSLY HYPERTENSIVE RAT

GOTENBURG UNIV,DEPT PHARMACOL,S-41124 GOTHENBURG,SWEDENWeb of Scienc

INTERACTION of ALPHA-ADRENERGIC and BETA-ADRENERGIC-RECEPTOR BLOCKING-AGENTS in the CONSCIOUS RAT

ESCOLA PAULISTA MED, DEPT FARMACOL, São Paulo 01000, SP, BRAZILESCOLA PAULISTA MED, DEPT FARMACOL, São Paulo 01000, SP, BRAZILWeb of Scienc

ROLE of GABA-ERGIC RECEPTORS for the SYNTHESIS of GABA in DIFFERENT COMPARTMENTS of the RAT CEREBELLUM

ESCOLA PAULISTA MED,DEPT FARMACOL,São Paulo 04023,SP,BRAZILESCOLA PAULISTA MED,DEPT FARMACOL,São Paulo 04023,SP,BRAZILWeb of Scienc

ON the IMPORTANCE of GABA-ERGIC NEURONS for the AOAA INDUCED ACCUMULATION of GABA in the RAT-BRAIN

ESCOLA PAULISTA MED,DEPT FARMACOL,CP 20372,São Paulo 01000,SP,BRAZILESCOLA PAULISTA MED,DEPT FARMACOL,CP 20372,São Paulo 01000,SP,BRAZILWeb of Scienc