104 research outputs found
Post-Quantum Single Secret Leader Election (SSLE) from Publicly Re-Randomizable Commitments
Full text linkA Single Secret Leader Election (SSLE) enables a group of parties to randomly choose exactly one leader from the group with the restriction that the identity of the leader will be known to the chosen leader and nobody else. At a later time, the elected leader should be able to publicly reveal her identity and prove that she is the elected leader. The election process itself should work properly even if many registered users are passive and do not send any messages. SSLE is used to strengthen the security of proof-of-stake consensus protocols by ensuring that the identity of the block proposer remains unknown until the proposer publishes a block. Boneh, Eskandarian, Hanzlik, and Greco (AFT'20) defined the concept of an SSLE and gave several constructions. Their most efficient construction is based on the difficulty of the Decision Diffie-Hellman problem in a cyclic group.
In this work we construct the first efficient SSLE protocols based on the standard Learning With Errors (LWE) problem on integer lattices, as well as the Ring-LWE problem. Both are believed to be post-quantum secure. Our constructions generalize the paradigm of Boneh et al. by introducing the concept of a re-randomizable commitment (RRC). We then construct several post-quantum RRC schemes from lattice assumptions and prove the security of the derived SSLE protocols. Constructing a lattice-based RRC scheme is non-trivial, and may be of independent interest
Perioperative dietary therapy in inflammatory bowel disease. Journal of Crohn and Colitis.
No full textAdamina M, Gerasimidis K, Sigall-Boneh R, Zmora O, de Buck van Overstraeten A, Campmans-Kuijpers M, Ellul P, Katsanos K, Kotze P, Noor N, Schäfli-Thurnherr J, Vavricka S, Wall C, Wierdsma N, Yassin N, Lomer M. (2019) jjz160
Revisiting the Uber Assumption in the Algebraic Group Model: Fine-Grained Bounds in Hidden-Order Groups and Improved Reductions in Bilinear Groups
Full text linkWe prove strong security guarantees for a wide array of computational and decisional problems, both in hidden-order groups and in bilinear groups, within the algebraic group model (AGM) of Fuchsbauer, Kiltz and Loss (CRYPTO '18). As our first contribution, we put forth a new fine-grained variant of the Uber family of assumptions in hidden-order groups. This family includes in particular the repeated squaring function of Rivest, Shamir and Wagner, which underlies their time-lock puzzle as well as the main known candidates for verifiable delay functions; and a computational variant of the generalized BBS problem, which underlies the timed commitments of Boneh and Naor (CRYPTO '00). We then provide two results within a variant of the AGM, which show that the hardness of solving problems in this family in a less-than-trivial number of steps is implied by well-studied assumptions. The first reduction may be applied in any group (and in particular, class groups), and is to the RSA assumption; and our second reduction is in RSA groups with a modulus which is the product of two safe primes, and is to the factoring assumption.
Additionally, we prove that the hardness of any computational problem in the Uber family of problems in bilinear groups is implied by the hardness of the q-discrete logarithm problem. The parameter q in our reduction is the maximal degree in which a variable appears in the polynomials which define the specific problem within the Uber family. This improves upon a recent result of Bauer, Fuchsbauer and Loss (CRYPTO '20), who obtained a similar implication but for a parameter q which is lower bounded by the maximal total degree of one of the above polynomials. We discuss the implications of this improvement to prominent group key-exchange protocols
Traceable Verifiable Random Functions
Full text linkA threshold verifiable random function (threshold VRF) is a VRF where the evaluation key is secret shared among parties, and a quorum of parties is needed to evaluate the VRF. Threshold VRFs are used widely in practice in applications such as randomness beacons and deterministic wallets. Despite their long history, the question of accountability for leaking key shares in a threshold VRF has not been studied. Specifically, consider a set of parties who use their key shares to create an evaluation box that lets anyone evaluate the VRF at any point in the domain of the VRF. When is less than the threshold , this box must also take as input additional evaluation shares. Our goal is to design a threshold VRF where there is a tracing algorithm that can trace any such box to the coalition of parties that created it, using only blackbox access to . The risk of tracing should deter the coalition from selling such a box. Questions in this vein were previously explored in the context of threshold decryption and secret sharing. Here we define and study traceability for a threshold VRF.
Our traceable threshold VRF is built from a VRF based on Paillier encryption. The starting point for our tracing algorithm is the tracing technique of Boneh-Partap-Rotem (Crypto 2024) designed for tracing leaks in the context of secret sharing. However, there are multiple technical challenges in making this approach work, and we develop the necessary tools to overcome all these challenges. The end result is a threshold VRF with a provably secure tracing algorithm
Evolving role of diet in the pathogenesis and treatment of inflammatory bowel diseases
No full textRecent advances in basic and clinical science over the last 3 years have dramatically altered our appreciation of the role of diet in inflammatory bowel diseases (IBD). The marked increase in incidence of these diseases along with the important role of non-genetic susceptibility among patients with IBD has highlighted that these diseases have a strong environmental component. Progress in the field of microbiome and IBD has demonstrated that microbiome appears to play an important role in pathogenesis, and that diet may in turn impact the composition and functionality of the microbiome. Uncontrolled clinical studies have demonstrated that various dietary therapies such as exclusive enteral nutrition and newly developed exclusion diets might be potent tools for induction of remission at disease onset, for patients failing biologic therapy, as a treatment for disease complications and in reducing the need for surgery. We review these advances from bench to bedside, along with the need for better clinical trials to support these interventions.</jats:p
Post-Quantum Single Secret Leader Election (SSLE) From Publicly Re-randomizable Commitments
Full text linkA Single Secret Leader Election (SSLE) enables a group of parties to randomly choose exactly one leader from the group with the restriction that the identity of the leader will be known to the chosen leader and nobody else. At a later time, the elected leader should be able to publicly reveal her identity and prove that she is the elected leader. The election process itself should work properly even if many registered users are passive and do not send any messages. SSLE is used to strengthen the security of proof-of-stake consensus protocols by ensuring that the identity of the block proposer remains unknown until the proposer publishes a block. Boneh, Eskandarian, Hanzlik, and Greco (AFT\u2720) defined the concept of an SSLE and gave several constructions. Their most efficient construction is based on the difficulty of the Decision Diffie-Hellman problem in a cyclic group.
In this work we construct the first efficient SSLE protocols based on the standard Learning With Errors (LWE) problem on integer lattices, as well as the Ring-LWE problem. Both are believed to be post-quantum secure. Our constructions generalize the paradigm of Boneh et al. by introducing the concept of a re-randomizable commitment (RRC). We then construct several post-quantum RRC schemes from lattice assumptions and prove the security of the derived SSLE protocols. Constructing a lattice-based RRC scheme is non-trivial, and may be of independent interest
Response to treatment is more important than disease severity at diagnosis for prediction of early relapse in new-onset paediatric Crohn’s disease
No full textBACKGROUND:
Paediatric Crohn's disease is characteried by frequently relapsing disease which may lead to hospitalisations and complications.
AIM:
To develop predictive models for early relapse following first remission.
METHODS:
The GROWTH CD prospective inception cohort was designed to predict risk for early disease relapse and poor outcomes. Newly diagnosed children underwent endoscopies and imaging. They were phenotyped and followed at scheduled visits through 78 weeks for relapses. Twenty-eight dichotomous and continuous variables were assessed at baseline and week 12, including phenotype, inflammatory markers, disease activity (PCDAI) and other markers. Clinical relapses defined as PCDAI >10 after remission were recorded using a relapse form. Logistic regression & risk modelling was performed.
RESULTS:
We enrolled 282 eligible patients of whom 178 (63.6%) patients achieved steroid free remission by week 12. Disease complications developed in 22/76(29%) of patients with relapse compared to 20/206 (9.7%) without relapse (P = 0.01). Multivariable analysis demonstrated that while variables from age/gender at diagnosis were not predictive, week 12 variables including PCDAI >5 (P = 0.02), CRP >20 mg/L (P = 0.02), and faecal calprotectin >400 μg/g (P = 0.03) as optimal cut-offs were associated with increased risk of relapse. A prediction model for patients in remission including gender, age, week 12 PCDAI, calprotectin and CRP had sensitivity 43%, specificity 92%, PPV 78%, NPV 71% for relapse.
CONCLUSIONS:
Early relapses were associated with a higher risk for disease complications at followup. Relapse prediction based on week 12 disease activity or inflammation is superior to prediction using data from diagnosis
Assessment of hemostatic profile in neonates with necrotizing enterocolitis using Rotational Thromboelastometry (ROTEM)
No full textBackground: This study aimed to explore the hemostatic profile of neonates with necrotizing enterocolitis (NEC) using Rotational Thromboelastometry (ROTEM) and to investigate if ROTEM parameters have the capacity to play a role in the differentiation of NEC from sepsis at the disease onset. Methods: This observational study included 62 neonates (mean gestational age 31.6 weeks and mean birth weight 1620g) hospitalized in a neonatal intensive care unit. The neonates were categorized in three groups: neonates with NEC (Bell stage II and above), neonates with sepsis and healthy neonates and they were matched 1:1:1 with regards to gestational age, delivery mode, and sex. Clinical, laboratory data as well as measurements of ROTEM parameters at disease onset were recorded. Results: ROTEM parameters differed between neonates with NEC and neonates with sepsis, indicating that NEC results in accelerated clot formation and higher clot strength compared to sepsis. The EXTEM CFT and A10 parameters demonstrated the highest diagnostic performance for NEC in terms of discrimination between NEC and sepsis (AUC, 0.997; 95% CI: 0.991–1.000 and 0.973; 95% CI: 0.932–1.000, respectively). Conclusions: Neonates with NEC manifested accelerated clot formation and higher clot strength compared to septic and healthy neonates, as these were expressed by ROTEM parameters. Impact: This work reports data on the hemostatic profile of neonates with necrotizing enterocolitis (NEC) using Rotational Thromboelastometry (ROTEM) and the capacity of ROTEM parameters in differentiating of NEC from sepsis at the disease onset. Neonates with NEC present acceleration of coagulation and exhibit a hypercoagulable profile, as this is expressed by ROTEM parameters, in comparison to septic and healthy neonates. ROTEM parameters demonstrated a good diagnostic capacity in differentiating NEC from sepsis at the disease onset. © The Author(s), under exclusive licence to the International Pediatric Research Foundation, Inc 2023
Differences in outcomes over time with exclusive enteral nutrition compared to steroids in children with mild to moderate Crohn's Disease: results from the GROWTH CD study
No full textExclusive enteral nutrition (EEN) and corticosteroids (CS) both induce similar rates of remission in mild to moderate pediatric Crohn's disease (CD), but differ with regard to mucosal healing. Our goal was to evaluate if EEN at diagnosis was superior to CS for improving long term outcomes
"Simha Rotem (1924-2018): Ad memoriam. The broom and the resilience"
No full textSimha Rotem was born in Warsaw in 1924. He was one of the most important member of the Warsaw
Ghetto uprising in April 1943. Under the cover name of Kazik. He was a leader of the young Jews who were one of the
first in Europe to rebel against the Nazi occupation. His original name is Symon Rathajzer, who upon his arrival in
Israel he changed in Simha Rotem to symbolize a new beginning. His heroic and history is full of anecdotes that
encroach of the unbelievable. Rotem came in and out of the ghetto, through the city’s sewers, besieged and burned, to
bringing news and organizing the escape of the few survivors. Thanks to him the last fighters of the ghetto succeeded in
acriding the “Aryan” area of the city, finding refuge from not Jewish people connected with the Polish resistance. In
1944 Rotem fighted in the Warsaw uprising against the Nazi occupation. He was one of the leader of the Jewish exodus
from Poland to Israel. He contributed to save thousands of people. The author died in Jerusalem in 2018
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