A limitation on security evaluation of cryptographic primitives with fixed keys

In this paper, we discuss security of public‐key cryptographic primitives in the case that the public key is fixed. In the standard argument, security of cryptographic primitives are evaluated by estimating the average probability of being successfully attacked where keys are treated as random variables. In contrast to this, in practice, a user is mostly interested in the security under his specific public key, which has been already fixed. However, it is obvious that such security cannot be mathematically guaranteed because for any given public key, there always potentially exists an adversary, which breaks its security. Therefore, the best what we can do is just to use a public key such that its effective adversary is not likely to be constructed in the real life and, thus, it is desired to provide a method for evaluating this possibility. The motivation of this work is to investigate (in)feasibility of predicting whether for a given fixed public key, its successful adversary will actually appear in the real life or not. As our main result, we prove that for any digital signature scheme or public key encryption scheme, it is impossible to reduce any fixed key adversary in any weaker security notion than the de facto ones (i.e., existential unforgery against adaptive chosen message attacks or indistinguishability against adaptive chosen ciphertext attacks) to fixed key adversaries in the de facto security notion in a black‐box manner. This result means that, for example, for any digital signature scheme, impossibility of extracting the secret key from a fixed public key will never imply existential unforgery against chosen message attacks under the same key as long as we consider only black‐box analysis

High Reynolds Number Flow in Capillary Tube with Spiral/Bend Portion (Experimental Results for Water)

Experimental study on water flow in capillary tubes with straight, bent, or coiled portion is conducted. Stainless tubes with nominal diameter of 0.5mm, 0.25mm, and 0.1mm are examined at several temperatures. Reynolds number ranges from 30 to 16000, where maximum velocity becomes up to 30m/s. Pressure loss of test piece and discharge flow rate are measured to be compared with the results from previous studies. In spite of considerable roughness of capillary inner surface, measured data do not indicate roughness effect explicitly. Laminar friction factors for coiled tubes show the clear dependence on the number of turns in the coil, which cannot be explained by previous studies. Empirical equations for examined capillary contours are obtained

Re-encryption Verifiability: How to Detect Malicious Activities of a Proxy in Proxy Re-encryption

In this paper, we introduce a new functionality for proxy re-encryption (PRE) that we call re-encryption verifiability. In a PRE scheme with re-encryption verifiability (which we simply call verifiable PRE, or VPRE), a receiver of a re-encrypted ciphertext can verify whether the received ciphertext is correctly transformed from an original ciphertext by a proxy, and thus can detect illegal activities of the proxy. We formalize the security model for a VPRE scheme, and show that the single-hop uni-directional PRE scheme by Hanaoka et al. (CT-RSA 2012) can be extended to a secure VPRE scheme

Group Signatures with Message-Dependent Opening: Formal Definitions and Constructions

This paper introduces a new capability for group signatures called message-dependent opening. It is intended to weaken the high trust placed on the opener; i.e., no anonymity against the opener is provided by an ordinary group signature scheme. In a group signature scheme with message-dependent opening (GS-MDO), in addition to the opener, we set up an admitter that is not able to extract any user’s identity but admits the opener to open signatures by specifying messages where signatures on the specified messages will be opened by the opener. The opener cannot extract the signer’s identity from any signature whose corresponding message is not specified by the admitter. This paper presents formal definitions of GS-MDO and proposes a generic construction of it from identity-based encryption and adaptive non-interactive zero-knowledge proofs. Moreover, we propose two specific constructions, one in the standard model and one in the random oracle model. Our scheme in the standard model is an instantiation of our generic construction but the message-dependent opening property is bounded. In contrast, our scheme in the random oracle model is not a direct instantiation of our generic construction but is optimized to increase efficiency and achieves the unbounded message-dependent opening property. Furthermore, we also demonstrate that GS-MDO implies identity-based encryption, thus implying that identity-based encryption is essential for designing GS-MDO schemes

Ischemic and Bleeding Risk After Percutaneous Coronary Intervention in Patients With Prior Ischemic and Hemorrhagic Stroke

Background: Prior stroke is regarded as risk factor for bleeding after percutaneous coronary intervention (PCI). However, there is a paucity of data on detailed bleeding risk of patients with prior hemorrhagic and ischemic strokes after PCI. Methods and Results: In a pooled cohort of 19 475 patients from 3 Japanese PCI studies, we assessed the influence of prior hemorrhagic (n=285) or ischemic stroke (n=1773) relative to no-prior stroke (n=17 417) on ischemic and bleeding outcomes after PCI. Cumulative 3-year incidences of the co-primary bleeding end points of intracranial hemorrhage, non-intracranial global utilization of streptokinase and tissue plasminogen activator for occluded coronary arteries (GUSTO) moderate/severe bleeding, and the primary ischemic end point of ischemic stroke/myocardial infarction were higher in the prior hemorrhagic and ischemic stroke groups than in the no-prior stroke group (6.8%, 2.5%, and 1.3%, P<0.0001, 8.8%, 8.0%, and 6.0%, P=0.001, and 12.7%, 13.4%, and 7.5%, P<0.0001). After adjusting confounders, the excess risks of both prior hemorrhagic and ischemic strokes relative to no-prior stroke remained significant for intracranial hemorrhage (hazard ratio (HR) 4.44, 95% CI 2.64-7.01, P<0.0001, and HR 1.52, 95% CI 1.06-2.12, P=0.02), but not for non-intracranial bleeding (HR 1.18, 95% CI 0.76-1.73, P=0.44, and HR 0.94, 95% CI 0.78-1.13, P=0.53). The excess risks of both prior hemorrhagic and ischemic strokes relative to no-prior stroke remained significant for ischemic events mainly driven by the higher risk for ischemic stroke (HR 1.46, 95% CI 1.02-2.01, P=0.04, and HR 1.49, 95% CI 1.29-1.72, P<0.0001). Conclusions: Patients with prior hemorrhagic or ischemic stroke as compared with those with no-prior stroke had higher risk for intracranial hemorrhage and ischemic events, but not for non-intracranial bleeding after PCI

Details on the effect of very short dual antiplatelet therapy after drug-eluting stent implantation in patients with high bleeding risk: insight from the STOPDAPT-2 trial

Previously we briefly reported the effect of 1-month dual antiplatelet therapy (DAPT) for patients with high bleeding risk (HBR) receiving percutaneous coronary intervention (PCI) in the STOPDAPT-2 trial, but full analysis data have not been available. We conducted post hoc subgroup analysis regarding the effect of very short DAPT for HBR patients in STOPDAPT-2 trial. The primary endpoint was a 1-year composite of cardiovascular (cardiovascular death, myocardial infarction, definite stent thrombosis, or stroke) and bleeding (TIMI major/minor bleeding) outcomes. Major secondary endpoints were 1-year cardiovascular composite endpoint and bleeding endpoint. HBR was defined by the academic research consortium (ARC) HBR criteria. Among the 3009 study patients, 1054 (35.0%) were classified as HBR and 1955 (65.0%) were as non-HBR. There were no significant interactions between HBR/non-HBR subgroups and the assigned DAPT group on the primary endpoint (HBR; 3.48% vs. 5.98%, HR 0.57, 95% CI 0.32-1.03, and non-HBR; 1.81% vs. 2.36%, HR 0.78, 95% CI 0.42-1.45; P for interaction = 0.48), the major secondary cardiovascular endpoint (HBR; 3.07% vs. 4.03%, HR 0.77, 95% CI 0.40-1.48, and non-HBR; 1.41% vs. 1.61%, HR 0.89, 95% CI 0.43-1.84; P for interaction = 0.77), and the major secondary bleeding endpoint (HBR; 0.41% vs. 2.71%, HR 0.15, 95% CI 0.03-0.65, and non-HBR; 0.40% vs. 0.85%, HR 0.48, 95% CI 0.14-1.58; P for interaction = 0.22). In conclusion, the effects of 1-month DAPT for the primary and major secondary endpoints were consistent in HBR and non-HBR patients without any significant interactions. The benefit of 1-month DAPT in reducing major bleeding was numerically greater in HBR patients.Clinical trial registration Short and optimal duration of dual antiplatelet therapy after everolimus-eluting cobalt-chromium stent-2 [STOPDAPT-2]; NCT02619760

Cognitive behavioral therapy for depression among adults in Japanese clinical settings: a single-group study

<p>Abstract</p> <p>Background</p> <p>Empirical support for cognitive behavioral therapy (CBT) for treating Japanese patients with major depression is lacking, therefore, a feasibility study of CBT for depression in Japanese clinical settings is urgently required.</p> <p>Findings</p> <p>A culturally adapted, 16-week manualized individual CBT program for Japanese patients with major depressive disorder was developed. A total of 27 patients with major depression were enrolled in a single-group study with the purpose of testing the feasibility of the program. Twenty six patients (96%) completed the study. The mean total score on the Beck Depression Inventory-II (BDI-II) for all patients (Intention-to-treat sample) improved from 32.6 to 11.7, with a mean change of 20.8 (95% confidence interval: 17.0 to 24.8). Within-group effect size at the endpoint assessment was 2.64 (Cohen's d). Twenty-one patients (77.7%) showed treatment response and 17 patients (63.0%) achieved remission at the end of the program. Significant improvement was observed in measurement of subjective and objective depression severity (assessed by BDI-II, Quick Inventory of Depressive Symptomatology-Self Rated, and Hamilton Depression Rating Scale), dysfunctional attitude (assessed by Dysfunctional Attitude Scale), global functioning (assessed by Global Assessment of Functioning of DSM-IV) and subjective well-being (assessed by WHO Subjective Well-being Inventory) (all p values < 0.001).</p> <p>Conclusions</p> <p>Our manualized treatment comprised of a 16-week individual CBT program for major depression appears feasible and may achieve favorable treatment outcomes among Japanese patients with major depression. Further research involving a larger sample in a randomized, controlled trial design is warranted.</p> <p>Trial registration</p> <p>UMIN-CTR UMIN000002542.</p

CVIT expert consensus document on primary percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI) in 2018

While primary percutaneous coronary intervention (PCI) has significantly contributed to improve the mortality in patients with ST segment elevation myocardial infarction even in cardiogenic shock, primary PCI is a standard of care in most of Japanese institutions. Whereas there are high numbers of available facilities providing primary PCI in Japan, there are no clear guidelines focusing on procedural aspect of the standardized care. Whilst updated guidelines for the management of acute myocardial infarction were recently published by European Society of Cardiology, the following major changes are indicated; (1) radial access and drug-eluting stent over bare metal stent were recommended as Class I indication, and (2) complete revascularization before hospital discharge (either immediate or staged) is now considered as Class IIa recommendation. Although the primary PCI is consistently recommended in recent and previous guidelines, the device lag from Europe, the frequent usage of coronary imaging modalities in Japan, and the difference in available medical therapy or mechanical support may prevent direct application of European guidelines to Japanese population. The Task Force on Primary Percutaneous Coronary Intervention of the Japanese Association of Cardiovascular Intervention and Therapeutics (CVIT) has now proposed the expert consensus document for the management of acute myocardial infarction focusing on procedural aspect of primary PCI

CVIT expert consensus document on primary percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI) in 2018

While primary percutaneous coronary intervention (PCI) has significantly contributed to improve the mortality in patients with ST segment elevation myocardial infarction even in cardiogenic shock, primary PCI is a standard of care in most of Japanese institutions. Whereas there are high numbers of available facilities providing primary PCI in Japan, there are no clear guidelines focusing on procedural aspect of the standardized care. Whilst updated guidelines for the management of acute myocardial infarction were recently published by European Society of Cardiology, the following major changes are indicated; (1) radial access and drug-eluting stent over bare metal stent were recommended as Class I indication, and (2) complete revascularization before hospital discharge (either immediate or staged) is now considered as Class IIa recommendation. Although the primary PCI is consistently recommended in recent and previous guidelines, the device lag from Europe, the frequent usage of coronary imaging modalities in Japan, and the difference in available medical therapy or mechanical support may prevent direct application of European guidelines to Japanese population. The Task Force on Primary Percutaneous Coronary Intervention of the Japanese Association of Cardiovascular Intervention and Therapeutics (CVIT) has now proposed the expert consensus document for the management of acute myocardial infarction focusing on procedural aspect of primary PCI