Rationale, design and conduct of a randomised controlled trial evaluating a primary care-based complex intervention to improve the quality of life of heart failure patients: HICMan (Heidelberg Integrated Case Management) : study protocol

Background: Chronic congestive heart failure (CHF) is a complex disease with rising prevalence, compromised quality of life (QoL), unplanned hospital admissions, high mortality and therefore high burden of illness. The delivery of care for these patients has been criticized and new strategies addressing crucial domains of care have been shown to be effective on patients' health outcomes, although these trials were conducted in secondary care or in highly organised Health Maintenance Organisations. It remains unclear whether a comprehensive primary care-based case management for the treating general practitioner (GP) can improve patients' QoL. Methods/Design: HICMan is a randomised controlled trial with patients as the unit of randomisation. Aim is to evaluate a structured, standardized and comprehensive complex intervention for patients with CHF in a 12-months follow-up trial. Patients from intervention group receive specific patient leaflets and documentation booklets as well as regular monitoring and screening by a prior trained practice nurse, who gives feedback to the GP upon urgency. Monitoring and screening address aspects of disease-specific selfmanagement, (non)pharmacological adherence and psychosomatic and geriatric comorbidity. GPs are invited to provide a tailored structured counselling 4 times during the trial and receive an additional feedback on pharmacotherapy relevant to prognosis (data of baseline documentation). Patients from control group receive usual care by their GPs, who were introduced to guidelineoriented management and a tailored health counselling concept. Main outcome measurement for patients' QoL is the scale physical functioning of the SF-36 health questionnaire in a 12-month follow-up. Secondary outcomes are the disease specific QoL measured by the Kansas City Cardiomyopathy questionnaire (KCCQ), depression and anxiety disorders (PHQ-9, GAD-7), adherence (EHFScBS and SANA), quality of care measured by an adapted version of the Patient Chronic Illness Assessment of Care questionnaire (PACIC) and NTproBNP. In addition, comprehensive clinical data are collected about health status, comorbidity, medication and health care utilisation. Discussion: As the targeted patient group is mostly cared for and treated by GPs, a comprehensive primary care-based guideline implementation including somatic, psychosomatic and organisational aspects of the delivery of care (HICMAn) is a promising intervention applying proven strategies for optimal care. Trial registration: Current Controlled Trials ISRCTN30822978

Information-set decoding for linear codes over Fq

A code-based cryptosystem is considered secure if the best known attack against it is information-set decoding. Stern’s algorithm and its improvements are well optimized and the complexity is reasonably well understood. However, these algorithms only handle codes over F2. This paper presents a generalization of Stern’s information-set-decoding algorithm for decoding linear codes over arbitrary finite fields Fq and analyzes the complexity. This result makes it possible to compute the security of recently proposed code-based systems over non-binary fields. As an illustration, ranges of parameters for generalized McEliece cryptosystems using classical Goppa codes over F31 are suggested for which the new information-set-decoding algorithm needs 2 128 bit operations

Ball-collision decoding

This paper introduces a new generic decoding algorithm that is asymptotically faster than any previous attack against the McEliece cryptosystem. At a 256-bit security level, the attack costs 2.6 times fewer bit operations than the best previous attack; at a theoretical 1000-bit security level, the attack costs 15.5 times fewer bit operations than the best previous attack. The algorithm is asymptotically even faster than the Finiasz-Sendrier lower bound published at Asiacrypt 2009, demonstrating that the Finiasz-Sendrier parameter recommendations are not as secure as claimed. This paper proposes much safer, but still reasonably efficient, parameters based on an analysis of the fundamental bottleneck in all algorithms of this type

Wild McEliece

The original McEliece cryptosystem uses length-$n$ codes over $\rm{F}_2$ with dimension $\geq n-mt$ efficiently correcting t errors where $2^m \geq n$. This paper presents a generalized cryptosystem that uses length-$n$ codes over small finite fields $\rm{F}_q$ with dimension $\geq n-m(q-1)t$ efficiently correcting $\lfloor qt/2 \rfloor$ errors where $q^m \geq n$. Previously proposed cryptosystems with the same length and dimension corrected only $\lfloor (q-1)t/2 \rfloor$ errors for $q \geq 3$. This paper also presents list-decoding algorithms that efficiently correct even more errors for the same codes over $\rm{F}_q$. Finally, this paper shows that the increase from $\lfloor (q-1)t/2 \rfloor$ errors to more than $\lfloor qt/2 \rfloor$ errors allows considerably smaller keys to achieve the same security level against all known attacks. Keywords: McEliece cryptosystem, Niederreiter cryptosystem, Goppa codes, wild Goppa codes, list decoding

Faster 2-regular information-set decoding

Fix positive integers B and w. Let C be a linear code over F_2 of length Bw. The 2-regular-decoding problem is to find a nonzero codeword consisting of w length-B blocks, each of which has Hamming weight 0 or 2. This problem appears in attacks on the FSB (fast syndrome-based) hash function and related proposals. This problem differs from the usual information-set-decoding problems in that (1) the target codeword is required to have a very regular structure and (2) the target weight can be rather high, so that there are many possible codewords of that weight. Augot, Finiasz, and Sendrier, in the paper that introduced FSB, presented a variant of information-set decoding tuned for 2-regular decoding. This paper improves the Augot–Finiasz–Sendrier algorithm in a way that is analogous to Stern's improvement upon basic information-set decoding. The resulting algorithm achieves an exponential speedup over the previous algorithm

Explicit bounds for generic decoding algorithms for code-based cryptography

No abstract