
Johannes A. BuchmannTechnical University of Darmstadt | TU
Johannes A. Buchmann
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Publications (392)
Transcranial direct current stimulation (tDCS) remains experimental for many psychiatric disorders in adults. Particularly in childhood, there is limited research on the evidence for the efficacy and mechanisms of action of tDCS on the developing brain. The objective of this review is to identify published experimental studies to examine the effica...
Dieses Kapitel bietet eine Zusammenfassung der psychiatrischen Symptomatiken die durch Einwirkung externer Noxen wie Entzündungen, Traumata, genetische bedingte Stoffwechselstörungen oder Drogen auf des kindliche Gehirn entstehen können. Dargestellt werden die altersabhängigen klinischen Erscheinungsbilder, ihre Diagnostik und Differenzialdiagnosti...
Background Epicondylopathia humeri radialis is often diagnosed by general practitioners. Usually, the therapy comprises transcutaneous electrical nerve stimulation using a forearm brace. Manual therapy, performed by specialised physiotherapists, is prescribed before transcutaneous electrical nerve stimulation and forearm brace use. However, studies...
Objective:
Electroconvulsive therapy (ECT) is a well-established, safe, and efficacious treatment for severe psychiatric disorders. In children and adolescents, it is used much less frequently than in adults, likely because of a lack of knowledge.
Methods:
We retrospectively analyzed all patients aged 12 to 17 years who completed a course of ECT...
Objective: Disturbed regulation of vigilance in the wake state seems to play a key role in the development of mental disorders. It is assumed that hyperactivity in adult ADHD is an attempt to increase a general low vigilance level via external stimulation in order to avoid drowsiness. For depression, the avoidance of stimulation is interpreted as a...
Neuromuscular diseases are sometimes challenging in diagnosis, often associated with progressive symptoms. In rare cases, there are treatable reasons. We report about a 11-year-old female adolescent who developed subacute progressive paralysis over nearly half a year ago. She was presented to our department as a case of psychosomatic disease. After...
Zusammenfassung. Hintergrund und Zielsetzung: Die Elektrokonvulsionstherapie (EKT) ist ein hoch wirksames und in der Erwachsenenpsychiatrie gut untersuchtes Therapieverfahren, das gerade bei schwerwiegenden depressiven und psychotischen Erkrankungen erfolgreich eingesetzt wird. Obwohl schwere Krankheitsverläufe auch im kinder- und jugendpsychiatris...
Background: Epicondylopathia humeri radialis is often diagnosed by general practitioners. Usually, the therapy comprises transcutaneous electrical nerve stimulation and the application of a forearm brace. Manual therapy is prescribed beyond transcutaneous electrical nerve stimulation and forearm brace, and it is performed by specialized physiothera...
Cryptography is a fundamental tool for cybersecurity and privacy which must be protected for long periods of time. However, the security of most cryptographic algorithms relies on complexity assumptions that may become invalid over time. In this talk I discuss how sustainable cybersecurity and privacy can be achieved in this situation.
A canonical identification (CID) scheme is a 3-move protocol consisting of a commitment, challenge, and response. It constitutes the core design of many cryptographic constructions such as zero-knowledge proof systems and various types of signature schemes. Unlike number-theoretic constructions, CID in the lattice setting usually forces provers to...
Blind signatures constitute basic cryptographic ingredients for privacy-preserving applications such as anonymous credentials, e-voting, and Bitcoin. Despite the great variety of cryptographic applications blind signatures also found their way in real-world scenarios. Due to the expected progress in cryptanalysis using quantum computers, it remains...
Abstract An increasing amount of information today is generated, exchanged, and stored digitally. This also includes long-lived and highly sensitive information (e.g., electronic health records, governmental documents) whose integrity and confidentiality must be protected over decades or even centuries. While there is a vast amount of cryptography-...
Zusammenfassung
Wir berichten über vier Patienten im Alter von 12 bis 17 Jahren mit schizophrenen Psychosen, zwei davon mit katatoner Symptomatik, die erfolgreich und sicher mit Elektrokonvulsionstherapie (EKT) behandelt wurden. Unter einer kombinierten Therapie aus EKT und entweder Ziprasidon oder Clozapin verbesserte sich der Zustand aller Patien...
This book presents refereed proceedings of the First International Conference on Algebra, Codes and Cryptology, A2C 2019, held in Dakar, Senegal, in December 2019.
The 14 full papers were carefully reviewed and selected from 35 submissions. The papers are organized in topical sections on non-associative and non-commutative algebra; code, cryptolog...
Genomic data is crucial in the understanding of many diseases and for the guidance of medical treatments. Pharmacogenomics and cancer genomics are just two areas in precision medicine of rapidly growing utilization. At the same time, whole-genome sequencing costs are plummeting below $ 1000, meaning that a rapid growth in full-genome data storage r...
Distributed storage systems using secret sharing enable information-theoretic confidentiality, making them especially suitable for the outsourced storage of sensitive data. In particular, proactive secret sharing enhances the confidentiality protection of such systems by periodically renewing data shares. This adds a time constraint for an attacker...
In cloud computing, delegated computing raises the security issue of guaranteeing data authenticity during a remote computation. In this context, the recently introduced function-dependent commitments (FDCs) are the only approach providing both fast correctness verification, information-theoretic input-output privacy, and strong unforgeability. Hom...
A large amount of sensitive data must remain accessible for decades or even centuries (e.g, electronic health records, governmental documents). Communicating such data over the Internet requires long-term secure communication channels, which, in turn, require robust key distribution protocols. Currently used key distribution protocols, however, are...
Proactive secret sharing has been proposed by Herzberg, Jarecki, Krawczyk, and Yung (CRYPTO’95) and is a powerful tool for storing highly confidential data. However, their scheme is not designed for storing large data and communication and computation costs scale linearly with the data size. In this paper we propose a variant of their scheme that u...
An increasing amount of information today is generated, exchanged, and stored digitally. This also includes long-lived and highly sensitive information (e.g., electronic health records, governmental documents) whose integrity and confidentiality must be protected over decades or even centuries. While there is a vast amount of cryptography-based dat...
Objective
This study investigated simultaneously the impact of methylphenidate (MPH) on the interaction of inhibitory and facilitative pathways in regions processing motor and cognitive functions.
Method
Neural markers of attention and response control (event‐related potentials) and motor cortical excitability (transcranial magnetic stimulation) a...
The destructive effects of cyber-attacks demand more proactive security approaches. One such promising approach is the idea of Collaborative Intrusion Detection Systems (CIDSs). These systems combine the knowledge of multiple sensors (e.g., intrusion detection systems, honeypots or firewalls) to create a holistic picture of a monitored network. Sen...
In view of the expected cryptanalysis (of both classical and quantum adversaries), it is important to find alternatives for currently used cryptographic primitives. In the past years, several authenticated key exchange protocols (AKE) that base their security on presumably quantum hard problems, such as lattice-based AKEs, were proposed. Since very...
An increasing amount of information today is generated, exchanged, and stored digitally. This also includes long-lived and highly sensitive information (e.g., electronic health records, governmental documents) whose integrity and confidentiality must be protected over decades or even centuries. While there is a vast amount of cryptography-based dat...
Paroxysmal non-epileptic events (PNEE) are highly prevalent among children and youth. Psychogenic seizures, a subgroup of PNEE, affect girls more often than boys and manifest themselves predominantly during adolescence. Different treatments, such as cognitive behavior therapy and psychoeducation, have been applied successfully on patients who are o...
This is part 2 of IEEE Security & Privacy magazine’s special issue on Postquantum Cryptography. As explained in the introduction to part 1, public-key cryptography is indispensable for the security of open computer networks, particularly the Internet. Because of public-key cryptography’s relevance and quantum computers’ increasingly realistic threa...
In cloud computing, delegated computing raises the security issue of guaranteeing data authenticity during a remote computation. Existing solutions do not simultaneously provide fast correctness verification, strong security properties, and information-theoretic confidentiality. We introduce a novel approach, in the form of function-dependent commi...
The Learning With Errors (LWE) problem is one of the most important hardness
assumptions lattice-based constructions base their security on. In 2015,
Albrecht, Player and Scott presented the
software tool LWE-Estimator to estimate the hardness of concrete LWE
instances, making the choice of parameters for lattice-based primitives easier
and better...
Electroconvulsive Therapy (ECT) of a 15-year-old female patient suffering from a severe delusional depression: a case report Abstract.
Objective:
Electroconvulsive Therapy (ECT) is a modern therapy of severe psychiatric disorders. However, ECT is rarely used in treating children and adolescents with psychiatric disorders. This case report refers...
Blockchain technology has arisen as a promising protocol to replace centralized and less efficient systems. In fact, for the first time, it is possible to achieve decentralized consensus without the need for trusted authorities, resulting in more efficient processes and saving both money and time.
Ausgeprägte Abweichungen des zirkadianen Rhythmus finden sich in einer Reihe psychiatrischer Störungsbilder, z.B. bei Schizophrenie, Angststörung oder ADHS (1). Nicht nur therapeutisch werden die häufig berichteten zirkadianen Beschwerden der Betroffenen bisher wenig oder gar nicht berücksichtigt. Die konkreten Zusammenhänge zwischen zirkadianem Rh...
The amount of electronically stored information increases rapidly. Sensitive information requires integrity and confidentiality protection, sometimes for decades or even centuries (e.g., health records or governmental documents). Commonly used cryptographic schemes, however, are not designed to provide protection over such long time periods. Their...
Hierarchical secret sharing schemes distribute a message to a set of shareholders with different reconstruction capabilities. In distributed storage systems, this is an important property because it allows to grant more reconstruction capability to better performing storage servers and vice versa. In particular, Tassa’s conjunctive and disjunctive...
In contrast to classical signature schemes, such as RSA or ECDSA signatures, the lattice-based signature scheme ring-TESLA is expected to be resistant even against quantum adversaries. Due to a recent key recovery from a lattice-based implementation, it becomes clear that cache side channels are a serious threat for lattice-based implementations. I...
Several recent cryptographic constructions – including a public key encryption scheme, a fully homomorphic encryption scheme, and a candidate multilinear map construction – rely on the hardness of the short generator principal ideal problem (SG-PIP): given a \(\mathbb {Z}\)-basis of some principal (fractional) ideal in an algebraic number field tha...
Sensitive digital data, such as health information or governmental archives, are often stored for decades or centuries. The processing of such data calls for long-term security. Secure channels on the Internet require robust key establishment methods. Currently used key distribution protocols are either vulnerable to future attacks based on Shor's...
An increasing amount of information today is generated, exchanged, and stored electronically. This is includes sensitive information such as health records or governmental documents whose integrity and confidentiality must be protected over decades or even centuries. Commonly used cryptographic schemes, however, are not designed to provide protecti...
The lifetime of commonly used digital signature schemes is limited because their security is based on computational assumptions that potentially break in the future. In 1993, Bayer et al. suggested that the lifetime of a digital signature can be prolonged by time-stamping the signature together with the signed document. Based on this idea, various...
Introduction
Event related potentials (ERPs) allow the examination of sensory, attentional and cognitive processes occurring as brain responses to stimuli while the excitability of motor pathways can be evaluated by transcranial magnetic stimulation (TMS).
The interplay between both, attentional processes and motor cortex excitability has been rare...
Because of the concise functionality of oblivious transfer (OT) protocols, they have been widely used as building blocks in secure multiparty computation and high-level protocols. The security of OT protocols built upon classical number theoretic problems, such as the discrete logarithm and factoring, however, is threatened as a result of the huge...
Current trends in technology, such as cloud computing, allow outsourcing the storage, backup, and archiving of data. This provides efficiency and flexibility, but also poses new risks for data security. It in particular became crucial to develop protection schemes that ensure security even in the long-term, i.e. beyond the lifetime of keys, certifi...
It is practically impossible for users to memorize a large portfolio of strong and individual passwords for their online accounts. A solution is to generate passwords randomly and store them. Yet, storing passwords instead of memorizing them bears the risk of loss, e.g., in situations where the device on which the passwords are stored is damaged ,...
We study a scheme of Bai and Galbraith (CT-RSA’14), also known as TESLA. TESLA was thought to have a tight security reduction from the learning with errors problem (LWE) in the random oracle model (ROM). Moreover, a variant using chameleon hash functions was lifted to the quantum random oracle model (QROM). However, both reductions were later found...
Cryptographic commitments are either unconditionally hiding or unconditionally binding, but cannot be both. As a consequence, the security of commonly used commitment schemes is threatened in the long-term, when adversaries become computationally much more powerful. We improve over this situation by putting forward a new notion of commitment scheme...
In diesem Kapitel werden klinische Fälle aus verschiedenen Fachgebieten vorgestellt. Erfahrene Autoren stellen aus ihrer jahrzehntelangen Erfahrung Kasuistiken vor, die sich typsicherweise manualmedizinisch behandeln lassen. Wesentlicher Aspekt dieses Kapitels ist es, die unterschiedlichen klinischen Symptome differenzialdiagnostisch und manualmedi...
It is practically impossible for users to memorize a large portfolio of strong and individual passwords for their online accounts. A solution is to generate passwords randomly and store them. Yet, storing passwords instead of memorizing them bears the risk of loss, e.g., in situations where the device on which the passwords are stored is damaged, l...
The amount of digital data that requires long-term protection of integrity, authenticity, and confidentiality grows rapidly. Examples include electronic health records, genome data, and tax data. In this paper we present the secure storage system LINCOS, which provides protection of integrity, authenticity, and confidentiality in the long-term, i.e...
Current trends in technology, such as cloud computing, allow outsourcing the storage, backup, and archiving of data. This provides efficiency and flexibility, but also poses new risks for data security. It in particular became crucial to develop protection schemes that ensure security even in the long-term, i.e. beyond the lifetime of keys, certifi...
In addition to proof or argument based verifiable computing schemes and constructions that rely on homomorphic encryption or homomorphic authenticators, verifiable computing schemes can also be constructed using functional encryption or functional signatures. Thus, in this chapter we present the verifiable computing schemes using one of these primi...
In this chapter we discuss approaches to verifiable computing that use fully homomorphic encryption (FHE) as a building block. First, we define homomorphic encryption and fully homomorphic encryption. Then, we describe the verifiable computing schemes using this primitive, i.e. “Non-Interactive Verifiable Computing: Outsourcing Computation to Untru...
In this chapter we provide formal definitions for verifiable computing schemes and their relevant properties. More precisely, first, we define verifiable computing schemes in general and privately verifiable computing schemes and publicly verifiable computing schemes in particular. Then, we provide a definition for weak and adaptive security. Follo...
Beyond the families of schemes we have seen so far, there exist verifiable computing schemes for specific functions, which we present here. More precisely, “From Secrecy to Soundness: Efficient Verification via Secure Computation” by Applebaum et al. allows the computation of arithmetic branching programs, “Signatures of Correct Computation” by Pap...
In this chapter, all verifiable computing schemes discussed in this survey are summarized and their properties are highlighted. We first summarize for each type of verifiable computing scheme presented in the survey, i.e. proof and argument based verifiable computing, verifiable computing from fully homomorphic encryption, homomorphic authenticator...
Homomorphic authenticators allow to evaluate functions on authenticated data. There exist constructions both in the secret key setting in the form of homomorphic message authentication codes (MACs) and in the public key setting in the form of homomorphic signatures. These solutions can be used to respectively construct privately and publicly verifi...
In this chapter the state of the art with respect to proof based verifiable computing schemes is presented. In this setting a prover wants to convince a verifier of the correctness of a computed result. The first proof based solutions that achieve this were interactive proof systems. Depending on the computation power of the prover we distinguish h...
This work shows that the field of verifiable computing, although not very old, has made huge improvements over the last years. Various solutions have been found for different function classes.
ZBTB18 has been proposed as candidate gene for microcephaly and abnormalities of the corpus callosum based on overlapping microdeletions of 1q43q44. More recently, de novo mutations of ZBTB18 have been identified in patients with syndromic and non-syndromic intellectual disability. Heterozygous microdeletions of 15q13.3 encompassing the candidate g...
In this work the first linearly homomorphic authenticated encryption scheme with public verifiability and provable correctness, called \(\mathsf {LEPCoV}\), is presented. It improves the initial proposal by avoiding false negatives during the verification algorithm. This work provides a detailed description of \(\mathsf {LEPCoV}\), a comparison wit...
Code-based cryptosystems are promising candidates for post-quantum cryptography since they are fast, require only basic arithmetic because their security is well understood. The increasing number of cryptographic schemes based on codes over fields other than F2 presents, however, security issues that are not relevant in the case of binary codes; th...
This book presents the first comprehensive overview of various verifiable computing techniques, which allow the computation of a function on outsourced data to be delegated to a server. It provides a brief description of all the approaches and highlights the properties each solution achieves. Further, it analyzes the level of security provided, how...
Because of public-key cryptography’s relevance and quantum computers’ increasingly realistic threat to this technology, it’s necessary to come up with practical and secure postquantum cryptography. This special issue aims to present the state of the art and the grand challenges in postquantum cryptography and to discuss the transition of real-world...
The unavoidable transition to post-quantum cryptography requires dependable quantum-safe digital signature schemes. Hash-based signatures are well-understood and promising candidates, and the object of current standardization efforts. In the scope of this standardization process, the most commonly raised concern is statefulness, due to the use of o...
Password-based authentication is the most widely used authentication scheme for granting access to user accounts on the Internet. Despite this, there exists no standard implementation of passwords by services. They have different password requirements as well as interfaces and procedures for login, password change, and password reset. This situatio...
Data processing within large organisations is often complex, impeding both the traceability of data and the compliance of processing with usage policies. The chronology of the ownership, custody, or location of data—its provenance—provides the necessary information to restore traceability. However, to be of practical use, provenance records should...
In this work we provide a framework for dynamic secret sharing and present the first dynamic and verifiable hierarchical secret sharing scheme based on Birkhoff interpolation. Since the scheme is dynamic it allows, without reconstructing the message distributed, to add and remove shareholders, to renew shares, and to modify the conditions for acces...
Due to their high efficiency and their strong security properties, lattice-based cryptographic schemes seem to be a very promising post-quantum replacement for currently used public key cryptography. The security of lattice-based schemes has been deeply analyzed mathematically, whereas little effort has been spent on the analysis against implementa...
Digital archiving systems are necessary to store documents for several years, such as electronic health records. However, security breaches in these systems may allow attackers to tamper with archived documents without being noticed. To address this threat, standardized archiving systems require a public key infrastructure, where a time-stamp autho...
Passwords are the most widely used authentication scheme for granting access to user accounts on the Internet. In order to choose strong passwords, security experts recommend the usage of password generators. However, automatically generated passwords often get rejected by services, because they do not fulfill the services’ password requirements. U...
Practical hardness results are necessary to select parameters for cryptographic schemes. Cryptographic challenges proved to be useful for determining the practical hardness of computational problems that are used to build public-key cryptography. However, several of these problems have the drawback that it is not known how to create a challenge for...
In the emerging Internet of Things, lightweight public-key cryptography is an essential component for many cost-efficient security solutions. Since conventional public-key schemes, such as ECC and RSA, remain expensive and energy hungry even after aggressive optimization, this work investigates a possible alternative. In particular, we show the pra...
The security of many cryptographic schemes has been based on special instances of the Learning with Errors (LWE) problem, e.g., Ring-LWE, LWE with binary secret, or LWE with ternary error. However, recent results show that some subclasses are weaker than expected. In this work we show that LWE with binary error, introduced by Micciancio and Peikert...
In view of the expected progress in cryptanalysis it is important to find alternatives for currently used signature schemes such as RSA and ECDSA. The most promising lattice-based signature schemes to replace these schemes are (CRYPTO 2013) and GLP (CHES 2012). Both come with a security reduction from a lattice problem and have high performance. Ho...
Homomorphic signature schemes are an important primitive for many applications and since their introduction numerous solutions have been presented. Thus, in this work we provide the first exhaustive, complete, and up-to-date survey about the state of the art of homomorphic signature schemes. First, the general framework where homomorphic signatures...