Hash-based signatures for the internet of things

While numerous digital signature schemes exist in the literature, most real-world system rely on RSA-based signature schemes or on the digital signature algorithm (DSA), including its elliptic curve cryptography variant ECDSA. In this position paper we review a family of alternative signature schemes, based on hash functions, and we make the case for their application in Internet of Things (IoT) settings. Hash-based signatures provide postquantum security, and only make minimal security assumptions, in general requiring only a secure cryptographic hash function. This makes them extremely flexible, as they can be implemented on top of any hash function that satisfies basic security properties. Hash-based signatures also feature numerous parameters defining aspects such as signing speed and key size, that enable trade-offs in constrained environments. Simplicity of implementation and customization make hash based signatures an attractive candidate for the IoT ecosystem, which is composed of a number of diverse, constrained devices

PaaSword: A Data Privacy and Context-aware Security Framework for Developing Secure Cloud Applications - Technical and Scientific Contributions

Most industries worldwide have entered a period of reaping the benefits and opportunities cloud offers. At the same time, many efforts are made to address engineering challenges for the secure development of cloud systems and software.With the majority of software engineering projects today relying on the cloud, the task to structure end-to-end secure-by-design cloud systems becomes challenging but at the same time mandatory. The PaaSword project has been commissioned to address security and data privacy in a holistic way by proposing a context-aware security-by-design framework to support software developers in constructing secure applications for the cloud. This chapter presents an overview of the PaaSword project results, including the scientific achievements as well as the description of the technical solution. The benefits offered by the framework are validated through two pilot implementations and conclusions are drawn based on the future research challenges which are discussed in a research agenda

Post-quantum cryptography

Cryptography is essential for the security of online communication, cars and implanted medical devices. However, many commonly used cryptosystems will be completely broken once large quantum computers exist. Post-quantum cryptography is cryptography under the assumption that the attacker has a large quantum computer; post-quantum cryptosystems strive to remain secure even in this scenario. This relatively young research area has seen some successes in identifying mathematical operations for which quantum algorithms offer little advantage in speed, and then building cryptographic systems around those. The central challenge in post-quantum cryptography is to meet demands for cryptographic usability and flexibility without sacrificing confidence.</p

Multi-Armed SPHINCS+

Hash-based signatures are a type of Digital Signature Algorithms that are positioned as one of the most solid quantum-resistant constructions. As an example SPHINCS+, has been selected as a standard during the NIST Post-Quantum Cryptography competition. However, hash-based signatures suffer from two main drawbacks: signature size and slow signing process. In this work, we give a solution to the latter when it is used in a mobile device. We take advantage of the fact that hash-based signatures are highly parallelizable. More precisely, we provide an implementation of SPHINCS+ on the Snapdragon 865 Mobile Platform taking advantage of its eight CPUs and their vector extensions. Our implementation shows that it is possible to have a speed-up of 15 times when compared to a purely sequential and non-vectorized implementation. Furthermore, we evaluate the performance impact of side-channel protection using vector extensions in the SPHINCS+ version based on SHAKE

Planning and Evaluation of Information Security Investments

This thesis provides a theory-based understanding of information security investments within organizations concentrating on organizational planning and evaluation of information security investments. The underlying framework is the Cyber Security Investment Framework of Rowe and Gallaher (2006). This work is structured as follows: In Part I, the dissertation is motivated and the theory to frame this research is described in detail. Subsequently, in Part II, the publications which comprise this thesis are presented. Finally, in Part III, the fi�ndings of this dissertation are discussed

Fiat-Shamir signatures without aborts using Ring-and-Noise assumptions

Lattice and code based hard problems such as Learning With Errors (LWE) or syndrome decoding (SD) form cornerstones of post-quantum cryptography. However, signature schemes built on these assumptions remain rather complicated. Indeed, signature schemes from LWE problems are built on the Fiat-Shamir with abort paradigm with no apparent means for knowledge extraction. On the code side, signature schemes mainly stem from Stern\u27s zero-knowledge identification scheme. However, because of its large soundness error of $2/3$, it is costly to turn into a signature scheme. The latest developments rely on complicated cut-and-choose and multiparty-in-the-head techniques. As a consequence, they apply the Fiat-Shamir transformation on protocols with at least 5 rounds, leading to additional complexity and degraded security parameters. In the present paper, we propose an alternative approach to build a simple zero-knowledge $\Sigma$-protocol with a small soundness error, based on the hardness of Ring-and-Noise assumptions, a general family of assumptions that encompasses both lattices and codes. With such a $\Sigma$-protocol at hand, signatures can directly be derived by invoking the standard Fiat-Shamir transform, without the need for aborts. The main novel tool that allows us to achieve this is the use of specifically tailored locality sensitive hash functions. We outline our schemes for general Ring-and-Noise assumptions and present them in detail for the ring of residues modulo Mersenne numbers endowed with the Hamming metric. This Mersenne setting is ideal to illustrate our schemes, since it is close in spirit to both lattice and code based assumptions

An Overview of Hash Based Signatures

Digital signatures are one of the most basic cryptographic building blocks which are utilized to provide attractive security features like authenticity, unforgeability, and undeniability. The security of existing state of the art digital signatures is based on hardness of number theoretic hardness assumptions like discrete logarithm and integer factorization. However, these hard problems are insecure and face a threat in the quantum world. In particular, quantum algorithms like Shor’s algorithm can be used to solve the above mentioned hardness problem in polynomial time. As an alternative, a new direction of research called post-quantum cryptography (PQC) is supposed to provide a new generation of quantum-resistant digital signatures. Hash based signature is one such candidate to provide post quantum secure digital signatures. Hash based signature schemes are a type of digital signature scheme that use hash functions as their central building block. They are efficient, flexible, and can be used in a variety of applications. In this document, we provide an overview of the hash based signatures. Our presentation of the topic covers a wide range of aspects that are not only comprehensible for readers without expertise in the subject matter, but also serve as a valuable resource for experts seeking reference material