Ruhr-Universität Bochum (RUB): Open Journal Systems
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Revisiting delusions to demystify human agency: A response to critics
Get PDFIn this paper, I re-elaborate some of the ideas presented in Why Delusions Matter (Bloomsbury 2023) in response to four commentaries on the book. My proposed conception of delusionality cuts across clinical and non-clinical contexts: an interpreter calls a speaker’s belief delusionalwhen the belief seems to be central to the speaker’s identity, but the interpreter finds it both implausible and unshakeable. Here I frame the emphasis on what all delusional beliefs have in common as an attempt to resist simplistic dichotomies about human agency. Ideal agents seek the truth and accurately represent the world, engaging with it in such a way as to further their goals, exercise control over themselves and the surrounding environment, and successfully coordinate with others. Human agents can sometimes rely on comforting illusions and constructed worlds to establish or restore a connection with other agents and the shared environment at challenging times. But coordination can fail, and control is always limited. Delusions are an expression of agency in the sense that they can be understood as a response to the epistemic and psychological needs of human agents. Delusions are meaningful and may contain germs of truth about the speaker. But they should be replaced when better strategies for engaging with the world become available to the speaker
Book Symposium: "Why Delusions Matter"
No full textThis Symposium aims to contribute to the discussion on "Why Delusions Matter" by Lisa Bortolotti (2023), published by Bloomsbury. In her book, Bortolotti attempts to decouple delusions from pathology, and argues that delusions should not be dismissed as meaningless, because engaging with them at an epistemic level fosters a deeper understanding of the speaker’s perspective and agency. The Symposium opens with a précis of the book (Bortolotti, 2024a), followed by four commentaries that critically engage with Bortolotti’s argument. Bacchi (2024) suggests that insights from the authenticity debate in psychiatry could support Bortolotti’s claim that delusions could foster agency. Drawing from the literature and from her own lived experience with delusions, Russel (2024) explores the ways in which some delusions can be epistemically valuable. Williams (2024) challenges the implication that popular, non-clinical delusions deserve a more positive reputation. Vintiadis (2024) links Bortolotti’s work to the discussion on comforting delusions in psychedelic-assisted psychotherapy. The Symposium concludes with a reply from Bortolotti (2024b)
Religious Conversion as a Form of Religious Contact: Special Issue Introduction
No full textReligious conversion is a phenomenon that has intrigued scholars, theologians, and sociologists for centuries. As the conscious choice of a particular form of religion over another, it is eminently a form of religious contact. Religious conversion may be approached psychologically, sociologically, and conceptually. The contributions of this special issue show all three approaches and cover a wide array of geographical, social, and religious contexts
American Conversions to Eastern Orthodox Christianity
Get PDFThis paper explores conversions to Eastern Orthodox Christianity in the United States. It discusses the analytic value of different categories used to describe American Orthodox Christians; examines theoretic models that best explain American conversions to Orthodoxy; and focuses on American conversions to Orthodoxy as resocialization into a new religious group, which implies the unlearning of certain ideas and practices. The paper is based on data collected by the author in Eastern Orthodox communities in the United States in 2018–2019 and 2024, as well as on the author’s previous cross-cultural observations that shed light on American conversions to Orthodoxy
Permutation-Based Hashing Beyond the Birthday Bound
No full textIt is known that the sponge construction is tightly indifferentiable from a random oracle up to around 2c/2 queries, where c is the capacity. In particular, it cannot provide generic security better than half of the underlying permutation size. In this paper, we aim to achieve hash function security beating this barrier. We present a hashing mode based on two b-bit permutations named the double sponge. The double sponge can be seen as the sponge embedded within the double block length hashing paradigm, making two permutation calls in parallel interleaved with an efficient mixing function. Similarly to the sponge, the permutation size is split as b = r+c, and the underlying compression function absorbs r bits at a time. We prove that the double sponge is indifferentiable from a random oracle up to around 22c/3 queries. This means that the double sponge achieves security beyond the birthday bound in the capacity. In addition, if c > 3b/4, the double sponge beats the birthday bound in the primitive size, to our knowledge being the first hashing mode based on a permutation that accomplices this feature
Solving Degree Bounds for Iterated Polynomial Systems
No full textFor Arithmetization-Oriented ciphers and hash functions Gröbner basis attacks are generally considered as the most competitive attack vector. Unfortunately, the complexity of Gröbner basis algorithms is only understood for special cases, and it is needless to say that these cases do not apply to most cryptographic polynomial systems. Therefore, cryptographers have to resort to experiments, extrapolations and hypotheses to assess the security of their designs. One established measure to quantify the complexity of linear algebra-based Gröbner basis algorithms is the so-called solving degree. Caminata & Gorla revealed that under a certain genericity condition on a polynomial system the solving degree is always upper bounded by the Castelnuovo-Mumford regularity and henceforth by the Macaulay bound, which only takes the degrees and number of variables of the input polynomials into account. In this paper we extend their framework to iterated polynomial systems, the standard polynomial model for symmetric ciphers and hash functions. In particular, we prove solving degree bounds for various attacks on MiMC, Feistel-MiMC, Feistel-MiMC-Hash, Hades and GMiMC. Our bounds fall in line with the hypothesized complexity of Gröbner basis attacks on these designs, and to the best of our knowledge this is the first time that a mathematical proof for these complexities is provided. Moreover, by studying polynomials with degree falls we can prove lower bounds on the Castelnuovo-Mumford regularity for attacks on MiMC, Feistel-MiMC and Feistel-MiMCHash provided that only a few solutions of the corresponding iterated polynomial system originate from the base field. Hence, regularity-based solving degree estimations can never surpass a certain threshold, a desirable property for cryptographic polynomial systems
Constructing Committing and Leakage-Resilient Authenticated Encryption
No full textThe main goal of this work is to construct authenticated encryption (AE) hat is both committing and leakage-resilient. As a first approach for this we consider generic composition as a well-known method for constructing AE schemes. While the leakage resilience of generic composition schemes has already been analyzed by Barwell et al. (Asiacrypt’17), for committing security this is not the case. We fill this gap by providing a separate analysis of the generic composition paradigms with respect to committing security, giving both positive and negative results: By means of a concrete attack, we show that Encrypt-then-MAC is not committing. Furthermore, we prove that Encrypt-and-MAC is committing, given that the underlying schemes satisfy security notions we introduce for this purpose. We later prove these new notions achievable by providing schemes that satisfy them. MAC-then-Encrypt turns out to be more difficult due to the fact that the tag is not outputted alongside the ciphertext as it is done for the other two composition methods. Nevertheless, we give a detailed heuristic analysis of MAC-then-Encrypt with respect to committing security, leaving a definite result as an open task for future work. Our results, in combination with the fact that only Encrypt-then-MAC yields leakage-resilient AE schemes, show that one cannot obtain AE schemes that are both committing and leakage-resilient via generic composition. As a second approach for constructing committing and leakage-resilient AE, we develop a generic transformation that turns an arbitrary AE scheme into one that fulfills both properties. The transformation relies on a keyed function that is both binding, i.e., it is hard to find key-input pairs that result in the same output, and leakage-resilient pseudorandom
FRAST: TFHE-Friendly Cipher Based on Random S-Boxes
No full textA transciphering framework, also known as hybrid homomorphic encryption, is a practical method of combining a homomorphic encryption (HE) scheme with a symmetric cipher in the client-server model to reduce computational and communication overload on the client side. As a server homomorphically evaluates a symmetric cipher in this framework, new design rationales are required for “HE-friendly” ciphers that take into account the specific properties of the HE schemes. In this paper, we propose a new TFHE-friendly cipher, dubbed FRAST, with a TFHE-friendly round function based on a random S-box to minimize the number of rounds. The round function of FRAST can be efficiently evaluated in TFHE by a new optimization technique, dubbed double blind rotation. Combined with our new WoP-PBS method, the double blind rotation allows computing multiple S-box calls in the round function of FRAST at the cost of a single S-box call. In this way, FRAST enjoys 2.768 (resp. 10.57) times higher throughput compared to Kreyvium (resp. Elisabeth) for TFHE keystream evaluation in the offline phase of the transciphering framework at the cost of slightly larger communication overload
Single-Query Quantum Hidden Shift Attacks
No full textQuantum attacks using superposition queries are known to break many classically secure modes of operation. While these attacks do not necessarily threaten the security of the modes themselves, since they rely on a strong adversary model, they help us to draw limits on their provable security.Typically these attacks use the structure of the mode (stream cipher, MAC or authenticated encryption scheme) to embed a period-finding problem, which can be solved with a dedicated quantum algorithm. The hidden period can be recovered with a few superposition queries (e.g., O(n) for Simon’s algorithm), leading to state or key-recovery attacks. However, this strategy breaks down if the period changes at each query, e.g., if it depends on a nonce.In this paper, we focus on this case and give dedicated state-recovery attacks on the authenticated encryption schemes Rocca, Rocca-S, Tiaoxin-346 and AEGIS- 128L. These attacks rely on a procedure to find a Boolean hidden shift with a single superposition query, which overcomes the change of nonce at each query. This approach has the drawback of a lower success probability, meaning multiple independent (and parallelizable) runs are needed.We stress that these attacks do not break any security claim of the authors, and do not threaten the schemes if the adversary only makes classical queries
SDitH in Hardware
No full textThis work presents the first hardware realisation of the Syndrome-Decodingin-the-Head (SDitH) signature scheme, which is a candidate in the NIST PQC process for standardising post-quantum secure digital signature schemes. SDitH’s hardness is based on conservative code-based assumptions, and it uses the Multi-Party-Computation-in-the-Head (MPCitH) construction. This is the first hardware design of a code-based signature scheme based on traditional decoding problems and only the second for MPCitH constructions, after Picnic. This work presents optimised designs to achieve the best area efficiency, which we evaluate using the Time-Area Product (TAP) metric. This work also proposes a novel hardware architecture by dividing the signature generation algorithm into two phases, namely offline and online phases for optimising the overall clock cycle count. The hardware designs for key generation, signature generation, and signature verification are parameterised for all SDitH parameters, including the NIST security levels, both syndrome decoding base fields (GF256 and GF251), and thus conforms to the SDitH specifications. The hardware design further supports secret share splitting, and the hypercube optimisation which can be applied in this and multiple other NIST PQC candidates. The results of this work result in a hardware design with a drastic reducing in clock cycles compared to the optimised AVX2 software implementation, in the range of 2-4x for most operations. Our key generation outperforms software drastically, giving a 11-17x reduction in runtime, despite the significantly faster clock speed. On Artix 7 FPGAs we can perform key generation in 55.1 Kcycles, signature generation in 6.7 Mcycles, and signature verification in 8.6 Mcycles for NIST L1 parameters, which increase for GF251, and for L3 and L5 parameters