Ruhr-Universität Bochum (RUB): Open Journal Systems
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Entropy extractor based high-throughput post-processings for True Random Number Generators
No full textIn cryptographic systems, true random number generation is essential, as a compromised TRNG could lead to a security catastrophe. The raw random numbers are discrete values that are derived at discrete points in time from a noise source of a TRNG. These values often exhibit statistical defects that require post-processing, also called conditioner, to improve uniformity. The two main types of post-processing are algorithmic post-processing and cryptographic post-processing, both of which have pros and cons in theories and applications. However, another type of postprocessing existing between these two types, named entropy extractor, has often been overlooked by the applied cryptographic community. Therefore, we implement two information-theoretically provable entropy extractors: Toeplitz extractor and Trevisan extractor catering to various performance requirements and applications of high-throughput TRNG post-processing. This paper proposes a combination of matrix chunking and FFT acceleration to boost the performance of the Toeplitz extractor, along with a modified Toeplitz matrix design to decrease the hardware consumption. In addition, we introduce a lightweight single-bit extractor to implement an efficient Trevisan extractor. Both algorithms are devised and verified through FPGA hardware simulations. The enhanced Toeplitz extractor achieves a throughput of 42 Gbps, while the Trevisan extractor attains 1.82 Gbps, representing an 84% and 73% improvement in throughput-to-area ratio over the previous best-performing design for each extractor. The standard statistical test suites, such as NIST SP800-22, NIST SP800-90B, and AIS-31, are adopted to evaluate the effectiveness of the proposed post-processing techniques. Naturally, this approach can only serve as a supplementary measure, as modern standards, such as AIS-31, necessitate formal analysis and stochastic models to account for randomness
BASTION: A Framework for Secure Third-Party IP Integration in NoC-based SoC Platforms
No full textModern System-on-Chip (SoC) architectures are a complex mix of processors, accelerators, memories, and I/O controllers interconnected by on-chip communication networks. Given the complexity of the computation and the requirements mandated in modern applications, several of these IPs are often outsourced as third-party modules. The integration of third-party modules, however, has been demonstrated to raise severe system-level security concerns – undiscovered vulnerabilities, incorrect firmware configurations, malicious code, and hardware trojans undetected in such IPs can produce leaks of confidential information and compromise the integrity of critical components. These challenges are further intensified when the communication infrastructure lacks robust mechanisms to supervise and monitor the interactions of third-party IPs with the rest of the system. Thus, runtime monitoring and supervising of third-party IPs is a crucial aspect for the system-level security of the entire SoC – the computing modules integrated in the SoC and their communication must behave securely. This paper presents Bastion, an open-source framework designed to support the secure integration of third-party IP modules into SoC architectures based on network-on-chip (NoC) communications, with a focus on providing robust security guarantees for NoC-based open-source hardware platforms. Unlike most previous works, which either focus on design or verification, we address the challenge of securely integrating third-party IPs in NoC-based platforms through a holistic design and verification framework based on three pillars: (i) a high-performance security socket that can be seamlessly integrated into NoC tiles; (ii) secure configuration and management of the security sockets via a Hardware Root of Trust; and (iii) an ad-hoc property-based security verification framework to ensure secure system operation. Bastion is integrated on the popular open-source ESP framework and validated through simulations and FPGA emulation of realistic SoCs. By explicitly targeting open-source platforms and releasing the entire project as open-source, we aim to democratize access to robustly secure application-specific SoC platforms for critical applications and foster further advancements in this domain
Faster amortized bootstrapping using the incomplete NTT for free
No full textAmortized bootstrapping techniques have been proposed for FHEW/TFHE to efficiently refresh multiple ciphertexts simultaneously within a polynomial modulus. Although recent proposals have very efficient asymptotic complexity, reducing the amortized cost essentially to Õ(1) FHE multiplications, the practicality of such algorithms still suffers from substantial overhead and high decryption failure rates (DFR). In this study, we improve upon one of the state-of-the-art amortized bootstrapping algorithms (Guimarães et al., ASIACRYPT 2023) for FHEW/TFHE-like schemes by introducing an alternative algorithmic strategy. Specifically, we combine Guimarães et al.’s strategy based on a two-part NTT with an incomplete Number Theoretic Transform (NTT) algorithm. The resulting construction is such that the multiplication of higher-degree polynomials that would usually create a bottleneck in an incomplete NTT setting actually comes for free. As a result, we demonstrate a 2.12x speedup compared to the algorithm of Guimarães et al. and a 1.12x improvement over the state-of-the-art (sequential) TFHE-rs while achieving a DFR close to 2−32 for 7-bit messages, although the DFR is higher for 8-bit messages. We also explore trade-offs between execution time and DFR, identifying parameter sets that improve the execution time of Guimarães et al. by 1.41x, while simultaneously reducing the DFR by a factor of 2−22 for 8-bit messages
ABE Cubed: Advanced Benchmarking Extensions for ABE Squared
No full textSince attribute-based encryption (ABE) was proposed in 2005, it has established itself as a valuable tool in the enforcement of access control. For practice, it is important that ABE satisfies many desirable properties such as multi-authority and negations support. Nowadays, we can attain these properties simultaneously, but none of these schemes have been implemented. Furthermore, although simpler schemes have been optimized extensively on a structural level, there is still much room for improvement for these more advanced schemes. However, even if we had schemes with such structural improvements, we would not have a way to benchmark and compare them fairly to measure the effect of such improvements. The only framework that aims to achieve this goal, ABE Squared (TCHES ’22), was designed with simpler schemes in mind.In this work, we propose the ABE Cubed framework, which provides advanced benchmarking extensions for ABE Squared. To motivate our framework, we first apply structural improvements to the decentralized ciphertext-policy ABE scheme supporting negations presented by Riepel, Venema and Verma (ACM CCS ’24), which results in five new schemes with the same properties. We use these schemes to uncover and bridge the gaps in the ABE Squared framework. In particular, we observe that advanced schemes depend on more “variables” that affect the schemes’ efficiency in different dimensions. Whereas ABE Squared only considered one dimension (as was sufficient for the schemes considered there), we devise a benchmarking strategy that allows us to analyze the schemes in multiple dimensions. As a result, we obtain a more complete overview on the computational efficiency of the schemes, and ultimately, this allows us to make better-founded choices about which schemes provide the best efficiency trade-offs for practice
Zone of Interest – On Negation and Denial
Get PDFJonathan Frazer’s film Zone of Interest (2023) is a film about the Höß family during the three and a half years in which Rudolf Höß, as camp commander of Auschwitz, was responsible for the cruelty, torture, murders, and destruction of evidence of the crimes committed in the extermination camp. The house and garden where the family lived and cared for were directly adjacent to the camp wall. The visual images in the film remain outside the camp, while the audio images reproduce the screams, the orders, the shots. Viewers will find themselves noticing that they can hear the violence, but their consciousness repeatedly blocks it out and follows the seemingly easier-to-understand narrative. The film thus allows the viewer to imagine how this dissociation of perception is possible, which Rudolf and Hedwig Höß and their four children actively carry out in different ways. According to Freud’s psychoanalysis, denial and repression are processes that take place in the ego. There is an unconscious in the ego, an unconscious that can be understood as an active process of thinking, not repressed, but denied and rejected. With this insight, Zone of Interest is very close to Hannah Arendt’s thesis that what is so disturbing about the cruelty of the Shoah is not sexually motivated sadism, but the process by which the ego succeeds in not thinking, in undermining and blocking its own faculty of judgment. The disturbing nature of this insight, which Arendt gave provocative clarity with her concept of the banality of evil, was rarely accepted by her critics. Arendt was accused of trivializing cruelty and of having fooled herself by Eichmann’s defense strategies. Frazer’s film also faced such criticism. But if denial and repression are conscious processes of excluding what one has seen from self-reference and thus from judgement, what does that mean for our concepts of violence and cruelty
Registre i im/personalització en la representació de les relacions interpersonals: la traducció alemany-català/espanyol de Der Passfälscher
Get PDFThe representation of interpersonal relationships in fiction is a challenge for the author of the film script and for the audiovisual translator due to the difficulty of translating pragmatic values in a very restricted environment. In this sense, the aim of this article is to analyze how interpersonal relationships are depicted in Der Passfälscher (2022) through register and im/personalization, and how these representations are translated into Catalan and Spanish. To this end, the scenes have been counted, selecting those with socially symmetrical interpersonal constellations and examining them from a qualitative and contrastive approach. The analysis of the data reveals differences based on the target language and the social role of the participants in the interaction. While Catalan manages to maintain the characterizations activated in German to a greater extent, Spanish reflects interpersonal relations more distant from the original text.The representation of interpersonal relationships in fiction is a challenge for the author of the film script and for the audiovisual translator due to the difficulty of translating pragmatic values in a very restricted environment. In this sense, the aim of this article is to analyze how interpersonal relationships are depicted in Der Passfälscher (2022) through register and im/personalization, and how these representations are translated into Catalan and Spanish. To this end, the scenes have been counted, selecting those with socially symmetrical interpersonal constellations and examining them from a qualitative and contrastive approach. The analysis of the data reveals differences based on the target language and the social role of the participants in the interaction. While Catalan manages to maintain the characterizations activated in German to a greater extent, Spanish reflects interpersonal relations more distant from the original text
The North Meets the South in the Mediterranean: Pre-Modern Literary, Political, and Military Exchanges Across Medieval Europe as Reflected in Poetic and Narrative Accounts
Get PDFContrary to traditional perceptions, in the late Middle Ages numerous contacts developed between countries north of the Alps, especially the Holy Roman Empire, and the Mediterranean. Economic and political historians have already confirmed the true extent of exchanges; and art historians have added valuable insights as to the many links of communication. To deepen our understanding of this phenomenon, the present paper addresses the evidence of literary history. Fictional or factual narratives do not necessarily provide hard facts but shed relevant light on a broad concept about the foreign worlds (mentality) whereto especially knights and pilgrims were traveling. We can identify numerous poets who talked explicitly about their visits to the Mediterranean or who have their protagonists travel widely both all over Europe and the neighboring countries. With this evidence in hand, we can proceed to reevaluate late medieval culture as having been much more international if not even global than previously assumed. As much as the Alps appeared to be a significant geographical barrier, the Mediterranean hinterlands were certainly an intimate part of this significant contact zone where East and West met
A More Practical Attack Against Yoroi
Get PDFYoroi is a family of space-hard block cipher proposed at TCHES 2021. This cipher contains two parts, a core part and an AES layer to prevent the blackbox adversary. At FSE 2023, Todo and Isobe proposed a code-lifting attack to recover the secret T-box in Yoroi, breaking the security claims of Yoroi. Their work shows that the AES layer is vulnerable in the whitebox model and has no contribution to the security in a hybrid of blackbox and whitebox model. Besides, their attack employs a strong hack model to modify and extract the table entries of the T-box. This hack model is suitable for the environment used by Yoroi while it is difficult to achieve in the practical application.In this paper, we present an attack on Yoroi within a more practical scenario. Compared with the previous attack, our attack is a chosen-plaintext-ciphertext attack in the blackbox phase and assumes that the whitebox attacker has reduced capabilities, as one only needs to extract the AES key without modifying or extracting the table entries. Furthermore, we introduce a family of equivalent representations of Yoroi, using this we can recover an equivalent cipher without any leaked information of table entries. As a result, the complexities of our attack remain almost the same as that of the previous attack
Improved Search of Boomerang Distinguishers for Generalized Feistel and Application to WARP
Get PDFBoomerang and rectangle cryptanalysis are powerful cryptanalytic techniques for security evaluation of block ciphers. Automated search for boomerang distinguishers is an important area of research. In FSE 2023, Hadipour et al. proposed a MILP model of searching boomerang distinguishers for Feistel structure, and applied their model to obtain the best known boomerang distinguishers to date for many generalized Feistel ciphers including WARP. In this paper, we focus on improving Hadipour et al.’s model for generalized Feistel structure and boomerang distinguishers on WARP. We show that a boomerang distinguisher with more active S-boxes may have a higher probability. It is caused by the semi-active S-boxes active only in one of the upper and lower differential trails, which are not considered in Hadipour et al.’s model. We classify the active S-boxes in the middle part Em in more detail, according to the associated tables of DDT, DDT2, FBCT and its variants in the computation formula of boomerang probability for Em. Then, we propose an improved MILP model to search boomerang distinguishers for generalized Feistel structure. Applying our model to WARP, we find better boomerang distinguishers for all rounds than those found by Hadipour et al.’s model. For 15-round boomerang distinguisher on WARP, the probability is improved by a factor of 25.78. For the longest 23-round boomerang distinguisher, the probability is improved by a factor of 24.23, resulting in the best result presented on WARP so far. Exploiting the properties of two local structures and the probabilistic extension technique, we improve the 26-round rectangle attack and give the first 27-round rectangle attack on WARP, which extends the best previous rectangle attack by one round. Note that our findings do not threaten the security of WARP which iterates 41 rounds