Героїзм і трагедія 5-ї гвардійської армії в битві за Дніпро у вересні – жовтні 1943 р.

(uk) Дослідження торкається маловідомої сторінки в історії Другої світової війни – форсування Дніпра частинами 5-ї гвардійської армії північніше Кременчука, де бійці 32-го й 33-го гвардійських корпусів виконували роль удаваного маневру в жовтні 1943 року, в той час як 7-а гвардійська й 37-а армії розширювали оперативний плацдарм на фронті Домоткань – Дереївка.(ru) Исследование посвящено малоизвестной странице в истории Второй мировой войны – форсированию Днепра соединениями 5-й гвардейской армии севернее Кременчуга, где бойцы 32-го и 33-го гвардейских корпусов, выполняли роль отвлекающего маневра в октябре 1943 года, в то время как 7-я гвардейская и 37-я армии расширяли оперативный плацдарм на фронте Домоткань – Дереевка.(en) The research concerns the little-known page in the history of the Second World War – the forcing of the Dnieper Parts 5-th Guards Army north of Kremenchug, where fighters of the 32-th and 33-th Guards corps, served as red herring in October 1943, while the 7-th and 37 army expanded operational foothold in the front Domotkan – Dereyivka

Fast Evaluation of S-boxes with Garbled Circuits

Garbling schemes are vital primitives for privacy-preserving protocols and for secure two-party computation. This paper presents a projective garbling scheme that assigns $2^n$ values to wires in a circuit comprising XOR and unary projection gates. A generalization of FreeXOR allows the XOR of wires with $2^n$ values to be very efficient. We then analyze the performance of our scheme by evaluating substitution-permutation ciphers. Using our proposal, we measure high-speed evaluation of the ciphers with a moderately increased cost in garbling and bandwidth. Theoretical analysis suggests that for evaluating the nine examined ciphers, one can expect a 4- to 70-fold improvement in evaluation performance with, at most, a 4-fold increase in garbling cost and, at most, an 8-fold increase in communication cost compared to state-of-the-art garbling schemes. In an offline/online setting, such as secure function evaluation as a service, the circuit garbling and communication to the evaluator can proceed before the input phase. Thus our scheme offers a fast online phase. Furthermore, we present efficient computation formulas for the S-boxes of TWINE and Midori64 in Boolean circuits. To our knowledge, our formulas give the smallest number of AND gates for the S-boxes of these two ciphers

Arithmetic Circuit Implementations of S-boxes for SKINNY and PHOTON in MPC

Secure multi-party computation (MPC) enables multiple distrusting parties to compute a function while keeping their respective inputs private. In a threshold implementation of a symmetric primitive, e.g., of a block cipher, each party holds a share of the secret key or of the input block. The output block is computed without reconstructing the secret key. This enables the construction of distributed TPMs or transciphering for secure data transmission in/out of the MPC context. This paper investigates implementation approaches for the lightweight primitives SKINNY and PHOTON in arithmetic circuits. For these primitives, we identify arithmetic expressions for the S-box that result in smaller arithmetic circuits compared to the Boolean expressions from the literature. We validate the optimization using a generic actively secure MPC protocol and obtain 18% faster execution time with 49% less communication data for SKINNY-64-128 and 27% to 74% faster execution time with 49% to 81% less data for PHOTON $P_{100}$ and $P_{288}$. Furthermore, we find a new set of parameters for the heuristic method of polynomial decomposition, introduced by Coron, Roy and Vivek, specialized for SKINNY\u27s 8-bit S-box. We reduce the multiplicative depth from 9 to 5

Attacks on Karlsson and Mitrokotsa\u27s Grouping-Proof-Distance-Bounding Protocol

In the recent IEEE communication letter ``Grouping-Proof-Distance-Bounding Protocols: Keep All Your Friends Close by Karlsson and Mitrokotsa, a protocol for grouping-proof distance-bounding (GPDB) is proposed. In this letter, we show that the proof that is generated by the proposed GBDP protocol does not actually prove anything. Furthermore, we provide a construction towards a distance-bounding grouping-proof, however it remains unclear if one can ever truly combine (privacy-preserving) distance-bounding and a grouping-proof

SAKE+: Strengthened Symmetric-Key Authenticated Key Exchange with Perfect Forward Secrecy for IoT

Lightweight authenticated key exchange (AKE) protocols based on symmetric-key cryptography are important in securing the Internet of Things (IoT). However, achieving perfect forward secrecy (PFS) is not trivial for AKE based on symmetric-key cryptography, as opposed to AKE based on public-key cryptography. The most recent proposals that provide PFS are SAKE and SAKE-AM. In this paper, we first take a closer look at these protocols and observe that they have some limitations, specially when deployed in the context of (industrial) IoT. Specifically, we show that if SAKE is used to establish parallel sessions between a server and multiple IoT nodes, then SAKE is susceptible to timeful attack. As for SAKE-AM, we show that an adversary can disrupt the availability by replaying messages from previous protocol sessions. We then propose SAKE+ that mitigates the timeful attack and that allows for concurrent execution of the protocol. Since traceability is a barrier for an AKE scheme in (industrial) IoT applications and SAKE-AM does not provide untraceability property, we improve upon SAKE-AM and propose SAKE+-AM that offers untraceability in addition to mitigating the replay attack. Finally, we prove the security and soundness of our schemes, and verify using a formal verification tool ProVerif

Frictionless Authentication Systems: Emerging Trends, Research Challenges and Opportunities

Authentication and authorization are critical security layers to protect a wide range of online systems, services and content. However, the increased prevalence of wearable and mobile devices, the expectations of a frictionless experience and the diverse user environments will challenge the way users are authenticated. Consumers demand secure and privacy-aware access from any device, whenever and wherever they are, without any obstacles. This paper reviews emerging trends and challenges with frictionless authentication systems and identifies opportunities for further research related to the enrollment of users, the usability of authentication schemes, as well as security and privacy trade-offs of mobile and wearable continuous authentication systems.Comment: published at the 11th International Conference on Emerging Security Information, Systems and Technologies (SECURWARE 2017

Unconditionally Secure Signatures

Digital signatures are one of the most important cryptographic primitives. In this work we construct an information-theoretically secure signature scheme which, unlike prior schemes, enjoys a number of advantageous properties such as short signature length and high generation efficiency, to name two. In particular, we extend symmetric-key message authentication codes (MACs) based on universal hashing to make them transferable, a property absent from traditional MAC schemes. Our main results are summarised as follows. - We construct an unconditionally secure signature scheme which, unlike prior schemes, does not rely on a trusted third party or anonymous channels. In our scheme, a sender shares with each of the remaining protocol participants (or recipients) a set of keys (or hash functions) from a family of universal hash functions. Also, the recipients share with each other a random portion of the keys that they share with the sender. A signature for a message is a vector of tags generated by applying the hash functions to the message. As such, our scheme can be viewed as an extension of MAC schemes, and therefore, the practical implementation of our scheme is straightforward. - We prove information-theoretic security of our scheme against forging, repudiation, and non-transferability. - We compare our schemes with existing both classical (not employing quantum mechanics) and quantum unconditionally secure signature schemes. The comparison shows that our new scheme has a number of unparalleled advantages over the previous schemes. - Finally, although our scheme does not rely on trusted third parties, we discuss this, showing that having a trusted third party makes our scheme even more attractive

Vulnerability of "A novel protocol-authentication algorithm ruling out a man-in-the-middle attack in Quantum Cryptography"

In this paper we review and comment on "A novel protocol-authentication algorithm ruling out a man-in-the-middle attack in quantum cryptography", [M. Peev et al., Int. J. Quant. Inform., 3, 225, (2005)]. In particular, we point out that the proposed primitive is not secure when used in a generic protocol, and needs additional authenticating properties of the surrounding quantum-cryptographic protocol.Comment: 6 page