HyPoRes: An Hybrid Representation System for ECC, Paulo Martins and Leonel Sousa (INESC-ID), Jérémy Marrez and Jean-Claude Bajard (Sorbonne Université)

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Abstract: The Residue Number System (RNS) is a numeral representation enabling for more efficient addition and multiplication implementations. However, due its non-positional nature, modular reductions, required for example by Elliptic Curve (EC) Cryptography (ECC), become costlier. Traditional approaches to RNS modular reduction resort to the Montgomery algorithm, underpinned by large basis extensions. Recently, Hybrid-Positional Residue Number Systems (HPRs) have been proposed, providing a trade-off between the efficiency of RNS and the flexibility of positional number representations. Numbers are represented in a positional representation with the coefficients represented in RNS. By crafting primes of a special form, the complexity of reductions modulo those primes is mitigated, relying on extensions of smaller bases. Due to the need of crafting special primes, this approach is not directly extensible to group operations over currently standardised elliptic curves. In this paper, the Hybrid-Polynomial Residue Number System (HyPoRes) is proposed, enabling for improved modular reductions for any prime. Experimental results show that the modular reduction of HyPoRes, although at most 1.4 times slower than HPR for HPR-crafted primes, is up to 1.4 times faster than a generic RNS approach for primes of ECC standards.

[Preprint] Evaluation of Password Hashing Schemes in Open Source Web Platforms, Ntantogian Christoforos; Maliaros Stefanos; Xenakis Christos (UPRC)

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Abstract: Nowadays, the majority of web platforms in the Internet originate either from CMS to easily deploy websites or by web applications frameworks that allow developers to design and implement web applications. Considering the fact that CMS are intended to be plug and play solutions and their main aim is to allow even non-developers to deploy websites, we argue that the default hashing schemes rarely are modified. Also, recent studies suggest that even developers do not use appropriate hash functions to protect passwords, since they may not have adequate security expertise. Therefore, the default settings of CMS and web applications frameworks play an important role in the security of password storage. This paper evaluates the default hashing schemes of popular CMS and web application frameworks. First, we formulate the cost time of password guessing attacks and next we investigate the default hashing schemes of popular CMS and web applications frameworks. We then apply our framework to perform a comparative analysis of the cost time of password guessing attacks between the various CMS and web application frameworks. Finally, considering that intensive hash functions consume computational resources, we analyze hashing schemes from a different perspective. That is, we investigate if it is feasible and under what conditions to perform slow rate denial of service attacks from concurrent login attempts. Through our study we have derived a set of critical observations. We have discovered that many CMS and web application frameworks use outdated hash functions, arbitrary number of hash iterations, while there is a lack of password policies and salt. Notably, the popular WordPress still uses MD5 with low number of hash iterations. Overall, we believe that the security status of the hashing schemes of CMS and web application frameworks calls for changes to the default settings from an opt-in to an opt-out security policy. More security audits and official library implementations are also required to accelerate the adoption of memory hard functions both by policy makers and the industry..

L-DAA: Lattice-Based Direct Anonymous Attestation, Nada El Kassem and Liqun Chen (Surrey), Jan Camenisch (IBM), Rachid El Bansarkhani (TU Darmstadt), Ali El Kaafarani and Patrick Hough (Oxford)

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Abstract: The Cloud-Edges (CE) framework, wherein small groups of Internet of Things (IoT) devices are serviced by local edge devices, enables a more scalable solution to IoT networks. The trustworthiness of the network may be ensured with Trusted Platform Modules (TPMs). This small hardware chip is capable of measuring and reporting a representation of the state of an IoT device. When connecting to a network, the IoT platform might have its state signed by the TPM in an anonymous way to prove both its genuineness and secure state through the Direct Anonymous Attestation (DAA) protocol. Currently standardised DAA schemes have their security supported on the factoring and discrete logarithm problems. Should a quantum-computer become available in the next few decades, these schemes will be broken. There is therefore a need to start developing a post-quantum DAA protocol. This paper presents a Lattice-based DAA (LDAA) scheme to meet this requirement. The security of this scheme is proved in the Universally Composable (UC) security model under the hardness assumptions of the Ring Inhomogeneous Short Integer Solution (Ring-ISIS) and Ring Learning With Errors (Ring-LWE) problems. Compared to the only other post-quantum DAA scheme available in related art, the storage requirements of the TPM are reduced twofold and the signature sizes 5 times. Moreover, experimental results show that the signing and verification operations are accelerated 1.1 and 2.0 times, respectively.


Implementing RLWE-based Schemes Using an RSA Co-Processor, Martin R. Albrecht, Christian Hanser, Andrea Hoeller, Thomas Pöppelmann, Fernando Virdia and Andreas Wallner

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Abstract: We repurpose existing RSA/ECC co-processors for (ideal) lattice-based cryptography by exploiting the availability of fast long integer multiplication. Such co-processors are deployed in smart cards in passports and identity cards, secured microcontrollers and hardware security modules (HSM). In particular, we demonstrate an implementation of a variant of the Module-LWE-based Kyber Key Encapsulation Mechanism (KEM) that is tailored for optimal performance on a commercially available smart card chip (SLE 78). To benefit from the RSA/ECC co-processor we use Kronecker substitution in combination with schoolbook and Karatsuba polynomial multiplication. Moreover, we speed-up symmetric operations in our Kyber variant using the AES co-processor to implement a PRNG and a SHA-256 co-processor to realise hash functions. This allows us to execute CCA-secure Kyber768 key generation in 79.6 ms, encapsulation in 102.4 ms and decapsulation in 132.7 ms.