1,721,126 research outputs found
Constant weight strings in constant time: a building block for code-based post-quantum cryptosystems
Full text linkCode based cryptosystems often need to encode either a message or a random bitstring into one of fixed length and fixed (Hamming) weight. The lack of an efficient and reliable bijective map presents a problem in building constructions around the said cryptosystems to attain security against active attackers. We present an efficiently computable, bijective function which yields the desired mapping. Furthermore, we delineate how the said function can be computed in constant time. We experimentally validate the effectiveness and efficiency of our approach, comparing it against the current state of the art solutions, achieving three to four orders of magnitude improvements in computation time, and validate its constant runtim
Cell type specific gene delivery using chemically modified AAV vectors
Full text linkIn the last years the use of Adeno-Associated Viruses (AAVs) as carriers for gene transfer became increasingly popular for both research and clinical applications. Besides their excellent safety profile, the existence of various AAV serotypes characterized by different proprieties is exploited in the context of gene therapy to target a broad range of diseases. However, currently used techniques to re-direct AAV tropism still present many drawbacks. With this project, we have developed a tool that could enable cell-type specific reprogramming of viral tropism based of post-production chemical modifications of the vectors. By using AAV2 as representative serotype, we patented a method to chemically coupling targeting ligands by exploiting naturally occurring functional groups present on viral capsid. In particular, we have employed different heterobifunctional crosslinker molecules to couple the lectins Wheat Germ Agglutinin (WGA) and Griffonia Simplicifolia Isolectin B4 (IB4), the protein Nerve Growth Factor (NGF) and the Protease-Activated Receptor 1 (PAR1) agonist peptide SFLLRN directly with the amine groups (-NH2) present on lysine residues that compose AAV viral proteins (VPs). After in vitro validation and optimization of modified vectors, their efficiency and acquired specificity were assessed in a mouse model, where we were able to confirm correct re-targeting of viral tropism and acquired accurate cell-type specificity. Moreover, we have explored other possible applications of our tool, including boosting transduction efficiency of different AAV serotypes and conferring particular proprieties such as increased permeability for cellular barriers. Due to its versatility, the technology we have developed could be exploited in different fields of basic and applied research and could have a major impact on gene therapy approaches. Furthermore, being it based on simple click chemistry reactions, it could allow for streamlined modification of different class of viruses, thus offering a valid and more flexible alternative to currently used methods to re-direct viral tropism based on genetic modifications
An Enhanced Dataflow Analysis to Automatically Tailor Side Channel Attack Countermeasures to Software Block Ciphers
Full text linkProtecting software implementations of block ciphers from side channel attacks is a significant concern to realize secure embedded computation platforms. The relevance of the issue calls for the automation of the side channel vulnerability assessment of a block cipher implementation, and the automated application of provably secure defenses. The most recent methodology in the field is an application of a specialized data-flow analysis, performed by means of the LLVM compiler framework, detecting in the AES cipher the portions of the code
amenable to key extraction via side channel analysis. The contribution of this work is an enhancement to the existing data-flow analysis which extending it to tackle any block cipher implemented in software. In particular, the extended strategy takes fully into account the data dependencies present in the key schedule of a block cipher, regardless of its complexity, to obtain consistently sound results. This paper details the analysis strategy and presents new results on the tailored application of power and electro-magnetic emission analysis countermeasures, evaluating the performances on both the ARM Cortex-M and the MIPS ISA. The experimental evaluation reports a case study on two block ciphers: the first designed to achieve a high security margin at a non-negligible computational cost, and a lightweight one. The results show that, when side-channel-protected implementations are considered, the high-security block cipher is indeed more efficient than the lightweight one
Metis: An Integrated Morphing Engine CPU to Protect Against Side Channel Attacks
Full text linkPower consumption and electromagnetic emissions analyses are well established attack avenues for secret values extraction in a large range of embedded devices. Countermeasures against these attacks are approached at different levels, from modified logic styles, to changes in the software implementations. In this work, we propose a microarchitectural modification to a compact RISC-V SoC, the OpenTitan open source silicon root of trust, providing a code morphing countermeasure against power and electromagnetic emissions side channel attacks. Our approach allows the countermeasure to be applied transparently, without the need for any software modification to the cryptographic primitive running on OpenTitan. Our microarchitecture integration of a morphing engine also allows us to provide transparent protection to memory operations. We validate our approach through measurements on an actual FPGA prototype on a Xilinx Artix-7. Our integrated morphing engine increases the FPGA resource consumption by less than 8%, plus the resources required by an RNG of choice, with respect to the original OpenTitan SoC. Our design shows a side channel attack resistance improvement of at least 250× in the Measurements-To-Disclose metric with respect to the unprotected design. We benchmark the performance of our proposed architecture on all the ISO/IEC standard symmetric block ciphers, including, among the other AES, reducing the execution time overhead by 21× to 141× with respect to a continuously morphing software solution
Secure and Efficient Design of Block Cipher Implementations on Microcontrollers
No full textThe vast diffusion of microcontrollers has led to their employment in security sensitive contexts, where the need for trusted implementations of cryptographic algorithms is paramount. These architectures are usually endowed with software and occasionally hardware implementation of ciphers, but in both cases, the price envelope is the first figure to be optimised. The strongest threat to microcontroller security has been proven to be represented by side-channel attacks: power consumption analysis and Electromagnetic (EM) emissions analysis being the prime opportunities to retrieve the secret key embedded in the devices via commonly overlooked information leakage. We propose an efficient solution to the problem of compromising EM emissions from an embedded device, showing which are the design space parameters available to the designer, and how to appropriately tune the security margin with respect to the performances, obtaining an order of magnitude improvement over the state-of-the-art solutions
A comprehensive analysis of constant-time polynomial inversion for post-quantum cryptosystems
Full text linkPost-quantum cryptosystems have currently seen a surge in interest thanks to the current standardization initiative by the U.S.A. National Institute of Standards and Technology (NIST). A common primitive in post-quantum cryptosystems, in particular in code-based ones, is the computation of the inverse of a binary polynomial in a binary polynomial ring. In this work, we analyze, realize in software, and benchmark a broad spectrum of binary polynomial inversion algorithms, targeting operand sizes which are relevant for the current second round candidates in the NIST standardization process. We evaluate advantages and shortcomings of the different inversion algorithms, including their capability to run in constant-time, thus preventing timing side-channel attacks
Exploiting Bit-level Parallelism in GPGPUs: a Case Study on KEELOQ Exhaustive Key Search Attack
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