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Constructive Side-Channel Analysis and Secure Design

6th International Workshop, COSADE 2015, Berlin, Germany, April 13-14, 2015. Revised Selected Papers

herausgegeben von: Stefan Mangard, Axel Y. Poschmann

Verlag: Springer International Publishing

Buchreihe : Lecture Notes in Computer Science

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik" , Springer Professional "Wirtschaft"

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Über dieses Buch

This book constitutes the thoroughly refereed post-conference proceedings of the 6th International Workshop, COSADE 2015, held in Berlin, Germany, in April 2015. The 17 revised full papers presented were carefully selected from 48 submissions. the focus of this workshop was on following topics: side-channel attacks, FPGA countermeasures, timing attacks and countermeasures, fault attacks, countermeasures, and Hands-on Side-channel analysis.

Inhaltsverzeichnis

Frontmatter

Side-Channel Attacks

Frontmatter

Improving Non-profiled Attacks on Exponentiations Based on Clustering and Extracting Leakage from Multi-channel High-Resolution EM Measurements

Abstract

The success probability of side-channel attacks depends on the used measurement techniques as well as the algorithmic processing to exploit available leakage. This is particularly critical in case of asymmetric cryptography, where attackers are only allowed single side-channel observations because secrets are either ephemeral or blinded by countermeasures. We focus on non-profiled attacks which require less attacker privileges and cannot be prevented easily. We significantly improve the algorithmic processing in non-profiled attacks based on clustering against exponentiation-based implementations compared to previous contributions. This improvement is mainly due to PCA and a strategy to select few mid-ranked components where exploitable, low-variance leakage is concentrated. As a result from a practical experiment using single-channel high-resolution magnetic field measurements, we report a significant improvement in the number of successful attacks. Further, we present the first practical results from using three such channels simultaneously. The combination of three channels leads to further improved results over the best individual channel when applying a profiled template attack. The clustering-based algorithmic approach for the non-profiled attack, however, does not show improvements from the combination.

Robert Specht, Johann Heyszl, Martin Kleinsteuber, Georg Sigl

Template Attacks vs. Machine Learning Revisited (and the Curse of Dimensionality in Side-Channel Analysis)

Abstract

Template attacks and machine learning are two popular approaches to profiled side-channel analysis. In this paper, we aim to contribute to the understanding of their respective strengths and weaknesses, with a particular focus on their curse of dimensionality. For this purpose, we take advantage of a well-controlled simulated experimental setting in order to put forward two important intuitions. First and from a theoretical point of view, the data complexity of template attacks is not sensitive to the dimension increase in side-channel traces given that their profiling is perfect. Second and from a practical point of view, concrete attacks are always affected by (estimation and assumption) errors during profiling. As these errors increase, machine learning gains interest compared to template attacks, especially when based on random forests.

Liran Lerman, Romain Poussier, Gianluca Bontempi, Olivier Markowitch, François-Xavier Standaert

Efficient Selection of Time Samples for Higher-Order DPA with Projection Pursuits

Abstract

The selection of points-of-interest in leakage traces is a frequently neglected problem in the side-channel literature. However, it can become the bottleneck of practical adversaries/evaluators as the size of the measurement traces increases, especially in the challenging context of masked implementations, where only a combination of multiple shares reveals information in higher-order statistical moments. In this paper, we describe new (black box) tools for efficiently dealing with this problem. The proposed techniques exploit projection pursuits and specialized local search algorithms, work with minimum memory requirements and practical time complexity. We validate them with two case-studies of unprotected and first-order masked implementations in an 8-bit device, the latter one being hard to analyze with previously known methods.

François Durvaux, François-Xavier Standaert, Nicolas Veyrat-Charvillon, Jean-Baptiste Mairy, Yves Deville

Exploring the Resilience of Some Lightweight Ciphers Against Profiled Single Trace Attacks

Abstract

This paper compares attack outcomes w.r.t. profiled single trace attacks of four different lightweight ciphers in order to investigate which of their properties, if any, contribute to attack success. We show that mainly the diffusion properties of both the round function and the key schedule play a role. In particular, the more (reasonably statistically independent) intermediate values are produced in a target implementation, the better attacks succeed. A crucial aspect for lightweight ciphers is hence the key schedule which is often designed to be particularly light. This design choice implies that information from all round keys can be easily combined which results in attacks that succeed with ease.

Valentina Banciu, Elisabeth Oswald, Carolyn Whitnall

Two Operands of Multipliers in Side-Channel Attack

Abstract

The single-shot collision attack on RSA proposed by Hanley et al. is studied focusing on the difference between two operands of multipliers. There are two consequences. Firstly, designing order of operands can be a cost-effective countermeasure.We show a concrete example in which operand order determines success and failure of the attack. Secondly, countermeasures can be ineffective if the asymmetric leakage is considered. In addition to the main results, the attack by Hanley et al. is extended using the signal-processing technique of the big mac attack. An experimental result to successfully analyze an FPGA implementation of RSA with the multiply-always method is also presented.

Takeshi Sugawara, Daisuke Suzuki, Minoru Saeki

FPGA Countermeasures

Frontmatter

Evaluating the Duplication of Dual-Rail Precharge Logics on FPGAs

Abstract

Power-equalization schemes for digital circuits aim to harden cryptographic designs against power analysis attacks. With respect to dual-rail logics most of these schemes have originally been designed for ASIC platforms, but much efforts have been spent to map them to FPGAs as well. A particular challenge is here to apply those schemes to the predefined logic structures of FPGAs (i.e., slices, LUTs, FFs, and routing switch boxes) for which special tools are required. Due to the absence of such routing tools Yu and Schaumont presented the idea of duplicating (i.e., dualizing) a fully-placed-and-routed dual-rail precharge circuit with equivalent routing structures on an FPGA. They adopted such architecture from WDDL providing the Double WDDL (DWDDL) scheme.

In this work we show that this general technique – regardless of the underlying dual-rail logic – is incapable to properly prevent side-channel leakages. Besides theoretical investigations on this issue we present practical evaluations on a Spartan-6 FPGA to demonstrate the flaws in such an approach. In detail, we consider an AES-128 encryption module realized by three dual-rail precharge logic styles as a case study and show that none of those schemes can provide the desired level of protection.

Alexander Wild, Amir Moradi, Tim Güneysu

Side-Channel Protection by Randomizing Look-Up Tables on Reconfigurable Hardware

Pitfalls of Memory Primitives

Abstract

Block Memory Content Scrambling (BMS), presented at CHES 2011, enables an effective way of first-order side-channel protection for cryptographic primitives at the cost of a significant reconfiguration time for the mask update. In this work we analyze alternative ways to implement dynamic first-order masking of AES with randomized look-up tables that can reduce this mask update time. The memory primitives we consider in this work include three distributed RAM components (RAM32M, RAM64M, and RAM256X1S) and one BRAM primitive (RAMB8BWER). We provide a detailed study of the area and time overheads of each implementation technique with respect to the operation (encryption) as well as reconfiguration (mask update) phase. We further compare the achieved security of each technique to prevent first-order side-channel leakages. Our evaluation is based on one of the most general forms of leakage assessment methodology known as non-specific t-test. Practical SCA evaluations (using a Spartan-6 FPGA platform) demonstrate that solely the BRAM primitive but none of the distributed RAM elements can be used to realize an SCA-protected implementation.

Pascal Sasdrich, Oliver Mischke, Amir Moradi, Tim Güneysu

Timing Attacks and Countermeasures

Frontmatter

A Faster and More Realistic Flush+Reload Attack on AES

Abstract

Cloud’s unrivaled cost effectiveness and on the fly operation versatility is attractive to enterprise and personal users. However, the cloud inherits a dangerous behavior from virtualization systems that poses a serious security risk: resource sharing. This work exploits a shared resource optimization technique called memory deduplication to mount a powerful known-ciphertext only cache side-channel attack on a popular OpenSSL implementation of AES. In contrast to the other cross-VM cache attacks, our attack does not require synchronization with the target server and is fully asynchronous, working in a more realistic scenario with much weaker assumption. Also, our attack succeeds in just 15 seconds working across cores in the cross-VM setting. Our results show that there is strong information leakage through cache in virtualized systems and the memory deduplication should be approached with caution.

Berk Gülmezoğlu, Mehmet Sinan İnci, Gorka Irazoqui, Thomas Eisenbarth, Berk Sunar

Faster Software for Fast Endomorphisms

Abstract

GLV curves (Gallant et al.) have performance advantages over standard elliptic curves, using half the number of point doublings for scalar multiplication. Despite their introduction in 2001, implementations of the GLV method have yet to permeate widespread software libraries. Furthermore, side-channel vulnerabilities, specifically cache-timing attacks, remain unpatched in the OpenSSL code base since the first attack in 2009 (Brumley and Hakala) even still after the most recent attack in 2014 (Benger et al.). This work reports on the integration of the GLV method in OpenSSL for curves from 160 to 256 bits, as well as deploying and evaluating two side-channel defenses. Performance gains are up to 51 %, and with these improvements GLV curves are now the fastest elliptic curves in OpenSSL for these bit sizes.

Billy Bob Brumley

Toward Secure Implementation of McEliece Decryption

Abstract

We analyse the security regarding timing attacks of implementations of the decryption in McEliece PKC with binary Goppa codes. First, we review and extend the existing attacks, both on the messages and on the keys. We show that, until now, no satisfactory countermeasure could erase all the timing leakages in the Extended Euclidean Algorithm (EEA) step. Then, we describe a version of the EEA never used for McEliece so far. It uses a constant number of operations for given public parameters. In particular, the operation flow does not depend on the input of the decryption, and thus closes all previous timing attacks. We end up with what should become a central tool toward a secure implementation of McEliece decryption.

Mariya Georgieva, Frédéric de Portzamparc

Fault Attacks

Frontmatter

Fault Injection with a New Flavor: Memetic Algorithms Make a Difference

Abstract

During recent years we observe an arms race between new creative methods for inserting effective faults and designing new countermeasures against such threats. Yet, even analyses of an unprotected smart card pose a problem for an analyst assuming constraints in time (or consequently, in a feasible number of measurements). In this paper we present a new kind of algorithm capable of finding faults in the black box test scenario - memetic algorithm. This algorithm combines the strengths of the following three algorithms: genetic algorithm, tabu search and local search. Furthermore, the same algorithm can be used if the goal is simply a rapid characterization of the search space. We compare our algorithm with random search and exhaustive search approaches. Experimental results show that our memetic algorithm is substantially more successful in both, locating faults and characterizing search space, than the other known methods. In reaching both goals, our memetic algorithm uses less than 300 measurements.

Stjepan Picek, Lejla Batina, Pieter Buzing, Domagoj Jakobovic

Differential Fault Intensity Analysis on PRESENT and LED Block Ciphers

Abstract

Differential Fault Intensity Analysis (DFIA) is a recently introduced fault analysis technique. This technique is based on the observation that faults are biased and thus are non-uniformly distributed over the cipher state variables. The adversary uses the fault bias as a source of leakage by controlling the intensity of fault injection. DFIA exploits statistical analysis to correlate the secret key to the biased fault behavior. In this work, we show a DFIA attack on two lightweight block ciphers: PRESENT and LED. For each algorithm, our research analyzes the efficiency of DFIA on a round-serial implementation and on a nibble-serial implementation.We show that all algorithms and all implementation variants can be broken with 10 to 36 fault intensity levels, depending on the case. We also analyze the factors that affect the convergence of DFIA. We show that there is a trade-off between the number of required plaintexts, and the resolution of the fault-injection equipment. Thus, an adversary with lower-quality fault-injection equipment may still be as effective as an adversary with high-quality fault-injection equipment, simply by using additional encryptions. This confirms that DFIA is effective against a range of algorithms using a range of fault injection techniques.

Nahid Farhady Ghalaty, Bilgiday Yuce, Patrick Schaumont

A Biased Fault Attack on the Time Redundancy Countermeasure for AES

Abstract

In this paper we propose the first practical fault attack on the time redundancy countermeasure for AES using a biased fault model. We develop a scheme to show the effectiveness of a biased fault model in the analysis of the time redundancy countermeasure. Our attack requires only faulty ciphertexts and does not assume strong adversarial powers. We successfully demonstrate our attack on simulated data and 128-bit time redundant AES implemented on Xilinx Spartan-3A FPGA.

Sikhar Patranabis, Abhishek Chakraborty, Phuong Ha Nguyen, Debdeep Mukhopadhyay

Countermeasures

Frontmatter

Faster Mask Conversion with Lookup Tables

Abstract

Masking is an effective and widely-used countermeasure to thwart Differential Power Analysis (DPA) attacks on symmetric cryptosystems. When a symmetric cipher involves a combination of Boolean and arithmetic operations, it is necessary to convert the masks from one form to the other. There exist algorithms for mask conversion that are secure against first-order attacks, but they can not be generalized to higher orders. At CHES 2014, Coron, Großschädl and Vadnala (CGV) introduced a secure conversion scheme between Boolean and arithmetic masking of any order, but their approach requires \(d=2t+1\) shares to protect against attacks of order t. In the present paper, we improve the algorithms for second-order conversion with the help of lookup tables so that only three shares instead of five are needed, which is the minimal number for second-order resistance. Furthermore, we also improve the first-order secure addition method proposed by Karroumi, Richard and Joye, again with lookup tables. We prove the security of all presented algorithms using well established assumptions and models. Finally, we provide experimental evidence of our improved mask conversion applied to HMAC-SHA-1. Simulation results show that our algorithms improve the execution time by 85 % at the expense of little memory overhead.

Praveen Kumar Vadnala, Johann Großschädl

Towards Evaluating DPA Countermeasures for Keccak K1012ECCAK on a Real ASIC

Abstract

We present Zorro, a taped-out ASIC hosting three distinct authenticated encryption architectures based on the SpongeWrap construction. All designs target resource-constrained environments such as smart cards or embedded devices and therefore, have been protected against DPA attacks while keeping low-area as the most important design goal in mind. Each of the three architectures contains masking and hiding countermeasures. They solely differ with regard to the implemented secret-sharing scheme. While the first design is based on a 3-share threshold implementation (TI), which does not fulfill the uniformity property, the other two make use of the 3-share approach with re-masking and the 4-share approach as proposed by Bilgin et al. Our smallest, provable first-order DPA secure Keccak implementation requires only 14.5 kGE (which is less than half of the size of related work) and contains both front-end and back-end design overheads. Moreover, we present first DPA results of the Zorro ASIC by comparing hiding and masking countermeasures. We were able to recover the cipherkey from a masking-secured TI implementation based on three shares with about 70 000 power traces.

Michael Muehlberghuber, Thomas Korak, Philipp Dunst, Michael Hutter

Hands-on Side-Channel Analysis

Frontmatter

Side-Channel Security Analysis of Ultra-Low-Power FRAM-Based MCUs

Abstract

By shrinking the technology and reducing the energy requirements of integrated circuits, producing ultra-low-power devices has practically become possible. Texas Instruments as a pioneer in developing FRAM-based products announced a couple of different microcontroller (MCU) families based on the low-power and fast Ferroelectric RAM technology. Such MCUs come with embedded cryptographic module(s) as well as the assertion that – due to the underlying ultra-low-power technology – mounting successful side-channel analysis (SCA) attacks has become very difficult. In this work we practically evaluate this claimed hardness by means of state-of-the-art power analysis attacks. The leakage sources and corresponding attacks are presented in order to give an overview on the potential risks of making use of such platforms in security-related applications. In short, we partially confirm the given assertion. Some modules, e.g., the embedded cryptographic accelerator, can still be attacked but with slightly immoderate effort. On the contrary, the other leakage sources are easily exploitable leading to straightforward attacks being able to recover the secrets.

Amir Moradi, Gesine Hinterwälder

Side Channel Attacks on Smartphones and Embedded Devices Using Standard Radio Equipment

Abstract

Side Channel Attacks are a powerful instrument to break cryptographic algorithms by measuring physical quantities during the execution of these algorithms on electronic devices. In this paper, the electromagnetic emanations of smartphones and embedded devices will be used to extract secret keys of public key cryptosystems. This will be done using standard radio equipment in combination with far-field antennas. While such attacks have been shown previously, the details of how to find relevant emanations and the limits of the attack remain largely unknown. Therefore, this paper will present all the required steps to find emanations of devices, implement a side channel attack exploiting ultra high frequency emanations and discuss different test setups. The result is a test setup which enables an attacker to mount a side channel attack for less than 30 Euros.

Gabriel Goller, Georg Sigl

Backmatter

Titel: Constructive Side-Channel Analysis and Secure Design
herausgegeben von: Stefan Mangard
Axel Y. Poschmann
Verlag: Springer International Publishing
Electronic ISBN: 978-3-319-21476-4
Print ISBN: 978-3-319-21475-7
DOI: https://doi.org/10.1007/978-3-319-21476-4