Circuit-Variant Moving Target Defense for Side-Channel Attacks on Reconfigurable Hardware

With the emergence of side-channel analysis (SCA) attacks, bits of a secret key may be derived by correlating key values with physical properties of cryptographic process execution. Power and Electromagnetic (EM) analysis attacks are based on the principle that current flow within a cryptographic device is key-dependent and therefore, the resulting power consumption and EM emanations during encryption and/or decryption can be correlated to secret key values. These side-channel attacks require several measurements of the target process in order to amplify the signal of interest, filter out noise, and derive the secret key through statistical analysis methods. Differential power and EM analysis attacks rely on correlating actual side-channel measurements to hypothetical models. This research proposes increasing resistance to differential power and EM analysis attacks through structural and spatial randomization of an implementation. By introducing randomly located circuit variants of encryption components, the proposed moving target defense aims to disrupt side-channel collection and correlation needed to successfully implement an attac

Side-channel security of superscalar CPUs: Evaluating the Impact of Micro-architectural Features

Side-channel attacks are performed on increasingly complex targets, starting to threaten superscalar CPUs supporting a complete operating system. The difficulty of both assessing the vulnerability of a device to them, and validating the effectiveness of countermeasures is increasing as a consequence. In this work we prove that assessing the side-channel vulnerability of a software implementation running on a CPU should take into account the microarchitectural features of the CPU itself. We characterize the impact of microarchitectural features and prove the effectiveness of such an approach attacking a dual-core superscalar CPU

Higher-order CIS codes

We introduce {\bf complementary information set codes} of higher-order. A binary linear code of length $tk$ and dimension $k$ is called a complementary information set code of order $t$ ($t$-CIS code for short) if it has $t$ pairwise disjoint information sets. The duals of such codes permit to reduce the cost of masking cryptographic algorithms against side-channel attacks. As in the case of codes for error correction, given the length and the dimension of a $t$-CIS code, we look for the highest possible minimum distance. In this paper, this new class of codes is investigated. The existence of good long CIS codes of order $3$ is derived by a counting argument. General constructions based on cyclic and quasi-cyclic codes and on the building up construction are given. A formula similar to a mass formula is given. A classification of 3-CIS codes of length $\le 12$ is given. Nonlinear codes better than linear codes are derived by taking binary images of $\Z_4$-codes. A general algorithm based on Edmonds' basis packing algorithm from matroid theory is developed with the following property: given a binary linear code of rate $1/t$ it either provides $t$ disjoint information sets or proves that the code is not $t$-CIS. Using this algorithm, all optimal or best known $[tk, k]$ codes where $t=3, 4, \dots, 256$ and $1 \le k \le \lfloor 256/t \rfloor$ are shown to be $t$-CIS for all such $k$ and $t$, except for $t=3$ with $k=44$ and $t=4$ with $k=37$.Comment: 13 pages; 1 figur

Towards Side-Channel Resistant Block Cipher Usage or Can We Encrypt Without Side-Channel Countermeasures?

Based on re-keying techniques by Abdalla, Bellare, and Borst [1,2], we consider two black-box secure block cipher based symmetric encryption schemes, which we prove secure in the physically observable cryptography model. They are proven side-channel secure against a strong type of adversary that can adaptively choose the leakage function as long as the leaked information is bounded. It turns out that our simple construction is side-channel secure against all types of attacks that satisfy some reasonable assumptions. In particular, the security turns out to be negligible in the block cipher’s block size n, for all attacks. We also show that our ideas result in an interesting alternative to the implementation of block ciphers using different logic styles or masking countermeasures

Effects of Architecture on Information Leakage of a Hardware Advanced Encryption Standard Implementation

Side-channel analysis (SCA) is a threat to many modern cryptosystems. Many countermeasures exist, but are costly to implement and still do not provide complete protection against SCA. A plausible alternative is to design the cryptosystem using architectures that are known to leak little information about the cryptosystem\u27s operations. This research uses several common primitive architectures for the Advanced Encryption Standard (AES) and assesses the susceptibility of the full AES system to side-channel attack for various primitive configurations. A combined encryption/decryption core is also evaluated to determine if variation of high-level architectures affects leakage characteristics. These different configurations are evaluated under multiple measurement types and leakage models. The results show that different hardware configurations do impact the amount of information leaked by a device, but none of the tested configurations are able to prevent exploitation

Evaluación de la seguridad de sistemas embebidos ante ataques EMA

Los sistemas embebidos de bajo consumo y alto rendimiento, cuya principal aplicación son los dispositivos portátiles tales como: teléfonos móviles, tabletas, consolas de juego, reproductores de música, lectores de libros etc. han experimentado un tremendo auge en los últimos años. Estos dispositivos, además de contener información confidencial (contraseñas, fotos, números de teléfono…) permiten, en su gran mayoría, realizar operaciones bajo redes inalámbricas poco seguras: como transacciones, envío de datos, acceso a cuentas personales etc. Por tanto, se hace imprescindible el análisis del nivel de seguridad alcanzado por estos dispositivos. Sin embargo, a la espera de futuros desarrollos de la estadística, todavía no existe un marco de evaluación de la seguridad totalmente satisfactorio e internacionalmente reconocido. Así por primera vez en este trabajo se evalúa la seguridad relativa de varios microprocesadores representativos del mercado de aplicaciones embebidas de bajo consumo, comparando su respuesta ante un ataque por canal lateral electromagnético. Los dispositivos seleccionados para su evaluación son: 8051 con arquitectura de 8 bits evolucionada (C8051F303 de Silicon Labs). ARM7TDMI-S de 32 bits (LPC2124 de NXP). Dos ARMCortexM3 de 32 bits nunca antes analizados ante ataques por canal lateral: con diseño de alto rendimiento (LPC1769 de NXP) y bajo consumo (STM32L152 de STMicroelectronics). Para la realización de los experimentos se desarrolla un setup propio de medida, altamente automatizado, robusto ante vibraciones y con una capacidad de muestreo superior a lo publicado hasta ahora en la bibliografía. También se propone una nueva métrica para comparar la respuesta de los dispositivos ante ataques por canal lateral, y que se apoya en la correlación estadística. Uno de los elementos cruciales en un ataque por canal lateral electromagnético es el dispositivo o sonda de medida. Las publicaciones de autores que sugieren la utilización de algún tipo de sonda, no aportan datos concluyentes. Este trabajo compara de forma novedosa la respuesta de tres tipos de sondas: dos fabricadas y comercializadas por Electrometrics EM6995 y Langer MFA-R y una tercera fabricada ad-hoc, y manualmente. Como resultado se concluye que cualquier tipo de sonda es factible de ser usada en un ataque electromagnético, aunque son mejores aquellas de alta precisión como la MFA-R de cabeza milimétrica y preamplificador integrado, que sin embargo requieren una preparación y un setup más elaborado. Como resultado final del estudio, se concluye que los dispositivos actuales ARM Cortex M3, ofrecen una seguridad inherente muy superior a la de otros microprocesadores de diseño menos elaborado, y en consecuencia es recomendable usarlos para aquellas aplicaciones cuyos requisitos de seguridad sean elevados. -------------The low power and high performance embedded systems used in mobile devices like mobile phones, tablet computers, music readers, handheld game consoles, book readers… have achieved a great success in the last years. These devices contain confidence information (keys, photographs, telephone numbers…) and usually let us doing operations over unsafe wireless networks: banking transactions, sending data, accessing to personal accounts etc. In consequence, the analysis of the security level reached by these devices is indispensable. However, there isn’t a satisfactory and internationally recognized methodology to assess security. For first time, this work assesses the relative security of several representative low power embedded microprocessors, comparing their response against Electromagnetic Side Channel Attack. The selected devices for this evaluation are: 8051 with new 8 bits architecture (Silicon Labs C8051F303). ARM7TDMI-S of 32 bits (NXP LPC2124). Two 32 bits ARMCortexM3 never before analysed against Side Channel Attacks: with high performance (NXP LPC1769) and low power specifications (STMicroelectronics STM32L152). A measurement setup has been developed to carry out this study. It’s highly automatized, robustly against vibrations and with a higher sampling rate than rest of setups showed in bibliography. Also, a new metric is proposed. It allows to compare device response against correlation side channel attack using statistical correlation. One of the essential elements of an electromagnetic side channel attack is the near field probe. The authors, whose studies suggest the use of some type of probe, do not include conclusion results. This work compares the response of three probes in a new way: Electrometrics EM6995, Langer MFA-R and ones handmade. It concludes that any type of probe is useful in an electromagnetic attack, although the use of high precision probes is recommended. For example, the MFA-R with tiny head and integrated preamplifier. Nevertheless, it requires more training and a precise setup. This study finds out that the updated devices ARM Cortex M3, have a very high security, higher than traditional ones. Therefore, the use of this type of devices in sensitive applications is advisable