International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Pascal Sasdrich

Publications

Year
Venue
Title
2022
TCHES
Generic Hardware Private Circuits - Towards Automated Generation of Composable Secure Gadgets
David Knichel Pascal Sasdrich Amir Moradi
With an increasing number of mobile devices and their high accessibility, protecting the implementation of cryptographic functions in the presence of physical adversaries has become more relevant than ever. Over the last decade, a lion’s share of research in this area has been dedicated to developing countermeasures at an algorithmic level. Here, masking has proven to be a promising approach due to the possibility of formally proving the implementation’s security solely based on its algorithmic description by elegantly modeling the circuit behavior. Theoretically verifying the security of masked circuits becomes more and more challenging with increasing circuit complexity. This motivated the introduction of security notions that enable masking of single gates while still guaranteeing the security when the masked gates are composed. Systematic approaches to generate these masked gates – commonly referred to as gadgets – were restricted to very simple gates like 2-input AND gates. Simply substituting such small gates by a secure gadget usually leads to a large overhead in terms of fresh randomness and additional latency (register stages) being introduced to the design. In this work, we address these problems by presenting a generic framework to construct trivially composable and secure hardware gadgets for arbitrary vectorial Boolean functions, enabling the transformation of much larger sub-circuits into gadgets. In particular, we present a design methodology to generate first-order secure masked gadgets which is well-suited for integration into existing Electronic Design Automation (EDA) tools for automated hardware masking as only the Boolean function expression is required. Furthermore, we practically verify our findings by conducting several case studies and show that our methodology outperforms various other masking schemes in terms of introduced latency or fresh randomness – especially for large circuits.
2022
TCHES
Automated Generation of Masked Hardware
Masking has been recognized as a sound and secure countermeasure for cryptographic implementations, protecting against physical side-channel attacks. Even though many different masking schemes have been presented over time, design and implementation of protected cryptographic Integrated Circuits (ICs) remains a challenging task. More specifically, correct and efficient implementation usually requires manual interactions accompanied by longstanding experience in hardware design and physical security. To this end, design and implementation of masked hardware often proves to be an error-prone task for engineers and practitioners. As a result, our novel tool for automated generation of masked hardware (AGEMA) allows even inexperienced engineers and hardware designers to create secure and efficient masked cryptograhic circuits originating from an unprotected design. More precisely, exploiting the concepts of Probe-Isolating Non-Interference (PINI) for secure composition of masked circuits, our tool provides various processing techniques to transform an unprotected design into a secure one, eventually accelerating and safeguarding the process of masking cryptographic hardware. Ultimately, we evaluate our tool in several case studies, emphasizing different trade-offs for the transformation techniques with respect to common performance metrics, such as latency, area, and randomness.
2021
TCHES
FIVER – Robust Verification of Countermeasures against Fault Injections 📺
Fault Injection Analysis is seen as a powerful attack against implementations of cryptographic algorithms. Over the last two decades, researchers proposed a plethora of countermeasures to secure such implementations. However, the design process and implementation are still error-prone, complex, and manual tasks which require long-standing experience in hardware design and physical security. Moreover, the validation of the claimed security is often only done by empirical testing in a very late stage of the design process. To prevent such empirical testing strategies, approaches based on formal verification are applied instead providing the designer early feedback.In this work, we present a fault verification framework to validate the security of countermeasures against fault-injection attacks designed for ICs. The verification framework works on netlist-level, parses the given digital circuit into a model based on Binary Decision Diagrams, and performs symbolic fault injections. This verification approach constitutes a novel strategy to evaluate protected hardware designs against fault injections offering new opportunities as performing full analyses under a given fault models.Eventually, we apply the proposed verification framework to real-world implementations of well-established countermeasures against fault-injection attacks. Here, we consider protected designs of the lightweight ciphers CRAFT and LED-64 as well as AES. Due to several optimization strategies, our tool is able to perform more than 90 million fault injections in a single-round CRAFT design and evaluate the security in under 50 min while the symbolic simulation approach considers all 2128 primary inputs.
2020
TCHES
Low-Latency Hardware Masking with Application to AES 📺
During the past two decades there has been a great deal of research published on masked hardware implementations of AES and other cryptographic primitives. Unfortunately, many hardware masking techniques can lead to increased latency compared to unprotected circuits for algorithms such as AES, due to the high-degree of nonlinear functions in their designs. In this paper, we present a hardware masking technique which does not increase the latency for such algorithms. It is based on the LUT-based Masked Dual-Rail with Pre-charge Logic (LMDPL) technique presented at CHES 2014. First, we show 1-glitch extended strong noninterference of a nonlinear LMDPL gadget under the 1-glitch extended probing model. We then use this knowledge to design an AES implementation which computes a full AES-128 operation in 10 cycles and a full AES-256 operation in 14 cycles. We perform practical side-channel analysis of our implementation using the Test Vector Leakage Assessment (TVLA) methodology and analyze univariate as well as bivariate t-statistics to demonstrate its DPA resistance level.
2020
TOSC
SKINNY-AEAD and SKINNY-Hash 📺
We present the family of authenticated encryption schemes SKINNY-AEAD and the family of hashing schemes SKINNY-Hash. All of the schemes employ a member of the SKINNY family of tweakable block ciphers, which was presented at CRYPTO 2016, as the underlying primitive. In particular, for authenticated encryption, we show how to instantiate members of SKINNY in the Deoxys-I-like ΘCB3 framework to fulfill the submission requirements of the NIST lightweight cryptography standardization process. For hashing, we use SKINNY to build a function with larger internal state and employ it in a sponge construction. To highlight the extensive amount of third-party analysis that SKINNY obtained since its publication, we briefly survey the existing cryptanalysis results for SKINNY-128-256 and SKINNY-128-384 as of February 2020. In the last part of the paper, we provide a variety of ASIC implementations of our schemes and propose new simple SKINNY-AEAD and SKINNY-Hash variants with a reduced number of rounds while maintaining a very comfortable security margin. https://csrc.nist.gov/Projects/Lightweight-Cryptography
2020
ASIACRYPT
SILVER - Statistical Independence and Leakage Verification 📺
David Knichel Pascal Sasdrich Amir Moradi
Implementing cryptographic functions securely in the presence of physical adversaries is still a challenge although a lion's share of research in the physical security domain has been put in development of countermeasures. Among several protection schemes, masking has absorbed the most attention of research in both academic and industrial communities, due to its theoretical foundation allowing to provide proofs or model the achieved security level. In return, masking schemes are difdicult to implement as the implementation process often is manual, complex, and error-prone. This motivated the need for formal verification tools that allow the designers and engineers to analyze and verify the designs before manufacturing. In this work, we present a new framework to analyze and verify masked implementations against various security notions using different security models as reference. In particular, our framework { which directly processes the resulting gate-level netlist of a hardware synthesis { particularly relies on Reduced Ordered Binary Decision Diagrams (ROBDDs) and the concept of statistical independence of probability distributions. Compared to existing tools, our framework captivates due to its simplicity, accuracy, and functionality while still having a reasonable efficiency for many applications and common use-cases.
2017
CHES
Bit-Sliding: A Generic Technique for Bit-Serial Implementations of SPN-based Primitives
Area minimization is one of the main efficiency criterion for lightweight encryption primitives. While reducing the implementation data path is a natural strategy for achieving this goal, Substitution-Permutation Network (SPN) ciphers are usually hard to implement in a bit-serial way (1-bit data path). More generally, this is hard for any data path smaller than its Sbox size, since many scan flip-flops would be required for storage, which are more area-expensive than regular flip-flops.In this article, we propose the first strategy to obtain extremely small bit-serial ASIC implementations of SPN primitives. Our technique, which we call bit-sliding, is generic and offers many new interesting implementation trade-offs. It manages to minimize the area by reducing the data path to a single bit, while avoiding the use of many scan flip-flops.Following this general architecture, we could obtain the first bit-serial and the smallest implementation of AES-128 to date (1560 GE for encryption only, and 1738 GE for encryption and decryption with IBM 130 nm standard-cell library), greatly improving over the smallest known implementations (about 30% decrease), making AES-128 competitive to many ciphers specifically designed for lightweight cryptography. To exhibit the generality of our strategy, we also applied it to the PRESENT and SKINNY block ciphers, again offering the smallest implementations of these ciphers thus far, reaching an area as low as 1065 GE for a 64-bit block 128-bit key cipher. It is also to be noted that our bit-sliding seems to obtain very good power consumption figures, which makes this implementation strategy a good candidate for passive RFID tags.
2016
CRYPTO
2016
FSE
2015
EPRINT
2015
EPRINT
2015
EPRINT