Side Channel attacks

Security of embedded systems is the need of the hour. A mathematically secure algorithm runs on a cryptographic chip on these systems, but secret private data can be at risk due to side-channel leakage information. This research focuses on retrieving secret-key information, by performing machine-learning-based analysis on leaked power-consumption signals, from Field Programmable Gate Array (FPGA) implementation of the elliptic-curve algorithm captured from a Kintex-7 FPGA chip while the elliptic-curve cryptography (ECC) algorithm is running on it. This paper formalizes the methodology for preparing an input dataset for further analysis using machine-learning-based techniques to classify the secret-key bits. Research results reveal how pre-processing filters improve the classification accuracy in certain cases, and show how various signal properties can provide accurate secret classification with a smaller feature dataset. The results further show the parameter tuning and the amount of time required for building the machine-learning models.

Cache timing attack is a type of side channel attack where the leaking timing information due to the cache behaviour of a crypto system is used by an attacker to break the system. Advanced Encryption Standard (AES) was considered a secure encryption standard until 2005 when Daniel Bernstein claimed that the software implementation of AES is vulnerable to cache timing attack. Bernstein demonstrated a remote cache timing attack on a software implementation of AES. The original AES implementation can methodically be altered to prevent the cache timing attack by hiding the natural cache-timing pattern during the encryption while preserving its semantics. The alternations while preventing the attack should not make the implementation very slow. In this paper, we report outcomes of our experiments on designing and implementing a number of possible countermeasures.

Bu çalışmada tam disk şifrelemesine (FDE: Full Disk Encryption) sahip olay yeri bilgisayarlarından delil elde etmede kullanılan teorik ve pratik yöntemler araştırılarak, şifreli disklerden adli delil elde etmede karşılaşılabilecek engellerin nasıl aşılabileceği incelenmiş ve uygulamalı olarak örneklendirilmiştir.

Adli bilişim ve olay yeri incelemeleri açısından  ülkelerin mevzuatlarına ve adli bilişim uzmanlarının eğitimlerine göre değişen çeşitli delil elde etme pratikleri uygulanır. Bilgisayar çalışıyorsa ve oturum kilitli değilse ilk yapılması gerekenlerden biri bilgisayarın sürücülerinde bir disk şifreleme yazılımının çalışıp çalışmadığının araştırılmasıdır. Eğer varsa RAM’in kopyası alınarak şifreleme anahtarının elde edilmesi yoluna gidilir. Ancak bundan sonra disk imajı üzerinde bir adli inceleme gerçekleştirilmesi mümkün olabilir. Şifreleme anahtarı olmayan disk imajlarının şifrelerinin çözülmesi, kullanılan şifreleme türüne ve anahtarın uzunluğuna bağlı olarak çoğu zaman imkansız olmaktadır.




Olay yeri bilgisayarlarına ait disklerin TrueCrypt, PGP, BitLocker, eCryptfs ve EFS  gibi disk şifreleme yazılımları ile şifrelenmiş olduğu durumlarda, eğer bilgisayar oturumu kilitli ise, olay yeri inceleyicisinin şifreleme anahtarını elde etmeye yönelik uygulayacağı  olağan senaryo büyük oranda sekteye uğrar.

Ancak böyle durumlara karşı kilitli ve çalışan sistemlerden şifreleme anahtarının elde edilmesi için uygulanabilecek birçok yöntem bulunmaktadır.

Bu çalışmada kilitli oturuma sahip FDE korumalı olay yeri bilgisayarlarından şifreleme anahtarını elde etmeye yönelik çok geniş bir literatür araştırması yapılmış, teorik ve pratik karşılığı olan ve uygulanan bir çok tekniğe yer verilmiş, yeni sayılabilecek bir teknik olan ağ trafiğinden delil elde edilmesi konusu örneklendirilerek gösterilmiştir.

We present a unified framework for advanced implementation attacks that allows for conducting automated side-channel analysis and fault injection targeting all kinds of embedded cryptographic devices including RFIDs. Our proposed low-cost setup consists of modular functional units that can be interchanged, depending on the demands of a concrete attack scenario. We give details of customized modules for the communication with many types of embedded devices and other modules that allow to inject various types of faults. An FPGA-based approach enables very accurate timing and flexible adaption to any extension module. The corresponding data acquisition system for side-channel attacks makes precise power and EM analyses possible. Our setup facilitates the promising combination of active and passive techniques, which is known to render many established security countermeasures ineffective. We introduce several methods for the automatic profiling of cryptographic devices and model their behaviour both with respect to side-channel analysis and fault injection. To demonstrate the capabilities of our framework, we perform the first practical full key-recovery on a cryptographic contactless smartcard employing Triple-DES reported in the literature and inject multiple faults in a widespread microcontroller. We thereby disprove the common belief that highly sophisticated and expensive equipment is required to conduct such attacks. Rather, we illustrate a cost-effective setup that can be tailored to any desired type of security evaluation or penetration test.

The McEliece and the Niederreiter public key cryptosystems (PKC) are supposed secure in a post quantum world (4) because there is no ecient quantum algorithm for the underlying problems upon which these cryptosystems are built. The CFS, Stern and KKS signature schemes are post-quantum secure because they are based on hard problems of coding theory. The purpose of this article is to describe what kind of attacks have been proposed against code-based constructions and what is missing.

This paper explores the resistance of MOS Current Mode Logic (MCML) against attacks based on the observation of the power consumption. Circuits implemented in MCML, in fact, have unique characteristics both in terms of power consumption and the dependency of the power profile from the input signal pattern. Therefore, MCML is suitable to protect cryptographic hardware from Differential Power Analysis and similar side-channel attacks. In order to demonstrate the effectiveness of different logic styles against power analysis attacks, two full cores implementing the AES algorithm were realized and implemented with CMOS and MCML technology, and a set of different types of attack was performed using power traces derived from SPICE-level simulations. Although all keys were discovered for CMOS, MCML traces did not presents characteristic that can lead to a successful attack.

Cloud computing offers both services that provide resources over the Internet and economic benefits for using these resources. As Cloud services turn out to be more common place, recent works have revealed vulnerabilities connected to cloud systems. Cloud Computing presents an added level of risk because essential services are often outsourced to a third party, which makes it harder to maintain data security and privacy, support data and service availability, and demonstrate compliance. In particular, cloud paradigm advances a danger of information leakage over virtual machine through side-channels. Not at all like conventional computing, the cloud infrastructure supporting a Cloud situation permits commonly doubting customer's concurrent access to the underlying hardware, which leads to a side-channel assault. The target of this paper is to explore potential security issues related to side channel attacks and proposed an Encryption concept against side channel attacks. The proposed work introduces the Data Encryption with Optimized Efficient Elliptic Curve Public Key Encryption (EECPKE).

There has been a lot of interest in recent years in the problems faced by cryptosystems due to side channel attacks. Algorithms for elliptic curve point scalar multiplication such as the double and add method are prone to such attacks. By making use of special addition chains, it is possible to implement a Simple Power Analysis(SPA) resistant cryptosystem. In this

Over the past few years, much research attention has been afforded to the application of remote patient monitoring using embedded mobile devices. However, relatively little research has been done to investigate the security aspects of such scenarios. The present work describes the implementation of a cryptographic algorithm based on elliptic curves on an embedded mobile device useful for healthcare purposes. A personal digital assistant (PDA) has been chosen to be the hardware platform for the implementation as it is particularly suitable for remote patient monitoring applications. The motivation for this paper was to formulate a secure protocol which comprises of signature, encryption and authentication (SEA) as a combined ingredient of secure remote patient monitoring application using mobile devices. This needed to be easy to use and computationally efficient in order to be acceptable to both clinicians and patients and the results indicate a positive outcome.

We study the design of cryptographic primitives resistant to a large class of side-channel attacks, called “memory attacks”, where an attacker can repeatedly and adaptively learn information about the secret key, subject only to the constraint that the overall amount of such information is bounded by some parameter ℓ. Although the study of such primitives was initiated only recently by Akavia et al. [2], subsequent work already produced many such “leakage-resilient” primitives [48,4,42], including signature, encryption, identification (ID) and authenticated key agreement (AKA) schemes. Unfortunately, every existing scheme, — for any of the four fundamental primitives above, — fails to satisfy at least one of the following desirable properties: Efficiency. While the construction may be generic, it should have some efficient instantiations, based on standard cryptographic assumptions, and without relying on random oracles. Strong Security. The construction should satisfy the strongest possible definition of security (even in the presence of leakage). For example, encryption schemes should be secure against chosen ciphertext attack (CCA), while signatures should be existentially unforgeable. Leakage Flexibility. It should be possible to set the scheme parameters so that the leakage bound ℓ can come arbitrarily close to the secret-key size. In this work we design the first signature, encryption, ID and AKA schemes which overcome these limitations, and satisfy all the properties above. Moreover, all our constructions are generic, in several cases elegantly simplifying and generalizing the prior constructions (which did not have any efficient instantiations). We also introduce several tools of independent interest, such as the abstraction (and constructions) of true-simulation extractable NIZK arguments, and a new deniable DH-based AKA protocol based on any CCA-secure encryption.

Software counter measures against side channel attacks considerably hinder performance of cryptographic algorithms in terms of memory or execution time or both. The challenge is to achieve secure implementation with as little extra cost as possible. In this paper we optimize a counter measure for the AES block cipher consisting in transforming a boolean mask to a multiplicative mask prior to a non-linear Byte Substitution operation (thus, avoiding S-box re-computations for every run or storing multiple S-box tables in RAM), while preserving a boolean mask everywhere else. We demonstrate that it is possible to achieve such transformation for a cost of two additional multiplications in the field. However, due to an inherent vulnerability of multiplicative masking to so-called zero attack, an additional care must be taken to securize its implementation. We describe one possible, although not perfect, approach to such an implementation which combines algebraic techniques and partial re-computation of S-boxes. This adds one more multiplication operation, and either occasional S-box re-computations or extra 528 bytes of memory to the total price of the counter measure.