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Simulation-based verification of EM side-channel attack resilience of embedded cryptographic systems
Electromagnetic (EM) fields emanated due to switching currents in crypto-blocks can be an effective non-invasive channel for extracting secret keys. Accurate design-time simulation tools are needed to predict vulnerabilities and improve resilience of embedded systems to EM side-channel analysis attacks. Modeling such attacks is challenging, however, as it requires a multitude of expensive simulations across multiple circuit abstraction levels together with EM simulations. In this work, a simulation ow is developed to study the differential EM analysis (DEMA) attack on the Advanced Encryption System (AES) block cipher. The proposed ow enables design-time evaluation of realistic DEMA attacks for the first time. The major challenge is accurately computing signals received by a nearby probe at various positions above the chip surface for a large number of AES encryptions. This requires rapidly generating spatial distribution and transient EM radiation of on-chip current waveforms. Commercial CAD tools are used to generate space-time samples of these waveforms and a custom EM simulator to radiate them. The computations are sped up by focusing on information-leaking time windows, performing hybrid gate- and transistor-level simulations, radiating only the currents on top metallization layers, and generating traces for different encryptions in parallel. These methods reduce simulation time to a manageable ~ 20 hrs wall-clock time/attack allowing a previously impossible level of vulnerability analysis. The proposed ow also allows pinpointing critical regions on the chip most susceptible to EM attacks. We demonstrate that exploiting the spatial profile of circuit elements can reveal cryptographic keys with significantly fewer number of traces than DPA , guiding designers to the most critical areas of the layout. This enables targeted deployment of counter-measures to the highest information-leaking design componentsElectrical and Computer Engineerin
SoK: Design Tools for Side-Channel-Aware Implementations
Side-channel attacks that leak sensitive information through a computing
device's interaction with its physical environment have proven to be a severe
threat to devices' security, particularly when adversaries have unfettered
physical access to the device. Traditional approaches for leakage detection
measure the physical properties of the device. Hence, they cannot be used
during the design process and fail to provide root cause analysis. An
alternative approach that is gaining traction is to automate leakage detection
by modeling the device. The demand to understand the scope, benefits, and
limitations of the proposed tools intensifies with the increase in the number
of proposals.
In this SoK, we classify approaches to automated leakage detection based on
the model's source of truth. We classify the existing tools on two main
parameters: whether the model includes measurements from a concrete device and
the abstraction level of the device specification used for constructing the
model. We survey the proposed tools to determine the current knowledge level
across the domain and identify open problems. In particular, we highlight the
absence of evaluation methodologies and metrics that would compare proposals'
effectiveness from across the domain. We believe that our results help
practitioners who want to use automated leakage detection and researchers
interested in advancing the knowledge and improving automated leakage
detection
Key Management in Wireless Sensor Networks, IP-Based Sensor Networks, Content Centric Networks
Cryptographic keys and their management in network communication is considered the main building block of security over which other security primitives are based. These cryptographic keys ensure the privacy, authentication, integrity and non-repudiation of messages. However, the use of these cryptographic keys and their management in dealing with the resource constrained devices (i.e. Sensor nodes) is a challenging task. A number of key management schemes have been introduced by researchers all over the world for such resource constrained networks. For example, light weight PKI and elliptic curve cryptography schemes are computationally expensive for these resource constrained devices. So far the symmetric key approach is considered best for these constrained networks and different variants of it been developed for these networks (i.e. probabilistic key distribution approach). The probabilistic key distribution approach consumes less memory than the standard symmetric key approach but it suffers from the connectivity issues (i.e. the connectivity depends on the common shared keys between the nodes). Most of those schemes were proposed by considering static sensor networks (e.g. Industrial process monitoring, Environmental monitoring, movement detection in military applications, forests etc.). However, the use of these existing key management schemes for mobile wireless sensor networks applications introduces more challenges in terms of network connectivity, energy consumption, memory cost, communication overhead and protection of key materials against some well known attacks. Keeping these challenges in mind, previous research has proposed some key management schemes considering the mobility scenarios in ad hoc networks and wireless sensor networks (e.g. vehicular networks, health monitoring systems).However these schemes consume more resource because of a much higher communication packet exchange during the handover phase for the authentication of joining and leaving nodes than the static networks where there is no extra communication for the handover and authentication. The motivation of this research work is to investigate and propose new algorithms not only to improve the efficiency of these existing authentication and key management schemes in terms of connectivity, memory and security by considering the mobility scenario in wireless sensor networks, but also to develop new algorithms that suit these constrained networks than the existing schemes. First, we choose the existing key pool approach for authentication and key management and improve its network connectivity and resilience against some well known attacks (e.g. node capturing attacks) while reduce the memory cost by storing those key pools in each sensor node. In the proposed solution, we have divided the main key pool into two virtual mutually exclusive key pools. This division and constructing a key from two chosen keys, one from each key pool, helps to reduce the memory cost of each node by assigning fewer keys for the same level of network connectivity as the existing key pool frameworks. Although, the proposed key pool approach increases the network resilience against node compromission attacks because of the smaller number of keys assigned to each node, however it does not completely nullify the effect of the attacks. Hence we proposed an online mutual authentication and key establishment and management scheme for sensor networks that provides almost 100\% network connectivity and also nullifies the effect of node compromission attacks. In the proposed online key generation approach, the secret key is dependent on both communicating parties. Once the two communicating parties authenticate each other, they would successfully establish a secret communication key, otherwise they stop communication and inform the network manager about the intruder detection and activity. The last part of the thesis considers the integration of two different technologies (i.e. wireless sensor networks and IP networks). This is a very interesting and demanding research area because of its numerous applications, such as smart energy, smart city etc.. However the security requirements of these two kind of networks (resource constrained and resourceful) make key management a challenging task. Hence we use an online key generation approach using elliptic curve cryptography which gives the same security level as the standard PKI approach used in IP networks with smaller key length and is suited for the sensor network packet size limitations. It also uses a less computationally expensive approach than PKI and hence makes ECC suitable to be adopted in wireless sensor networks. In the key management scheme for IP based sensor networks, we generate the public private key pair based on ECC for each individual sensor node. However the public key is not only dependent on the node's parameter but also the parameters of the network to which it belongs. This increases the security of the proposed solution and avoids intruders pretending to be authentic members of the network(s) by spreading their own public keys. In the last part of the thesis we consider Content Centric Networking (CCN) which is a new routing architecture for the internet of the future. Building on the observation that today's communications are more oriented towards content retrieval (web, P2P, etc.) than point-to-point communications (VoIP, IM, etc.), CCN proposes a radical revision of the Internet architecture switching from named hosts (TCP/IP protocols) to named data to best match its current usage. In a nutshell, content is addressable, routable, self-sufficient and authenticated, while locations no longer matter. Data is seen and identified directly by a routable name instead of a location (the address of the server). Consequently, data is directly requested at the network level not from its holder, hence there is no need for the DNS). To improve content diffusion, CCN relies on data distribution and duplication, because storage is cheaper than bandwidth: every content - particularly popular one - can be replicated and stored on any CCN node, even untrustworthy. People looking for particular content can securely retrieve it in a P2P-way from the best locations available. So far, there has been little investigation of the security of CCNs and there is no specific key management scheme for that. We propose an authentication and key establishment scheme for CCNs in which the contents are authenticated by the content generating node, using pre-distributed shares of encryption keys. The content requesting node can get those shares from any node in the network, even from malicious and intruder ones, in accordance with a key concept of CCNs. In our work we also provide means to protect the distributed shares from modification by these malicious/intruder nodes. The proposed scheme is again an online key generation approach but including a relation between the content and its encryption key. This dependency prevents the attackers from modifying the packet or the key share
Data analytics for stochastic control and prognostics in cyber-physical systems
In this dissertation, several novel cyber fault diagnosis and prognosis and defense methodologies for cyber-physical systems have been proposed. First, a novel routing scheme for wireless mesh network is proposed. An effective capacity estimation for P2P and E2E path is designed to guarantee the vital transmission safety. This scheme can ensure a high quality of service (QoS) under imperfect network condition, even cyber attacks. Then, the imperfection, uncertainties, and dynamics in the cyberspace are considered both in system model and controller design. A PDF identifier is proposed to capture the time-varying delays and its distribution. With the modification of traditional stochastic optimal control using PDF of delays, the assumption of full knowledge of network imperfection in priori is relaxed. This proposed controller is considered a novel resilience control strategy for cyber fault diagnosis and prognosis. After that, we turn to the development of a general framework for cyber fault diagnosis and prognosis schemes for CPSs wherein the cyberspace performance affect the physical system and vice versa. A novel cyber fault diagnosis scheme is proposed. It is capable of detecting cyber fault by monitoring the probability of delays. Also, the isolation of cyber and physical system fault is achieved with cooperating with the traditional observer based physical system fault detection. Next, a novel cyber fault prognosis scheme, which can detect and estimate cyber fault and its negative effects on system performance ahead of time, is proposed. Moreover, soft and hard cyber faults are isolated depending on whether potential threats on system stability is predicted. Finally, one-class SVM is employed to classify healthy and erroneous delays. Then, another cyber fault prognosis based on OCSVM is proposed --Abstract, page iv
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