Fábio Borges

EPPP4SMS: Efficient Privacy-Preserving Protocol for Smart Metering Systems and Its Simulation Using Real-World Data

The main contribution of this paper is the construction of the efficient privacy-preserving protocol for smart metering systems (EPPP4SMS), which brings together features of the best privacy-preserving protocols in the literature for smart grids. In addition, EPPP4SMS is faster on the meter side-and in the whole round (encryption, aggregation, and decryption)-than other protocols based on homomorphic encryption and it is still scalable. Moreover, EPPP4SMS enables energy suppliers and customers to verify the billing information and measurements without leaking private information. Since the energy supplier knows the amount of generated electricity and its flow throughout electrical substations, the energy supplier can use this verification to detect energy loss and fraud. Different from verification based on digital signature, our verification enables new features; for example, smart meters and their energy supplier can compute the verification without storing the respective encrypted measurements. Furthermore, EPPP4SMS may be suitable to many other scenarios that need aggregation of time-series data keeping privacy protected, including electronic voting, reputation systems, and sensor networks. In this paper, we present theoretical results of EPPP4SMS and their validation by implementation of algorithms and simulation using real-world measurement data.

Parallel modular exponentiation using load balancing without precomputation

The modular exponentiation operation of the current algorithms for asymmetric cryptography is the most expensive part in terms of computational cost. The RSA algorithm, for example, uses the modular exponentiation algorithm in encryption and decryption procedure. Thus, the overall performance of those asymmetric cryptosystems depends heavily on the performance of the specific algorithm used for modular exponentiation. This work proposes new parallel algorithms to perform this arithmetical operation and determines the optimal number of processors that yields the greatest speedup. The optimal number is obtained by balancing the processing load evenly among the processors. Practical implementations are also performed to evaluate the theoretical proposals.

Analysis of privacy-enhancing protocols based on anonymity networks

In this paper, we analyze privacy-enhancing protocols for Smart Grids that are based on anonymity networks. The underlying idea behind such protocols is attributing two distinct partial identities for each consumer. One is used to send real-time information about the power consumption, and the other for transmitting the billing information. Such protocols provide sender-anonymity for the real-time information, while consolidated data is sent for billing. In this work, the privacy properties of such protocols are analyzed, and their computational efficiency is evaluated and compared using simulation to other solutions based on homomorphic encryption.

Efficient, verifiable, secure, and privacy-friendly computations for the smart grid

In this paper, we present a privacy-preserving protocol between an energy provider and smart meters. Many details about the life of customers can be inferred from fine-grained information on their energy consumption. Different from other state-of-the-art protocols, the presented protocol addresses this issue as well as the integrity of electricity bills. Therefore, our protocol provides secure aggregation of measured consumption per round of measurement and verifiable billing after any period. Aggregation of measured consumption ensures that energy suppliers know the consolidated consumption of their customers. Verifiable billing ensures fairness for customers and their energy supplier. We adapt a homomorphic encryption scheme based on elliptic curve cryptography to efficiently protect the data series of measurements that are collected by smart meters. Moreover, energy suppliers can detect and locate energy loss or fraud in the power grid while retaining the privacy of all consumers.

Parallel algorithms for modular multi-exponentiation

Modular exponentiation is a time-consuming operation widely used in cryptography. Modular multi-exponentiation, a generalization of modular exponentiation also used in cryptography, deserves further analysis from the algorithmic point of view. The parallelization of modular multi-exponentiation can be obtained by generalizing methods used to parallelize modular exponentiation. In this paper, we present a new parallelization method for the modular multi-exponentiation operation with two optimizations. The first one searches for the fastest solution without taking into account the number of processors. The second one balances the load among the processors and finds the smallest number of processors that achieves the fastest solution. In detail, our algorithms compute the product of i modular exponentiations. They split up each exponent in j blocks and start j threads. Each thread processes together i blocks from different exponents. Thus, each block of an exponent is processed in a different thread, but the blocks of different exponents are processed together in the same thread. Using addition chains, we show the minimum number of threads with load balance and optimal running time. Therefore, the algorithms are optimized to run with the minimum time and the minimum number of processors.

An Efficient One-Bit Model for Differential Fault Analysis on Simon Family

In this paper, we describe a family of symmetric cryptographic algorithms and present its cryptanalysis. Specifically, we use differential fault analysis to show a fault attack threat to the block cipher family named Simon. In addition, we present the improvement of a fault attack based on a differential attack method. Moreover, we are the first to to extract the entire secret key using only one round. This property is important because an attacker has to control the hardware to inject faults. However, if the attacker has control of only few hardware components and they compute only one round, previous attacks are not able to recover the entire key. With this side-channel analysis, an attacker can inject faults in one round of Simon with block of 96 or 128 bits to recover therespective entire key of 96 or 128 bits without using SAT solver neither computing Grobner bases. The key can be recoveredusing only differential fault analysis.

Optimized access control enforcement over encrypted content in information-centric networks

The Information-centric Network (ICN) paradigm is an important initiative toward an Internet architecture more suitable for content distribution. The change it imposes by naming, routing, and forwarding content directly on the network layer empowers the architecture with several interesting characteristics, such as in-network caching. As contents are meaningful for different users, they can be opportunistically cached and easily accessed by them, which improves content delivery and user experience. However, the fact that users can retrieve content through caches without interacting with the content provider raises security concerns regarding unauthorized access and the enforcement of access control policies. In this context, we propose an access control solution for ICN by adapting and optimizing a proxy re-encryption scheme, reducing up to 33% the processing time. The proposed solution is perfectly aligned with ICN demands, simultaneously ensuring content protection against unauthorized access of contents retrieved from unrestricted in-network caches as well as access control policies enforcement for legitimate users.

Preserving privacy in a smart grid scenario using quantum mechanics

Studies on smart grid and quantum mechanics have potential to yield several benefits to society, with the former resulting in economic and environmental benefits and the latter providing perfect security and privacy at affordable costs. Recently, security and privacy have become important issues in electrical power grids. In this paper, we describe two quantum privacy-enhancing protocols: one of them requires that the parties initially share a certain amount of quantum entangled states, while the other uses only quantum key distribution methods without sharing quantum entangled states. The two proposed protocols are resistant to attacks from quantum computers. This paper also describes some recent advances of classical and quantum privacy-enhancing technologies. Copyright

Secure and Privacy-Friendly Public Key Generation and Certification

Digital societies increasingly rely on secure communication between parties. Certificate enrollment protocols are used by certificate authorities to issue public key certificates to clients. Key agreement protocols, such as Diffie-Hellman, are used to compute secret keys, using public keys as input, for establishing secure communication channels. Whenever the keys are generated by clients, the bootstrap process requires either (a) an out-of-band verification for certification of keys when those are generated by the clients themselves, or (b) a trusted server to generate both the public and secret parameters. This paper presents a novel constrained key agreement protocol, built upon a constrained Diffie-Hellman, which is used to generate a secure public-private key pair, and to set up a certification environment without disclosing the private keys. In this way, the servers can guarantee that the generated key parameters are safe, and the clients do not disclose any secret information to the servers.

Assessing the impact of cryptographic access control solutions on multimedia delivery in information-centric networks

Information-centric Networks (ICN) aims to improve content delivery by promoting the content as the protagonist of the network layer. By naming, routing, and forwarding named content directly on the network layer, ICN allows the same content to satisfy requests from different users, enabling innetwork caches to place contents strategically near the interested users. This characteristic is especially interesting for multimedia content distribution, since it represents a better quality of experience for users due to low round-trip time, bandwidth use, and load on content providers. However, caching protected multimedia content on uncontrolled third party devices may impair access control policies enforcement by the content providers. Many encryption-based access control solutions have been proposed for ICN, applying different cryptographic strategies leading to distinct features which may not be appropriate for multimedia content protection. In this paper, we simulate, evaluate, and discuss the individual characteristics of three encryption-based access control solutions in light of multimedia distribution in ICN. We show that leveraging cache efficiency, computational load to encrypt and decrypt content, and user revocation are the biggest challenges for the enforcement of access control policies on ICN.