Dominik Engel

A survey on JPEG2000 encryption

Image and video encryption has become a widely discussed topic; especially for the fully featured JPEG2000 compression standard numerous approaches have been proposed. A comprehensive survey of state-of-the-art JPEG2000 encryption is given. JPEG2000 encryption schemes are assessed in terms of security, runtime and compression performance and their suitability for a wide range of application scenarios.

Influence of Data Granularity on Smart Meter Privacy

Through smart metering in the smart grid end-user domain, load profiles are measured per household. Personal data can be inferred from these load profiles by using nonintrusive appliance load monitoring methods, which has led to privacy concerns. Privacy is expected to increase with longer intervals between measurements of load curves. This paper studies the impact of data granularity on edge detection methods, which are the common first step in nonintrusive load monitoring algorithms. It is shown that when the time interval exceeds half the on-time of an appliance, the appliance use detection rate declines. Through a one-versus-rest classification modeling, the ability to detect an appliances use is evaluated through F-scores. Representing these F-scores visually through a heatmap yields an easily understandable way of presenting potential privacy implications in smart metering to the end-user or other decision makers.

Towards a Model-Driven-Architecture Process for Smart Grid Projects

The complexity in electrical power systems is continuously increasing due to its advancing distribution. This affects the topology of the grid infrastructure as well as the IT-infrastructure, leading to various heterogeneous systems, data models, protocols, and interfaces. This in turn raises the need for appropriate processes and tools that facilitate the management of the systems architecture on different levels and from different stakeholders’ view points. In order to achieve this goal, a common understanding of architecture elements and means of classification shall be gained. The Smart Grid Architecture Model (SGAM) proposed in context of the European standardization mandate M/490 provides a promising basis for domainspecific architecture models. The idea of following a Model-Driven-Architecture (MDA)-approach to create such models, including requirements specification based on Smart Grid use cases, is detailed in this contribution. The SGAM-Toolbox is introduced as tool-support for the approach and its utility is demonstrated by two real-world case studies.

Wavelet-based load profile representation for smart meter privacy

A significant portion of (potential) end-users at this point in time are wary about possible disadvantages of smart grid technologies. A critical issue raised by end-users in various studies is the lack of trust in the level of privacy. Smart metering is the component in the end-user domain around which the most intense debate on privacy revolves, because load profiles are made available at high resolutions. Non-intrusive load monitoring (NILM) techniques allow the analysis of these load profiles to infer user behaviour, such as sleep-wake cycles. We investigate and compare the utility of different variants of the wavelet transform for creating a multi-resolution representation of load profiles. In combination with selective encryption, this multi-resolution representation allows end-users to grant or deny access to different resolutions on a “need-to-know” basis. Access to the different resolutions is thereby only granted to parties holding the needed keys. The whole datastream can be transmitted over the smart grid communications network. The lifting implementation of the wavelet transform has computationally low demands and can be run in embedded environments, e.g. on ARM-based architectures, in acceptable time. The proposed approach is evaluated based on the provided level of security, computational demands and feasibility in an economic sense.

Resumable Load Data Compression in Smart Grids

We propose a compression approach for load profile data, which addresses practical requirements of smart metering. By providing linear time complexity with respect to the input data size, our compression approach is suitable for low-complexity encoding and decoding for storage and transmission of load profile data in smart grids. Furthermore, it allows for resumability with very low overhead on error-prone transmission lines, which is an important feature not available for standard time series compression schemes. In terms of compression efficiency, our approach outperforms transmission encodings that are currently used for electricity metering by an order of magnitude.

Format-compliant JPEG2000 encryption in JPSEC: security, applicability, and the impact of compression parameters

JPEG2000 encryption has become a widely discussed topic and quite a number of contributions have been made. However, little is known about JPEG2000 compression parameters and their influence on the security and performance of format, compliant encryption schemes. In this work, a thorough analysis of this topic is presented with a focus on format-compliant packet body encryption as sketched in the FCD 15444-8 (JPSEC). A proof for the reversibility of JPSEC format-compliant packet body encryption is given. As format-compliant packet body encryption preserves the JPEG2000 headers, which severely compromises the security, we additionally discuss packet header encryption with a special focus on format compliance and the influence of compression parameters on these schemes.

Secret Wavelet Packet Decompositions for Jpeg 2000 Lightweight Encryption

A lightweight encryption scheme for JPEG 2000 based on the wavelet packet transform is proposed. This scheme significantly reduces the amount of data to be encrypted compared to full encryption and other partial or selective encryption schemes, at the cost of increased computational complexity in the compression pipeline. We investigate the applicability of this approach in two scenarios: for providing full confidentiality and for its utility as a transparent encryption scheme. We evaluate the presented scheme in the context of each scenario with respect to its impact on compression performance, its complexity, the level of security it provides, and its applicability

An Analysis of Lightweight Encryption Schemes for Fingerprint Images

Two lightweight encryption schemes for fingerprint images based on a bit-plane representation of the data are assessed. We demonstrate a low complexity attack against a scheme recently proposed in literature which exploits one of several weaknesses found. A second scheme is evaluated with respect to two fingerprint recognition systems and recommendations for its safe use are given.

Lightweight JPEG2000 Encryption with Anisotropic Wavelet Packets

A lightweight encryption technique for JPEG2000 with optional support for transparent encryption is proposed. Randomized anisotropic wavelet packet bases are used to construct a secret frequency domain, leading to a situation in which only a minimal amount of data needs to be encrypted. Results and calculations are presented to evaluate the suggested approach in terms of compression performance, security, and applicability

Format-compliant jpeg2000 encryption with combined packet header and packet body protection

All proposals for format-compliant encryption schemes for JPEG2000 that have been made to date only encrypt packet body data, but leave packet header data in plaintext. In this paper we show that for providing strict confidentiality, leaving the packet header in plaintext severely compromises the security of these schemes, as discriminative - and for some settings even visual - information can be extracted from the header. We propose a set of format-compliant transformations of the packet header data that confines this information leakage. Furthermore, we discuss to what extent the proposed header protection scheme may be used to increase the performance of partial/selective encryption schemes that, rather than providing full confidentiality, trade off security for a decrease in computational demands.