M. van der Veen

Face recognition with renewable and privacy preserving binary templates

This paper considers generating binary feature vectors from biometric face data such that their privacy can be protected using recently introduced helper data systems. We explain how the binary feature vectors can be derived and investigate their statistical properties. Experimental results for a subset of the FERET and Caltech databases show that there is only a slight degradation in classification results when using the binary rather than the real-valued feature vectors. Finally, the scheme to extract the binary vectors is combined with a helper data scheme leading to renewable and privacy preserving facial templates with acceptable classification results provided that the within-class variation is not too large.

A Buyer–Seller Watermarking Protocol Based on Secure Embedding

In a forensic watermarking architecture, a buyer-seller protocol protects the watermark secrets from the buyer and prevents false infringement accusations by the seller. Existing protocols encrypt the watermark and the content with a homomorphic public-key cipher and perform embedding under encryption. When used for multimedia data, these protocols create a large computation and bandwidth overhead. In this correspondence, we show that the same functionality can be achieved efficiently using recently proposed secure watermark embedding algorithms.

Design and application of a towed land‐streamer system for cost‐effective 2-D and pseudo-3-D shallow seismic data acquisition

To reduce the field effort required for 2-D and 3-D shallow seismic surveying, we have developed a towed land‐streamer system. It was constructed with self‐orienting gimbal‐mounted geophones housed in heavy (1 kg) cylindrical casings, sturdy seismic cables with reinforced kevlar sheathing, robust waterproof connectors, and a reinforced rubber sheet that helped prevent cable snagging, maintained geophone alignment, and provided additional hold‐down weight for the geophones. Each cable had takeouts for 12 geophones at 1 m or 2 m intervals. By eliminating the need for manual geophone planting and cable laying, acquisition of 2-D profiles with this system proved to be 50–100% faster with 30–40% fewer personnel than conventional procedures. Costs of the land‐streamer system and total weight to be pulled could be minimized by employing nonuniform receiver configurations. Short receiver intervals (e.g., 1 m) at near offsets were necessary for identifying and mapping shallow (<50 m) reflections, whereas larger re...

Lookup-Table-Based Secure Client-Side Embedding for Spread-Spectrum Watermarks

Today, mass-scale electronic content distribution systems embed forensic tracking watermarks primarily at the distribution server. For limiting the bandwidth usage and server complexity and enhancing scalability, it is preferable to embed the watermark at the client. Embedding in these untrusted clients requires secure embedding methods that do not leak unmarked content or the watermarking secrets. In this work, we propose a secure watermark embedding scheme based on lookup tables for spread-spectrum watermarks, which are robust to noise and can be detected without comparison to the original content. We also develop fast detection mechanisms that make the watermark detection feasible for tracking systems with a large number of clients. Our fast detection algorithm improves detection speed of existing methods by six orders of magnitude in a typical system with millions of clients.

3D Face: biometric template protection for 3d face recognition

In this paper we apply template protection to an authentication system based on 3D face data in order to protect the privacy of its users. We use the template protection system based on the helper data system (HDS). The experimental results performed on the FRGC v2.0 database demonstrate that the performance of the protected system is of the same order as the performance of the unprotected system. The protected system has a performance of a FAR ≈ 0.19% and a FRR ≈ 16% with a security level of 35 bits.

Secure Embedding of Spread Spectrum Watermarks using Look-up-Tables

In an electronic content distribution system, it is preferable to embed forensic tracking watermarks at the client-side to limit bandwidth usage and server complexity. Embedding in these untrusted clients, however, requires secure embedding methods that do not leak unmarked contents or the watermarking secrets. In this work, we propose a look-up-table (LUT) based cipher, similar to Andersens Chameleon cipher, for securely embedding spread-spectrum watermarks, which are noise robust and detectable without the original content. We also develop fast detection mechanisms that make the watermark detection feasible for tracking systems with large number of clients. Our fast detection algorithm improves detection speed six orders of magnitude in a typical system.

On the current mechanism in reverse‐biased amorphous‐silicon Schottky contacts. II. Reverse‐bias current mechanism

The physical mechanisms that determine the current transport in reverse‐biased Schottky diodes on undoped ‘‘device‐grade’’ hydrogenated amorphous silicon (a‐Si:H) are elucidated. The current‐voltage (J‐V) curves for several Schottky diodes up to reverse‐biases of 40 V have been measured at temperatures between 40 and 180 °C. The reverse currents generally increase approximately exponentially with reverse bias. The decrease of the apparent barrier height as obtained from internal photoemission experiments is in good agreement with the decrease of the thermal activation energy with reverse bias. Extra information on the current transport mechanism can be obtained from the bias dependence of the prefactor in the Arrhenius plot. A theoretical model is presented which gives a semiquantitative fit to all the features observed in the experimental data. The model involves quantum‐mechanical tunnelling of a thermal distribution of carriers through an image‐force lowered triangular potential shape. At low reverse b...

On the current mechanism in reverse-biased amorphous-silicon Schottky contacts. I. Zero bias barrier heights and current transport mechanism

A study of the zero‐bias barrier heights of hydrogenated amorphous‐silicon‐based Schottky diodes and the prevailing current transport mechanisms in these structures is made using electrical and electro‐optical techniques. Several series of devices were made using Cr, Mo, W, and Pt as Schottky metals. The current‐voltage characteristics of the devices were obtained with their temperature dependence. The barrier heights were determined independently using internal photoemission experiments at three temperatures between 270 and 380 K. In devices where the Schottky barrier is deposited on top of the semiconductor material, the saturation current density is found to be most likely determined by combined drift and diffusion of the carriers. In devices where the Schottky barrier is formed at the bottom of the diode, the transport mechanism tends towards thermionic (field) emission, but only slight effects of the prevailing transport mechanism on the electrical performance of these diodes were observed. Also, in ...

Robust and Secure Biometrics: Some Application Examples

In the past years there has been much theoretical interest in secure extraction of robust strings from noisy measurements. In particular this technique allows extracting robust cryptographic keys from noisy biometric data. This paper starts with an overview of the ideas behind robust and secure string extraction in terms of information reconciliation, privacy amplification and helper data. The main part of the paper gives three application examples explaining how these techniques are used to enhance the convenience and security of devices (e.g. tokens) while preserving also the privacy of the user because neither biometric information nor secret cryptographic keys need to be stored on applications. We discuss a server access token, a 3-way check for a biometric ePassport and a password vault.

Watermarking for Content Aware Intelligent Toys

Digital watermarking establishes a reliable side- channel within audio-visual content. In this work, we use this channel to enable content-aware toys, which react to watermarks present in the content In particular, we discuss how the specific requirements of this application, such as accurate action timing and low-cost detectors, are satisfied with a series of algorithmic choices.