The Key Authority - Secure Key Management in Hierarchical Public Key Infrastructures

We model a private key`s life cycle as a finite state machine. The states are the key`s phases of life and the transition functions describe tasks to be done with the key. Based on this we define and describe the key authority, a trust center module, which potentiates the easy enforcement of secure management of private keys in hierarchical public key infrastructures. This is done by assembling all trust center tasks concerning the crucial handling of private keys within one centralized module. As this module resides under full control of the trust center`s carrier it can easily be protected by well-known organizational and technical measures.Comment: 5 pages, 2 figure

Outflanking and securely using the PIN/TAN-System

The PIN/TAN-system is an authentication and authorization scheme used in e-business. Like other similar schemes it is successfully attacked by criminals. After shortly classifying the various kinds of attacks we accomplish malicious code attacks on real World Wide Web transaction systems. In doing so we find that it is really easy to outflank these systems. This is even supported by the users' behavior. We give a few simple behavior rules to improve this situation. But their impact is limited. Also the providers support the attacks by having implementation flaws in their installations. Finally we show that the PIN/TAN-system is not suitable for usage in highly secure applications.Comment: 7 pages; 2 figures; IEEE style; final versio

Decorrelating Topology with HMC

The investigation of the decorrelation efficiency of the HMC algorithm with respect to vacuum topology is a prerequisite for trustworthy full QCD simulations, in particular for the computation of topology sensitive quantities. We demonstrate that for mpi/mrho ratios <= 0.69 sufficient tunneling between the topological sectors can be achieved, for two flavours of dynamical Wilson fermions close to the scaling region beta=5.6. Our results are based on time series of length 5000 trajectories.Comment: change of comments: LATTICE98(confine

Speeding up the HMC: QCD with Clover-Improved Wilson Fermions

We apply a recent proposal to speed up the Hybrid-Monte-Carlo simulation of systems with dynamical fermions to two flavor QCD with clover-improvement. For our smallest quark masses we see a speed-up of more than a factor of two compared with the standard algorithm.Comment: 3 pages, lattice2002, algorithms, DESY Report-no correcte

Direct Graphene Growth on Insulator

Fabrication of graphene devices is often hindered by incompatibility between the silicon technology and the methods of graphene growth. Exfoliation from graphite yields excellent films but is good mainly for research. Graphene grown on metal has a technological potential but requires mechanical transfer. Growth by SiC decomposition requires a temperature budget exceeding the technological limits. These issues could be circumvented by growing graphene directly on insulator, implying Van der Waals growth. During growth, the insulator acts as a support defining the growth plane. In the device, it insulates graphene from the Si substrate. We demonstrate planar growth of graphene on mica surface. This was achieved by molecular beam deposition above 600{\deg}C. High resolution Raman scans illustrate the effect of growth parameters and substrate topography on the film perfection. Ab initio calculations suggest a growth model. Data analysis highlights the competition between nucleation at surface steps and flat surface. As a proof of concept, we show the evidence of electric field effect in a transistor with a directly grown channel.Comment: 13 pages, 6 figure

Scanning the Topological Sectors of the QCD Vacuum with Hybrid Monte Carlo

We address a long standing issue and determine the decorrelation efficiency of the Hybrid Monte Carlo algorithm (HMC), for full QCD with Wilson fermions, with respect to vacuum topology. On the basis of five state-of-the art QCD vacuum field ensembles (with 3000 to 5000 trajectories each and m_pi/m_rho-ratios in the regime >0.56, for two sea quark flavours) we are able to establish, for the first time, that HMC provides sufficient tunneling between the different topological sectors of QCD. This will have an important bearing on the prospect to determine, by lattice techniques, the topological susceptibility of the vacuum, and topology sensitive quantities like the spin content of the proton, or the eta' mass.Comment: 5 pages, 4 eps-figure

Nanosecond surface interferometry measurements on designed and commercial polymers

The effect of the ablation mechanism on surface morphology changes during an ablation process was studied by comparing three different polymers: a triazene polymer, a polyimide and poly(methylmethacrylate) (PMMA) with nanosecond surface interferometry. The triazene polymer, for which only indications for a photochemical ablation mechanism had been detected in previous studies, revealed no surface swelling, which could be attributed to a thermal ablation mechanism. For polyimide, a photothermal ablation mechanism is usually used to describe the ablation process at irradiation wavelengths ≥248nm. However, the interferometric measurements do not show any surface swelling, which would be a clear indication for a thermal ablation mechanism. A surface swelling was only detected for PMMA with irradiation at 248nm and fluences below the threshold of permanent surface modification. The detected phase shift, which is proportional to the change of the film thickness and the refractive index, can be explained by the opposite signs of the thermal expansion coefficient and the thermal refractive-index coefficien

An Evaluated Certification Services System for the German National Root CA - Legally Binding and Trustworthy Transactions in E-Business and E-Government

National Root CAs enable legally binding E-Business and E-Government transactions. This is a report about the development, the evaluation and the certification of the new certification services system for the German National Root CA. We illustrate why a new certification services system was necessary, and which requirements to the new system existed. Then we derive the tasks to be done from the mentioned requirements. After that we introduce the initial situation at the beginning of the project. We report about the very process and talk about some unfamiliar situations, special approaches and remarkable experiences. Finally we present the ready IT system and its impact to E-Business and E-Government.Comment: 6 pages; 1 figure; IEEE style; final versio