Implementation Aspects of Anonymous Credential Systems for Mobile Trusted Platforms

Part 1: Research PapersInternational audienceAnonymity and privacy protection are very important issues for Trusted Computing enabled platforms. Protection mechanisms are required in order to hide activities of the trusted platforms when performing cryptography based transactions over the Internet, which would otherwise compromise the platform’s privacy and with it the users’s anonymity. In order to address this problem, the Trusted Computing Group (TCG) has introduced two concepts addressing the question how the anonymity of Trusted Platform Modules (TPMs) and their enclosing platforms can be protected. The most promising of these two concepts is the Direct Anonymous Attestation (DAA) scheme which eliminates the requirement of a remote authority but includes complex mathematical computations. Moreover, DAA requires a comprehensive infrastructure consisting of various components in order to allow anonymous signatures to be used in real-world scenarios. In this paper, we discuss the results of our analysis of an infrastructure for anonymous credential systems which is focused on the Direct Anonymous Attestation (DAA) scheme as specified by the TCG. For the analysis, we especially focus on mobile trusted platforms and their requirements. We discuss our experiences and experimental results when designing and implementing the infrastructure and give suggestions for improvements and propose concepts and models for - from our point of view - missing components

Nitric oxide homeostasis as a target for drug additives to cardioplegia

The vascular endothelium of the coronary arteries has been identified as the important organ that locally regulates coronary perfusion and cardiac function by paracrine secretion of nitric oxide (NO) and vasoactive peptides. NO is constitutively produced in endothelial cells by endothelial nitric oxide synthase (eNOS). NO derived from this enzyme exerts important biological functions including vasodilatation, scavenging of superoxide and inhibition of platelet aggregation. Routine cardiac surgery or cardiologic interventions lead to a serious temporary or persistent disturbance in NO homeostasis. The clinical consequences are “endothelial dysfunction”, leading to “myocardial dysfunction”: no- or low-reflow phenomenon and temporary reduction of myocardial pump function. Uncoupling of eNOS (one electron transfer to molecular oxygen, the second substrate of eNOS) during ischemia-reperfusion due to diminished availability of L-arginine and/or tetrahydrobiopterin is even discussed as one major source of superoxide formation. Therefore maintenance of normal NO homeostasis seems to be an important factor protecting from ischemia/reperfusion (I/R) injury. Both, the clinical situations of cardioplegic arrest as well as hypothermic cardioplegic storage are followed by reperfusion. However, the presently used cardioplegic solutions to arrest and/or store the heart, thereby reducing myocardial oxygen consumption and metabolism, are designed to preserve myocytes mainly and not endothelial cells. This review will focus on possible drug additives to cardioplegia, which may help to maintain normal NO homeostasis after I/R