Leibniz University of Hanover

About: Leibniz University of Hanover is a education organization based out in Hanover, Niedersachsen, Germany. It is known for research contribution in the topics: Finite element method & Population. The organization has 14283 authors who have published 29845 publications receiving 682152 citations.

Rethinking SSL development in an appified world

Abstract: The Secure Sockets Layer (SSL) is widely used to secure data transfers on the Internet. Previous studies have shown that the state of non-browser SSL code is catastrophic across a large variety of desktop applications and libraries as well as a large selection of Android apps, leaving users vulnerable to Man-in-the-Middle attacks (MITMAs). To determine possible causes of SSL problems on all major appified platforms, we extended the analysis to the walled-garden ecosystem of iOS, analyzed software developer forums and conducted interviews with developers of vulnerable apps. Our results show that the root causes are not simply careless developers, but also limitations and issues of the current SSL development paradigm. Based on our findings, we derive a proposal to rethink the handling of SSL in the appified world and present a set of countermeasures to improve the handling of SSL using Android as a blueprint for other platforms. Our countermeasures prevent developers from willfully or accidentally breaking SSL certificate validation, offer support for extended features such as SSL Pinning and different SSL validation infrastructures, and protect users. We evaluated our solution against 13,500 popular Android apps and conducted developer interviews to judge the acceptance of our approach and found that our solution works well for all investigated apps and developers.

Cell wall pectin content modulates aluminium sensitivity of Zea mays (L.) cells grown in suspension culture

Abstract: The pectin content of the cell walls of maize suspension cells was modified to investigate its role in the expression of aluminium (Al) toxicity. Long-term adaptation to NaCI or to the cellulose synthesis inhibitor 2,6-dichlorbenzonitirle (DCB) increased the pectin content by 31 and 86%, respectively. Subculturing salt-adapted cells for up to 3 weeks without NaCI supply or treatment of cells with pectolyase for up to 15 min reduced pectin contents by up to 46%. Such pre-cultured cells were incubated for 2 h in presence of Al. There was a close positive correlation between pectin and both total and BaCl 2 non-exchangeable Al contents. Aluminium-induced callose formation as an indicator of Al injury was closely positively correlated to the loss of cell viability. In NaCI-adapted and pectolyase-treated cells, Al-induced callose formation was reduced when compared with normal cells. However, there was a close positive relationship between pectin contents and relative callose induction (digitonin-induced callose formation, reflecting the different capabilities of cells to synthesize callose set to 100%) indicating that cells with higher pectin contents are more Al-sensitive. The results presented support our view that the binding of Al to the cell wall pectin-matrix represents an important step in the expression of Al toxicity.

Development of an implicit method with numerical dissipation from a generalized ingle-step algorithm for structural dynamics

Abstract: A new generalized algorithm in the class of single-step time marching schemes is developed for the solution of the dynamic equation of motion. The algorithm has six independent parameters and is derived from a new concept of separate time approximation. The generalized algorithm includes various known methods. The truncation error, spectral stability, and overshooting behaviour of the new algorithm are investigated theoretically. On the basis of the results, some of the six free parameters of the generalized algorithm are adjusted systematically. This leads to a new implicit method with one independent parameter. The new method is unconditionally stable and of secondorder accuracy. The numerical dissipation can be controlled.