Observability Analysis

In this paper we show that, paradoxically, what looks like a “universal improvement” or a “straight-forward improvement” which enables better security and better reliability on a theoretical level, may in fact, within certain operational contexts, introduce new exposures and attacks, resulting in a weaker operational cryptosystem. We demonstrate a number of such dangerous “improvements”. This implies that careful considerations should be given to the fact that an implemented cryptosystem exists within certain operational environments (which may enable certain types of tampering and other observed information channels via faults, side-channel attacks or behavior of system operators). We use our case studies to draw conclusions about certain investigations required in studying implementations and suggested improvements of cryptosystems; looking at them in the context of their operating environments (combined with their potential adversarial settings). We call these investigations observability analysis.