This article examines women's covert use of contraceptives, that is, their use of a method without their husbands' knowledge. Three questions are addressed: (1) How is covert use measured? (2) How prevalent is it? and (3) What are the factors underlying covert use? Existing studies are used together with survey and qualitative data collected in 1997 in an urban setting in Zambia from married wo...

Covert channels are a security threat for information systems, since they permit illegal flows, and sometimes leaks, of classified data. Although numerous descriptions have been given at a concrete level, relatively little work has been carried out at a more abstract level, outside probabilistic models. In this paper, we propose a definition of covert channels based on encoding and decoding bin...

Covert channels are used for the secret transfer of information. Encryption only protects communication from being decoded by unauthorised parties, whereas covert channels aim to hide the very existence of the communication. Initially, covert channels were identified as a security threat on monolithic systems i.e. mainframes. More recently focus has shifted towards covert channels in computer n...

The topic of covert acoustical communication in air has produced public attention, lately. In 2013, we presented the fact that infected drones (e.g. laptops) might form covert acoustical mesh networks in air, only utilizing the built-in speakers and microphones. In this article, we aim to present the current state of covert acoustical communication in air. We discuss future forms of covert acou...

INTRODUCTION Even though people with congenital prosopagnosia (CP) never develop a normal ability to "overtly" recognize faces, some individuals show indices of "covert" (or implicit) face recognition. The aim of this study was to demonstrate covert face recognition in CP when participants could not overtly recognize the faces. METHODS Eleven people with CP completed three tasks assessing the...

In a real-world network, different hosts involved in covert channel communication run different covert channel software as well as different versions of such software, i.e. these systems use different network protocols for a covert channel. A program that implements a network covert channel for mobile usage thus must be capable of utilizing multiple network protocols to deal with a number of di...