Abstract: A security measure is introduced that is based on informational divergence and that includes strong secrecy and stealth communication. The measure is applied to wire-tap channels and it is shown how the capacity region relates to Wyner's secrecy region. The converse follows by a short proof that uses a telescoping identity. The coding theorem is established by using a simple proof whose key step is applying Jensen's inequality to the logarithm, as well as a few typicality arguments. An operational meaning for stealth follows, in the usual way, by using binary hypothesis testing. The talk is based on joint work with Jie Hou from TUM. Bio: Gerhard Kramer is Alexander von Humboldt Professor and Head of the Institute for Communications Engineering at the Technische Universität München (TUM). He received the Dr. sc. techn. degree from the ETH Zürich, Switzerland, in 1998. From 1998 to 2000, he was with Endora Tech AG, Basel, Switzerland, as a communications engineering consultant. From 2000 to 2008 he was with the Math Center, Bell Labs, Alcatel-Lucent, Murray Hill, NJ, as a Member of Technical Staff. He joined the University of Southern California (USC), Los Angeles, CA, as a Professor of Electrical Engineering in 2009. He joined TUM in 2010. Gerhard Kramer's research interests are primarily in information theory and communications theory, with applications to wireless, copper, and optical fiber networks. He received several awards for his work, including an ETH Medal for his doctoral dissertation in 1999, a Bell Labs President's Gold Award in 2003, the IEEE Communications Society Stephen O. Rice Prize Paper Award in 2005, an Alexander von Humboldt Professorship in 2010, the Vodafone Innovations Prize in 2011, a Thomas Alva Edison Patent Award in 2012, and a EURASIP Best Paper Award in 2014. He is a Fellow of the IEEE since 2010.