Security is a big thing on Skype. From day 1 and even before in the core architecture design, we've taken security seriously and continue to do so. For those interested in digging in to the subject, I'm happy to introduce our [security blog](http://share.skype.com/sites/security/) with Kurt Sauer, Skype's CSO (Chief Security Officer), taking the lead. For starters, see Kurt's introductory comments on Skype's PKI model.