Skype is a closed source application that is now controlled by a corporation that openly works with LE and provides tools like this: https://en.wikipedia.org/wiki/Computer_Online_Forensic_Evidence_Extractor You should put zero trust in Skype. You should not do anything sensitive on the same computer/OS where Skype is installed. If for some reason you need to use Skype, do your sensitive stuff in Tails or on a separate computer.