I want to install Rstudio for ubuntu, so I used the link https://www.rstudio.com/products/rstudio/download/ after that I choosen RStudio 0.99.893 - Ubuntu 12.04+/Debian 8+ (64-bit) then I opened with Ubuntu software center. In that I clicked the install button I got error box like this,
Requires installation of untrusted packages
This requires installing packages from unauthenticated sources.
How to solve this problem?