According [to this](https://wiki.archlinux.org/index.php/Skype#Securing_Skype) there are compelling reasons for caution when installing obfuscated binaries. Knowing this, how can running [binary blobs](https://en.wikipedia.org/wiki/Binary_blob) as a part of the Linux kernel be acceptable from a security point of view? There exists a [blob-free version of the kernel](https://en.wikipedia.org/wiki/Linux-libre). The motivations behind that project seem to be primarily ideological. But what kind of risks do users of non-free driver modules actually face? Can a binary blob contain a rootkit designed to take over or open a backdoor into the entire system? How could such a backdoor be detected?