You will not be able to perform disk encryption operations if there is a problem with PGPwde.kext.
I have seen this issue a few times on Mavericks, and it can often be fixed by simply performing a reinstallation over the top of the existing installation. For some reason, on the initial installation, it has an issue installing the kernel extension, and I don't know if a reason has been discovered yet, as it happens infrequently, and is near impossible to reproduce (since uninstall/reinstall or an over-the-top reinstall both will fix it).
Let me know if the issue persists after reinstallation.