Cannot update packages (keyring issue)

[Joe Riel]

I have Emacs 25 and cannot update the package list, or install packages,
because, apparently, the keyring is out-of-date.  I saw a reference to
a new package gnu-elpa-keyring-update, that is supposed to solve the
problem, but, naturally, package-install won't work because of the 
above issue.  

What's the best way to fix this?  Will the package work with Emacs 25?

-- 
Joe Riel