Update to 14.04 3.13.0-92 - Nvidia driver unsigned problem

Yesterday's update to 14.04 ( 3.13.0-92 ) requires that the keel video driver be signed.
I caot tu off secure boot as this is a dual-boot machine, Win 10 won't boot if secure boot is off.
The GUI logon screen boots to low-resolution, it loops on valid password entry.

After about a day of googling, am unable to determine which Nvidia drivers are signed,
which are not signed, and have not been able to find a signed driver.

Graphics card is GTX-660, the drivers tried are: 340.96 and 352.63. Rebooted to 3.13.0-91
and everything works fine (both 340.96 and 352.63). 352.63 is listed as 'recommended driver'
by the GUI.

Is there a place to find a signed nvidia driver? If not, what alteatives are available? If I ever
update to 16.04 apparently will have this same issue.

One search showed how to use nvidia-install which seems to be a script to install nvidia drivers,
and optionally allow signing from a MOK key. But that script is not present on this machine.
No such options for signing appear when using the 'Software & Updates' Additional Drivers GUI to
update drivers.

-- Tom McDermott

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