[U-Boot] Secure update of uboot devices?

[Marek Vasut]

> With the new threats like Stuxnet and Duqu one need to improve on how new
> updates to software is distrubuted to devcies so one can
> be sure that it's not a hacked or modified software that runs in the
> device. We use uboot + usb stick to update the software in our devices.
> Have anyone been trying out to add e.g cryptated,certificates or rsa keys
> to uboot?

sha1sum of the file isn't enough?