While trying to sue rpi-update for the first time I also had this problem.
I did had ca-certificates installed and the date was right, but found a solution.
At least in archlinux (it might work in debian too), if you get this error and your date are ok, and have ca-certificates installed, do with root privileges:
[code] update-ca-certificates --fresh[/code]
When you have time had this to the readme Hexxeh.
Tks for your work:)
Frankly, this should be done by default in the Arch image, any any Pi image, really.
This stuff comes preinstalled as standard on any modern distro...
I think ca-certificates comes installed. but the certificates weren't updated (probably generated with wront time or something..) or generated.
If it should or not come by default, I think that's more specific to the distro. Arch isn't supposed to come with anything, you're supposed to go get what you want.
after the ca refresh, you need reboot.....