Unable to install rpi-update

[StormTrooper]

Running Raspbmc and trying to do a kernel update:

First using apt-get I get a error trying to install rpi-update.

root@raspbmc:~# sudo apt-get install rpi-update
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package rpi-update

Then tried the manual install using:
sudo wget https://raw.github.com/Hexxeh/rpi-update/master/rpi-update -O /usr/bin/rpi-update && sudo chmod +x /usr/bin/rpi-update

and get:

--2014-03-21 16:07:00-- https://raw.github.com/Hexxeh/rpi-update/master/rpi-update
Resolving raw.github.com (raw.github.com)... 185.31.16.133
Connecting to raw.github.com (raw.github.com)|185.31.16.133|:443... connected.
ERROR: The certificate of raw.github.com' is not trusted. ERROR: The certificate ofraw.github.com' hasn't got a known issuer.

Any ideas?

[popcornmix]

Duplicate of #65