Galaxy Note 3

Enable Developer options

In Android 4.2 and later, developer options are disabled by default. To enable them, go to About Phone, and tap "Build Version" seven times. Now there's a "Developer options" in your settings, which can enable things like

• USB debugging (for use with the Android SDK),
• an advanced reboot menu, and
• hard-killing apps with a back button long-press.

Installing the CACert root certificate

The root certificate:

wget https://www.cacert.org/certs/root.crt
cat root.crt > 5ed36f99.0
openssl x509 -inform PEM -text -in root.crt -out /dev/null >> 5ed36f99.0

Rinse-and-repeat for the Class 3 certificate:

wget https://www.cacert.org/certs/class3.crt
cat class3.crt > e5662767.0
openssl x509 -inform PEM -text -in class3.crt -out /dev/null >> e5662767.0

Copy these two files onto your phone, then on your phone using the Terminal app:

su
mount -o remount,rw /system
cd /system/etc/security/cacerts/
cp /sdcard/5ed36f99.0 /sdcard/e5662767.0 .
chown root:root 5ed36f99.0 e5662767.0
chmod 644 5ed36f99.0 e5662767.0

Then reboot your phone.

Or use the Android SDK

If you can't be arsed typing all that into a terminal on your phone, fair enough, it's quite tedious. Instead, you can use the Android SDK to copy shit to your phone and run a shell:

~/android-sdk-linux/platform-tools/adb push e5662767.0 /sdcard/
~/android-sdk-linux/platform-tools/adb push 5ed36f99.0 /sdcard/
~/android-sdk-linux/platform-tools/adb shell

Then type it here instead. You'll need to enable USB debugging first, which is a developer feature (See above.)