Automatic make external hdds read-only

I want to reach, that every Storage-Device, which gets connected to the computer, is automatically read-only.

In Windows 7 there was an registry hack (StorageDevicePolicies -> WriteProtect) , but in Windows 8 this doesnt work any more.

So what is a suitable alternative?

PS: Not only users must not write on the hard drive, also windows self should not change the Data on the hdd.

Thank you