Trustzone is a hardware virtual processor which would run all secure code. You'll see something similar in future Intel chips.
As for specific instructions for encryption/random number generation, ARM doesn't contain any. In embedded applications you'll often find hardware random number generators and encryption engines. For real end user computing there is no ARM standard.
Getting back to Apple. At this stage it doesn't matter how good (or bad) ARM performance is as there is no ARM 64 bit core. This should be announced in the next few months. Very little is known about this core and it's capabilities, it could be designed for deeply embedded applications and not end user computing at all.