Earlier quoted context omitted.
And it sounds like Apple is using a separate unspecified ARM processor (probably a Cortex-A5 since that's the cheapest possible one) to gain access to an existing A7 or A8 core.
In Apple's case, they use the ARM ISA but implement their own micro architecture and from vvhn's comment seems to also use a co-processor specifically for the secure enclave. But the link above on TrustZone hardware architecture mentions that this isn't a requirement. "TrustZone enables a single physical processor core to execute code safely and efficiently from both the Normal world and the Secure world. This remove…
I highly doubt they use their own micro architecture. It'd be a lot cheaper to license Cortex-A5. Using their own micro architecture for the main processor gives them a huge competitive advantage. For the security co-processor, COTS would work fine.