Implement Complete Knowledge (CK) on TEE

[LillieH]

CK is a cryptographic primitive to prove that a key is controlled by a single person - so would be very useful for KYC/AML. Generation of CK proofs currently needs special hardware like SGX or mining ASIC. The main challenge is availability and developer (un)friendliness of these hardware resources.

Background information:
https://docs.google.com/presentation/d/1sSMpq-CiM9N6BqogTmI_Doghwo8TRXgsV-KE7lSfdUI/edit?usp=drivesdk
https://slideslive.com/38920016/designing-smart-contracts-with-free-will