Confidential Blockchain

One of the fundamental challenges of TEE’s is the inability to hold a persistent state. This makes it difficult to know if the same code has been run more than once. There is a simple solution for how a blockchain allows us to deal with this:

• All communication with TEE happens through light-client based round trip.

• Create nonce and key on the enclave, commit to the contract, prove to enclave they’ve been committed.

• Light client checks contract state, contract can only execute on the latest state with an incrementing nonce.

• This stops replay attacks and prevents the enclave from being able to execute on arbitrary data.

The chain controls the code that gets executed!

Examples of this are found in Phala’s pRuntime and Tendermint’s light client.