A secure boundary is sufficient for confidential computing.
A secure boundary is necessary for confidential computing, but it is not sufficient. There must also be a way to establish trust with the target compute environment that the boundary is protecting (the TEE). Trust needs to be built by a process that is both explicit and transparent. This process is known as attestation.
The CCA attestation token is divided at the top level into two sub-tokens.
The CCA attestation token is divided at the top-level into the platform token and the realm token.