The `OpenHTTPA` Foundation (openhttpa.org) The `OpenHTTPA` Foundation (openhttpa.org) OpenHTTPA (Hypertext Transfer Protocol with Attestation) defines a protocol for establishing hardware-verified, end-to-end confidential and authenticated communication between a client and a Trusted Execution Environment (TEE) over standard HTTP/2, HTTP/3, and gRPC transports. Unlike traditional TLS which terminates at the network edge, OpenHTTPA ensures that the cryptographic session terminates inside the hardware-isolated enclave. The protocol is based on the SIGMA-I model and incorporates post-quantum hybrid key exchange (ML- KEM), post-quantum digital signatures (ML-DSA), transcript-bound hardware attestation, and semantic binding of HTTP requests to the hardware-verified session state.