AEX: Non-Intrusive Multi-Hop Attestation and Provenance for LLM APIs

Researchers propose AEX, a new attestation protocol for LLM APIs that provides cryptographic proof that API responses actually correspond to client requests. The system addresses trust issues with hosted AI models by adding signed attestation objects to existing JSON-based APIs without disrupting current functionality.

• →AEX protocol enables cryptographic verification of LLM API responses without modifying existing API semantics.
• →The system addresses trust issues where intermediary or shadow APIs may diverge from claimed behavior.
• →AEX supports streaming outputs, tool-calling, and trusted intermediaries through signed receipts.
• →The protocol includes an OpenAI-compatible implementation with TypeScript prototype and conformance tests.
• →AEX makes a narrow but important claim by binding client requests to verified outputs at the API boundary.