Agent Attestation Protocol - The Reverse Turing Test. Verify AI agents, block humans.
**Added cryptographic identity requirement for agent verification.** - Clients must now sign their challenge responses with a secp256k1 key pair; anonymous access is disallowed. - New protocol flow includes sending publicKey, signature, and timestamp for provable identity. - New server option requireSignature (default: true) enforces cryptographic proof. - SKILL.md and code updated to document and implement these signing requirements. - Security model strengthened with non-repudiation and traceable agent actions.