Add Agent Identity Protocol (AIP) to Related Protocols

[The-Nexus-Guard]

What is this?

Adds AIP (Agent Identity Protocol) to the Related Protocols & Concepts section.

Why does it belong here?

AIP solves the agent identity and authentication problem that A2A's Agent Card model leaves to implementers. Specifically:

• Ed25519 cryptographic identity — agents generate key pairs and derive DIDs (Decentralized Identifiers)
• Trust vouching — agents cryptographically endorse each other, building verifiable trust chains
• Encrypted messaging — end-to-end encrypted agent-to-agent communication
• A2A interop — there's an active PR on the A2A repo specifying how AIP DIDs extend Agent Cards for identity verification

Project stats

• PyPI: pip install aip-identity (~69 installs/day)
• 309 tests, 13 registered agents with active vouch chains
• Live API at aip-service.fly.dev
• MIT licensed