# Ratify Protocol > The Ratify Protocol is an open cryptographic trust protocol for human-to-agent and agent-to-agent authorization. Every signature is hybrid Ed25519 + ML-DSA-65 (NIST FIPS 204) — quantum-safe by design. Four reference SDKs (Go, TypeScript, Python, Rust) produce byte-identical canonical JSON and verify each other's proofs. Maintained by Identities AI, Inc. License: Apache-2.0 (code), CC-BY-4.0 (spec). Patent pending. Three-verb model: **Delegate** (a principal signs a `DelegationCert` granting scopes), **Present** (the agent signs a fresh challenge to prove liveness), **Verify** (any third party checks the bundle in < 1 ms, offline, no central authority). Wire format is JSON, fixtures are byte-identical across all SDKs, and the protocol works with no blockchain, no tokens, and no central issuer. Ratify Verify is the commercial managed layer maintained by Identities AI. The protocol and SDKs are free forever; Verify adds the operational surface — push-based revocation, no-code policy management, signed audit chain, SSO-bound identity attestation, and last-mile platform adapters (Zoom, Twilio, AWS API Gateway, …) — that's hard to rebuild at scale. ## Start here - [Ratify Protocol](https://docs.identities.ai/): Cryptographic identity and authorization for AI agents — open protocol, five SDKs, byte-for-byte interop. - [Protocol vs. Verify](https://docs.identities.ai/start/protocol-vs-verify/): How the open Ratify Protocol, the reference SDKs, and the commercial Ratify Verify product fit together. - [Quickstart](https://docs.identities.ai/start/quickstart/): Install a Ratify SDK in your language of choice and verify the conformance suite in under 60 seconds. ## Protocol concepts - [Delegate, Present, Verify](https://docs.identities.ai/concepts/delegate-present-verify/): The three verbs that compose the entire protocol, illustrated with byte-level detail. - [Provider architecture & the build-vs-buy boundary](https://docs.identities.ai/concepts/provider-architecture/): How the Ratify Protocol stays open while Ratify Verify holds the operational moat — the four hook points and four optional levers introduced in v1.0.0-alpha.7. - [Scopes](https://docs.identities.ai/concepts/scopes/): The canonical 53-scope vocabulary, the 14 wildcards, the sensitive-scope rule, and the `custom:` extension pattern. - [Constraints](https://docs.identities.ai/concepts/constraints/): First-class bounds on when, where, and how much an agent may exercise a scope. - [Challenges & freshness](https://docs.identities.ai/concepts/challenges/): The challenge-response mechanism that turns a static cert into a live-key proof. - [Revocation](https://docs.identities.ai/concepts/revocation/): Signed revocation lists and the RevocationProvider hook for stopping a cert before it naturally expires. - [Key custody](https://docs.identities.ai/concepts/key-custody/): Three custody modes for principal keys — self-custody, custodial, and self-custody upgrade — with their threat models. - [Hybrid post-quantum crypto](https://docs.identities.ai/concepts/hybrid-pqc/): Why every Ratify signature is two signatures, what each algorithm contributes, and what threats hybrid mode actually defends against. ## SDKs - [SDK packages](https://docs.identities.ai/sdk/packages/): Where each SDK is published, current versions, and how to verify byte-for-byte interop. - [Go SDK](https://docs.identities.ai/sdk/go/): Use the Go reference SDK to issue delegations, build proof bundles, and verify them. - [TypeScript SDK](https://docs.identities.ai/sdk/typescript/): Use the TypeScript reference SDK to issue delegations, build proof bundles, and verify them. - [Python SDK](https://docs.identities.ai/sdk/python/): Use the Python reference SDK to issue delegations, build proof bundles, and verify them. - [Rust SDK](https://docs.identities.ai/sdk/rust/): Use the Rust reference SDK to issue delegations, build proof bundles, and verify them. ## Integration guides - [Meetings](https://docs.identities.ai/guides/meetings/): Pre-announce and verify AI agents before they join meetings. - [Voice](https://docs.identities.ai/guides/voice/): Verify and authorize live voice agents, telephony bots, and speaking surfaces with Ratify. - [API Gateway](https://docs.identities.ai/guides/api-gateway/): Require Ratify proofs before MCP, A2A, finance, or REST requests reach application code. - [Physical AI](https://docs.identities.ai/guides/physical-ai/): Verify Ratify proofs on robots, vehicles, drones, and infrastructure. - [Model Context Protocol (MCP)](https://docs.identities.ai/guides/mcp/): Verify Ratify proofs before an MCP server executes a tool call. - [Agent-to-Agent (A2A)](https://docs.identities.ai/guides/a2a/): Patterns for one agent transacting with, hiring, or sub-delegating to another agent. ## Ratify Verify (commercial) - [Commercial Ratify Platform](https://docs.identities.ai/verify/overview/): How a developer registers with Ratify, connects an agent platform, and uses the commercial surfaces. - [Agent Platform Integration](https://docs.identities.ai/verify/platform-onboarding/): How an agentic platform integrates Ratify Protocol and the commercial Ratify surface. - [Callbacks and Webhooks](https://docs.identities.ai/verify/callback-contract/): What Ratify sends to your callback URL and what your platform must implement. - [Pricing](https://docs.identities.ai/verify/pricing/): The protocol is free forever. Ratify Verify charges per verification for the managed verifier, and on annual contract for compliance-grade trust and sovereign deployments. ## Reference - [Specification](https://docs.identities.ai/reference/spec/): Where the normative specification lives and how to read it. - [Versioning](https://docs.identities.ai/reference/versioning/): How protocol versions and SDK versions work, when fixture bytes can change, and the alpha → stable ladder. - [Conformance suite](https://docs.identities.ai/reference/conformance/): The 59 canonical test vectors that define byte-for-byte interop across every Ratify implementation. - [Glossary](https://docs.identities.ai/reference/glossary/): Every Ratify term, defined. ## Optional - [C / C++ SDK](https://docs.identities.ai/sdk/c/): Static and shared libraries for embedded, RTOS, and native C/C++ targets. cbindgen header, no_std + alloc compatible.