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CRP-SPEC-001: Core Protocol Specification

Document: CRP-SPEC-001
Title: Context Relay Protocol (CRP) — Core Specification
Version: 3.0.0
Status: Draft
Author: Constantinos Vidiniotis, AutoCyber AI Pty Ltd
Contact: contact@crprotocol.io
Date: 2026-05-24
License: CC BY 4.0 (specification text) / Proprietary (implementation)

Abstract

The Context Relay Protocol (CRP) defines a structured, language-agnostic protocol for managing AI context, safety governance, and compliance evidence in deployed large language model (LLM) systems. CRP operates as an HTTP-compatible sidecar protocol, enriching every AI request/response cycle with standardised headers carrying context quality, hallucination risk, provenance integrity, and regulatory classification metadata.

This document defines the foundational axioms, request/response model, sidecar architecture, and the normative relationship between CRP's subsystems: the Context Envelope, Contextual Knowledge Fabric (CKF), Decision Provenance Engine (DPE), and the Audit Chain.

Status of This Document

This is a working draft of the CRP Core Specification. It is published for review and comment. Feedback may be submitted via email 'contact@autocyberai.com' or 'contact@crprotocol.io' or soon at the CRP GitHub repository at github.com/crprotocol/spec.

This document is intended for submission as an IETF Internet-Draft targeting the Applications and Real-Time Area (ART).

1. Introduction

1.1 Background

Large language model systems deployed in production lack a standardised mechanism for communicating the quality, safety, and compliance state of their outputs to consuming applications, intermediary services, and governance platforms. Each system operator builds bespoke instrumentation to capture hallucination risk, session state, and audit trails — leading to fragmented, non-interoperable approaches.

The Context Relay Protocol addresses this gap by defining:

  • A wire-level header vocabulary (see CRP-SPEC-002) analogous to HTTP headers, carrying AI-specific metadata on every request/response
  • A session state relay mechanism (see CRP-SPEC-007) analogous to HTTP cookies, enabling stateless context continuity
  • A safety policy directive language (see CRP-SPEC-006) analogous to Content Security Policy, enabling declarative AI safety enforcement at the transport layer
  • A provenance and audit chain (see CRP-SPEC-011) enabling tamper-evident, cryptographically verifiable compliance evidence

1.2 Relationship to Existing Protocols

CRP is designed to complement, not replace, existing AI agent protocols:

Protocol Role CRP Relationship
MCP (Model Context Protocol) Tool/resource access for agents CRP governs the AI calls MCP agents make
A2A (Agent-to-Agent) Inter-agent communication CRP headers propagate safety state across A2A hops
OpenAI API LLM inference CRP gateway proxies OpenAI-compatible endpoints
HTTP/1.1, HTTP/2 Transport CRP headers are carried as standard HTTP header fields

1.3 Goals

  1. Provide a universal, language-agnostic metadata contract for AI request/response cycles
  2. Enable safety enforcement at the transport layer, not the application layer
  3. Generate continuous compliance evidence without developer instrumentation
  4. Remain compatible with all major LLM providers and agent frameworks
  5. Be implementable as an RFC-based open standard

1.4 Non-Goals

  • CRP does not modify LLM model weights or training
  • CRP does not replace application-level business logic
  • CRP does not mandate a specific LLM provider
  • CRP does not define agent behaviour beyond the dispatch interface

2. Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174].

AI call: A single request/response cycle to a large language model.

CRP Gateway: An HTTP-compatible reverse proxy that implements the CRP protocol, sitting between a client application and one or more LLM providers.

Context Envelope: The structured set of facts, knowledge fragments, and instructions assembled by the CRP gateway for injection into an LLM request.

Contextual Knowledge Fabric (CKF): The persistent fact graph (Tier 3 of the CRP memory hierarchy) from which Context Envelopes are assembled.

Decision Provenance Engine (DPE): The CRP module responsible for post-generation analysis of LLM outputs, producing hallucination risk scores, attribution analysis, and provenance records.

Safety Budget: A session-scoped counter representing remaining risk tolerance, decremented by each high-risk AI call. Exposed as CRP-Agent-Safety-Budget.

Window: A single AI call within a continuation chain. Windows are connected in a directed acyclic graph (DAG) for context enlargement across multiple calls.

3. The Ten Axioms

CRP's design is governed by ten foundational axioms. All conformant CRP implementations MUST uphold these axioms.

Axiom 1 — Completeness: The Context Envelope MUST include all factual content necessary for the LLM to answer the query without reliance on parametric memory, where such content exists in the CKF.

Axiom 2 — Accuracy: Facts included in the envelope MUST be drawn from verified source material. The DPE MUST assess output accuracy against envelope content.

Axiom 3 — Relevance: The envelope packing algorithm MUST prioritise facts by relevance score. Irrelevant facts MUST NOT consume token budget at the cost of relevant facts.

Axiom 4 — Transparency boundary: CRP headers MUST NOT be forwarded to LLM providers. The model MUST remain ignorant of the protocol layer.

Axiom 5 — Oversight capability: All CRP implementations MUST support human oversight triggering. The CRP-Oversight-Mode: halt directive MUST be honoured unconditionally.

Axiom 6 — Resource constraint awareness: The gateway MUST track token budget consumption and expose it via CRP-Context-Tokens-Used and CRP-Context-Window headers.

Axiom 7 — Provenance integrity: Every AI call MUST produce a tamper-evident audit record. HMAC chain integrity MUST be verifiable by any party holding the session key.

Axiom 8 — Continuity: Continuation sessions MUST preserve context quality across window boundaries. The CRP-Context-Continuation-Id header MUST enable stateless session relay.

Axiom 9 — Regulatory alignment: CRP outputs MUST be classifiable against EU AI Act, GDPR, NIST AI RMF, and ISO 42001 frameworks. Classification MUST be emitted as response headers.

Axiom 10 — Provider neutrality: CRP MUST support any LLM provider exposing an OpenAI-compatible API. Provider selection MUST be transparent to consuming applications.

4. Protocol Architecture

4.1 Overview

┌─────────────────────────────────────────────────────────┐
│                    Client Application                    │
│  (sends CRP-Accept-*, CRP-Safety-Policy, CRP-Session)   │
└────────────────────────┬────────────────────────────────┘
                         │ HTTP request with CRP req headers
                         ▼
┌─────────────────────────────────────────────────────────┐
│                     CRP Gateway                          │
│  ┌──────────┐  ┌──────────┐  ┌──────────┐  ┌────────┐  │
│  │ Envelope │  │  DPE     │  │  Audit   │  │  Comply│  │
│  │ Builder  │  │ (Safety) │  │  Chain   │  │  Feed  │  │
│  └──────────┘  └──────────┘  └──────────┘  └────────┘  │
└────────────────────────┬────────────────────────────────┘
                         │ Stripped request (no CRP headers)
                         ▼
┌─────────────────────────────────────────────────────────┐
│                   LLM Provider                           │
│         (OpenAI / Anthropic / Gemini / Ollama)           │
└─────────────────────────────────────────────────────────┘

4.2 Request Flow

  1. Client sends HTTP request to CRP gateway with optional CRP request headers
  2. Gateway authenticates request using CRP API key
  3. Gateway checks CRP-Context-If-Match — returns 304 if ETag matches
  4. Gateway assembles Context Envelope from CKF (3-phase: select, rank, pack)
  5. Gateway selects dispatch strategy from CRP-Accept-Strategy or TaskIntent detection
  6. Gateway strips all CRP headers, forwards packed request to LLM provider
  7. LLM provider returns raw completion
  8. Gateway runs DPE pipeline on completion (13 modules)
  9. Gateway evaluates completion against CRP-Safety-Policy
  10. If policy violation (e.g., halt-on CRITICAL): returns HTTP 451, fires report-uri webhook
  11. Gateway injects all response CRP headers
  12. Gateway updates HMAC chain, issues updated CRP-Set-Session token
  13. Gateway streams audit event to CRP Comply (if configured)
  14. Gateway returns response with CRP headers to client

4.3 Memory Hierarchy

CRP implements a four-tier memory hierarchy:

Tier Name Latency Persistence CRP Header
0 Active (in-context) <1ms Call-scoped CRP-Context-Window
1 Hot (session cache) <10ms Session-scoped CRP-Context-Session-Id
2 Warm (recent CKF) <100ms Cross-session CRP-Memory-CKF-Hits
3 Cold (full CKF graph) <1000ms Persistent CRP-Memory-Knowledge-Age

5. Conformance Levels

CRP defines three conformance levels:

CRP-Basic: Implements core headers (CRP-Context-Quality-Tier, CRP-Safety-Hallucination-Risk, CRP-Provenance-HMAC), session tokens, and HTTP 451 halt. Minimum viable governance.

CRP-Standard: Implements all 58 headers, Safety Policy directives, ETag caching, agentic dispatch headers, and compliance headers. Required for CRP Comply integration.

CRP-Full: Implements all of Standard plus streaming safety enforcement, stop-sequence injection, multi-agent safety budget propagation, and SIEM export. Required for CRP Certification.

6. Security Considerations

6.1 Header Injection

CRP headers on responses MUST be generated by the CRP gateway, not by LLM output. Implementations MUST validate that no CRP-prefixed headers are present in raw LLM responses before injection.

6.2 Session Token Security

The CRP-Set-Session token MUST be signed with HMAC-SHA256 using a session key not derivable from the token payload. Tokens MUST include an expiry and MUST NOT be accepted after expiry.

6.3 HMAC Chain Integrity

The HMAC chain MUST be computed as: HMAC-SHA256(window_content || previous_HMAC, session_key). Any break in the chain (verified via CRP-Provenance-Chain-Integrity: BROKEN) MUST trigger an audit incident.

6.4 LLM Provider Credentials

CRP gateways that vault LLM provider credentials MUST store keys encrypted at rest. Client applications MUST NOT be required to hold LLM provider credentials when using a CRP gateway.

7. IANA Considerations

This document requests registration of the CRP- prefix in the HTTP Field Name Registry at https://www.iana.org/assignments/http-fields per RFC 9110 Section 16.3.

A complete list of headers for registration is provided in CRP-SPEC-002 (Header Specification).

8. References

Normative References

  • [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels"
  • [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words"
  • [RFC9110] Fielding, R. et al., "HTTP Semantics"
  • [RFC6265] Barth, A., "HTTP State Management Mechanism"

Informative References

  • EU AI Act (Regulation 2024/1689)
  • ISO/IEC 42001:2023, Artificial Intelligence Management Systems
  • NIST AI RMF 1.0
  • GDPR (Regulation 2016/679)
  • draft-rosenberg-aiproto-framework, "Framework for AI Agent Protocols"

Appendix A: Glossary

See Section 2 (Terminology).

Appendix B: Change History

Version Date Changes
1.0.0 2024-01-01 Initial protocol release
2.0.0 2024-06-01 DPE integration, HMAC chain
3.0.0 2026-05-24 Header specification, Safety Policy, Session Token

Copyright © 2025–2026 AutoCyber AI Pty Ltd. This specification text is licensed under CC BY 4.0. The CRP™ name and logo are trademarks of AutoCyber AI Pty Ltd.