Reputation Security Protocol (RepSec)

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Table of Contents

1. Introduction

Current approaches to reputation and security metadata are fragmented and proprietary. RepSec provides a standardized protocol for secure, interoperable exchange of this information. The protocol is designed to be simple to implement, secure by default, and extensible for future needs, drawing on SMTP's command/response model and SNMP's extensible object framework.¶

Goals:¶

- Simple, JSON-based message exchange
- Secure by default (TLS mandatory)
- Extensible command set and object schemas
- Open and free to implement¶

2. Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119] and [RFC8174] when, and only when, they appear in all capitals, as shown here.¶

3. Protocol Overview

RepSec uses a client/server request–response model.¶

Transport: TCP with mandatory TLS (TLS 1.2 or later; TLS 1.3 SHOULD be supported).
Port: TBD by IANA (proposed: 4655).
Encoding: UTF-8 JSON for commands and responses.
Status Codes: Numeric, modeled after SMTP.¶

4. Terminology

Client: entity initiating RepSec commands.
Server: entity providing RepSec services.
Entity: subject of registration (domain, IP, userID, organization, etc.).
Message: JSON-encoded RepSec command or response.
Extension: optional module that defines new commands and/or schemas.¶

5. Protocol Elements

{ "command": "REGISTER", "entity": "example.com", "type": "domain", "auth": "token123" }

{ "command": "VERIFY", "entity": "example.com" }

{ "command": "REMOVE", "entity": "example.com" }

{ "command": "AUDIT", "entity": "example.com" }

{ "command": "PING" }

200 OK                Command succeeded
400 BAD REQUEST       Syntax error or missing parameters
401 UNAUTHORIZED      Authentication required or failed
403 FORBIDDEN         Command not permitted
404 NOT FOUND         No such entity or resource
409 CONFLICT          State conflict (e.g., already registered)
429 TOO MANY REQUESTS Rate limiting in effect
500 SERVER ERROR      Internal processing error

{ "status": 200, "message": "Entity registered successfully" }

C: { "command": "REGISTER", "entity": "example.com", "type": "domain" }
S: { "status": 200, "message": "Entity registered successfully" }

C: { "command": "VERIFY", "entity": "example.com" }
S: { "status": 200, "verified": true, "last_updated": "2025-09-02T10:00:00Z" }

6. Security Considerations

All RepSec sessions MUST use TLS with server authentication; mutual authentication via client certificates or token-based schemes is RECOMMENDED. Implementations MUST provide replay protection (e.g., timestamps and nonces) and SHOULD employ rate limiting and abuse detection. Privacy by design: servers MUST NOT expose unnecessary metadata and SHOULD minimize data retention.¶

7. Extensibility

RepSec supports extensions similar to SMTP EHLO and SNMP MIBs. Extensions MAY define new commands and/or JSON schemas (RepSec Object Definitions). Servers SHOULD advertise supported extensions during capability discovery (future work).¶

8. IANA Considerations

IANA is requested to assign a new TCP port for RepSec (suggested: 4655) and to create a new "RepSec Parameters" registry containing:¶

- Registered RepSec Commands (Specification Required)
- Registered RepSec Extensions (Specification Required)
- Status Codes (Standards Action)¶

9. Licensing and IPR

This specification is made available under the IETF Trust Legal Provisions Relating to IETF Documents (TLP). Implementations may be licensed under permissive or copyleft licenses (e.g., Apache-2.0, GPL/LGPL), provided interoperability with the open standard is maintained. "RepSec" may be used as a trademark to indicate interoperable implementations.¶

Appendix A. Acknowledgments

RepSec was inspired by the simplicity of SMTP and the extensibility of SNMP, with the goal of creating an open, non-proprietary Internet standard for reputation security.¶

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