rfc/specs/waku/v2/waku-message.md

title	version	status	authors
Waku Message	2.0.0-beta1	Draft	Oskar Thorén <oskar@status.im>

Table of Contents

• Abstract
• Motivation
• WakuMessage
  • Protobuf
  • Payload encryption
    • Version 0
    • Version 1
• Differences from Whisper / Waku v1 envelopes
• Changelog
• Copyright

Abstract

This specification provides a way to encapsulate messages sent over Waku with specific information security goals.

Motivation

When using Waku to send messages over Waku there are multiple concerns:

• We may have a separate encryption layer as part of our application
• We may want to provide efficient routing for resource restricted devices
• We may want to provide compatibility with Waku v1 envelopes
• We may want payloads to be encrypted by default
• We may want to provide unlinkability for metadata protection

This specification attempts to provide for these various requirements.

WakuMessage

A WakuMessage is what is being passed around by the other protocols, such as WakuRelay, WakuStore, and WakuFilter.

The payload field SHOULD contain whatever payload is being sent. See section below on payload encryption.

The contentTopic field SHOULD be filled out to allow for content-based filtering. See Waku Filter spec for details.

The version field MAY be filled out to allow for various types of payload encryption. Omitting it means the version is 0.

Protobuf

message WakuMessage {
  optional bytes payload = 1;
  optional fixed32 contentTopic = 2;
  optional string version = 3;
}

Payload encryption

Payload encryption depends on the version field.

Version 0

This indicates that the payload SHOULD be either unencrypted or that encryption is done at a separate layer outside of Waku.

Version 1 (not yet implemented in Waku v2)

This indicates that payloads MUST be encrypted using Waku v1 envelope data format spec.

This provides for asymmetric and symmetric encryption. Key agreement is out of band. It also provides an encrypted signature and padding for some form of unlinkability.

Differences from Whisper / Waku v1 envelopes

In Whisper and Waku v1, an envelope contains the following fields: expiry, ttl, topic, data, nonce.

Since Waku v2 is using libp2p PubSub, some of these fields can be dropped. The previous topic field corresponds to contentTopic. The previous data field corresponds to the payload field.

Changelog

Initial release on 2020-10-22.

Copyright

Copyright and related rights waived via CC0.