Waku Bridge Source

AuthorsKim De Mey
StatusRaw
Version2.0.0-alpha1

Table of Contents

TODO

Abstract

A bridge between Waku v1 and Waku v2.

Bridge

A bridge requires supporting both Waku versions:

  • Waku v1 - using devp2p RLPx protocol
  • Waku v2 - using libp2p protocols

Packets received on the Waku v1 network SHOULD be published just once on the Waku v2 network. More specifically, the bridge SHOULD publish this through the Waku Relay (PubSub domain).

Publishing such packet will require the creation of a new Message with a new WakuMessage as data field. The data and topic field from the Waku v1 Envelope MUST be copied to the payload and contentTopic fields of the WakuMessage. Other fields such as nonce, expiry and ttl will be dropped as they become obsolete in Waku v2.

Before this is done, the usual envelope verification still applies:

  • Expiry & future time verification
  • PoW verification
  • Size verification

Bridging SHOULD occur through the WakuRelay, but it MAY also be done on other Waku v2 protocols (e.g. WakuFilter). The latter is however not advised as it will increase the complexity of the bridge and because of the Security Considerations explained further below.

Packets received on the Waku v2 network SHOULD be posted just once on the Waku v1 network. The Waku v2 WakuMessage contains only the payload and contentTopic fields. The bridge MUST create a new Waku v1 Envelope and copy over the payload and contentFilter fields to the data and topic fields. Next, before posting on the network, the bridge MUST set a new expiry and ttl and do the PoW nonce calculation.

Security Considerations

As mentioned above, a bridge will be posting new Waku v1 envelopes, which requires doing the PoW nonce calculation.

This could be a DoS attack vector, as the PoW calculation will make it more expensive to post the message compared to the original publishing on the Waku v2 network. Low PoW setting will lower this problem, but it is likely that it is still more expensive.

For this reason, bridges SHOULD probably be run independently of other nodes, so that a bridge that gets overwhelmed does not disrupt regular Waku v2 to v2 traffic.

Bridging functionality SHOULD also be carefully implemented so that messages do not bounce back and forth between the two networks. The bridge SHOULD properly track messages with a seen filter so that no amplification can be achieved here.

Copyright

Copyright and related rights waived via CC0.