Waku 0: Replace Whisper EIP627 with the de facto Whisper fork Status uses

[oskarth]

Problem

Currently apps such as Status use a forked version of EIP627 that isn't properly documented. This makes it difficult to write additional implementations, such as Nim, since a lot of behavior isn't documented.

Additionally, people often confuse "Whisper" with "our (Status) fork of Whisper" which is undesirable terms of being explicit about what requirements we have and what guarantees we provide.

Finally, this is a stepping stone to address bandwidth consumption in a proper Waku mode, which will happen in Waku v1.

Acceptance criteria

• EIP627 replaced with a forked, spec with rationale and replacing Whisper with Waku
• Describe RLPx subprotocol and version numbers
• Waku/0 spec in uniform format with other specs
• Reviewed by swarm and merged to specs.vac.dev

The below are optional for a initial release, and can be addressed in e.g. 0.1 spec release (still Waku version 0). At a minimum, the below should be better understood and captured:

• Describe backwards compatibility with Whisper v6 / v1 (Waku - Ensure network compatibility between Status v1 clients (Whisper v6) and Waku 0 research#14) - sketch in spec

Not solved, but issues created:

• Describes existing mailserver usage, see Waku 0: Mail Servers #36
• Describe existing light client usage, see Document Waku existing light node behavior #29
• Describe current implementation status in terms of capabilities (i.e. geth vs nimbus wrt light node, etc) Implementation matrix for Whisper/Waku clients status-im/specs#63
• Include privacy, scalability and DDoS considerations (see Waku 0: Include privacy, scalability and DDoS considerations #39)
• Describe existing rate limiting Waku 0: Describe existing rate limiting #40
• Describe forward compatibility with waku/1 Waku 0: Document forward compatibility #41

Details

See:

• https://eips.ethereum.org/EIPS/eip-627
• https://github.com/status-im/specs/blob/master/status-whisper-usage-spec.md
• https://github.com/status-im/specs/blob/master/status-whisper-mailserver-spec.md

As well as implementations in status-im/whisper and status-im/nim-eth

Possible Solutions

See above for acceptance criteria.

Notes

[oskarth]

Few notes/additions:

1. Version 0 of RLPx subprotocol crashes, unclear if this is spec or impl issue. We might just make waku/1 the original waku/0 idea and go from there (eth is on version 63!), see Setting RLPx subprotocol version to 0 crashes status-im/nim-eth#119

2. Subprotocol isn't describe in EIP627, i.e. shh/6 isn't documented like in e.g. https://github.com/ethereum/devp2p/blob/master/caps/eth.md

3. Subprotocols in nim-eth appears to be limited to three characters, the devp2p/RLPx spec just says "short ascii name" from what I can tell, unclear if spec or impl issue. For now I call this wkk, see Setting RLPx subprotocol version to 0 crashes status-im/nim-eth#119

FYI @kdeme

[oskarth]

Subtask describe mailserver usage partially blocked by status-im/specs#55

[oskarth]

Updated issue with latest state and links etc. Please see #28 for changes

[oskarth]

All current TODOs in #28 text should be pulled out of there and put in Github issue, e.g. one master enhancement issue and/or small specific issues for furher discussion.

[oskarth]

Initial cut done for Waku 0, closing this.

@decanus will create follow up issue with inlined TODOs and continue improving it (mailserver use, abnf, definitions etc)