BigBrother Specs

Big Brother can't watch you!

Table of Contents

• Abstract
• Motivation
• Terms
• Design Goals
• System Design / Architecture
  • SOLID
• Phases
  • Phase 0
  • Phase 1
  • Phase 2
  • Phase 3
  • Phase 4
  • Phase 5
• Footnotes

Abstract

BigBrother defines a family of protocols that when combined create a decentralized peer-to-peer messaging stack. BigBrother should enable various messaging types, in order to be called a messaging stack.

The family of protocols SHOULD be flexible enough to allow various use case implementations not limited to that being defined by the entire family. The BigBrother protocol itself defines mainly the way the family of protocols interact with one another allowing for customizability on each layer.

Motivation

TODO: TALK ABOUT SHORTCOMINGS OF WHISPER

Terms

Term	Definition
Stack	Defines the entire family of protocols, how they interact and what goals are achieved.
Protocol	Defines a single layer in the stack along with its endpoints used for communication with various other protocols in the stack.

Design Goals

1. Anonymity - sender / receiver MUST remain anonymous.
2. Unlinkability - It should not be identifiable which parties are talking to eachother.
3. Scalable - @TODO
4. Incentivized - @TODO
5. Decentralized - @TODO
6. Resistant - @TODO
7. Inclusive - Protocols within the stack should be designed to work on resource restricted devices, this allows for a higher participation making the entire BigBrother protocol more usable and reliable.

System Design / Architecture

The protocols summarized by BigBrother all follow a standard of architectural design principles with the goal of keeping each component noncomplicated. We architect a stack where each protocol interacts holistically, without the desire to create unnecessary complexity. Each protocol included in the stack should be simplistic enough to allow for multiple implementations creating client diversity, allowing us to ensure that the entire stack is unambiguous¹.

SOLID

Throughout the design of the stack we follow the SOLID design principles, redefining them slightly so they make sense in the context of protocols.

• Single Responsibility principle: Each protocol in the family should only have a single responsibility.
• Open/closed principle: @TODO
• Liskov substitution principle: @TODO
• Interface segregation principle: @TODO
• Dependency inversion principle: @TODO

Stack

The below table shows the intended layers of the network from the highest to the lowest.

Layer / Protocol	Purpose	Example
Sync Clients	End user functionality	1:1, group chat, tribute, ...
Data Sync	Syncing data/state	Bramble Sync Protocol (ish)
Secure Transport	Confidentiality, PFS, etc	Double Ratchet
Transport Privacy	Metadata protection	Mixnet?
P2P Overlay	Overlay routing, NAT traversal	libp2p?

Phases

Inspired by the ETH 2.0 implementation process, we have decided to roll out BigBrother in multiple phases. The phases can mostly be linked to various layers in the stack. Some of these phases are sometimes more loosely coupled than ETH 2.0 components meaning they can be done in parallel as only the communication API is relevant.

Phase 0 - XKEYSCORE (Data Sync)

Phase 1 - BULLRUN (Transport Privacy Layer)

• Mixnet
• PSS
• Bluetooth local network
• Sneakernet

Phase 2 - STONEGHOST (P2P Overlay)

Phase 3 - CREDIBLE (Secure Transport)

• Message Layer Security (MLS)

Phase 4 - COINTELPRO / JTRIG OPS (Data Sync Clients)

Phase 5 - NATIVEFLORA / TAO OPS (Trust Establishment)

Footnotes

• [1] http://ethdocs.org/en/latest/ethereum-clients/choosing-a-client.html