Ethereum Proof-of-Stake Consensus Specifications

To learn more about proof-of-stake and sharding, see the PoS FAQ, sharding FAQ and the research compendium.

This repository hosts the current Ethereum proof-of-stake specifications. Discussions about design rationale and proposed changes can be brought up and discussed as issues. Solidified, agreed-upon changes to the spec can be made through pull requests.

Specs

Core specifications for Ethereum proof-of-stake clients can be found in specs. These are divided into features. Features are researched and developed in parallel, and then consolidated into sequential upgrades when ready.

Stable Specifications

Seq.	Code Name	Fork Epoch	Specs
0	Phase0	0	Core The beacon chain Deposit contract Beacon chain fork choice Additions Honest validator guide P2P networking Weak subjectivity
1	Altair	74240	Core Beacon chain changes Altair fork Additions Light client sync protocol Honest validator guide changes P2P networking
2	Bellatrix ("The Merge")	TBD	Core Beacon Chain changes Bellatrix fork Fork choice changes Additions Honest validator guide changes P2P networking

In-development Specifications

Code Name or Topic	Specs	Notes
Capella (tentative)	Core Beacon chain changes Capella fork Additions Validator additions
EIP4844 (tentative)	Core Beacon Chain changes EIP-4844 fork Additions Honest validator guide changes P2P networking
Sharding (outdated)	Core Beacon Chain changes Additions P2P networking
Custody Game (outdated)	Core Beacon Chain changes Additions Honest validator guide changes	Dependent on sharding
Data Availability Sampling (outdated)	Core Core types and functions Fork choice changes Additions P2P Networking Sampling process	Dependent on sharding Technical explainer

Accompanying documents can be found in specs and include:

• SimpleSerialize (SSZ) spec
• Merkle proof formats
• General test format

Additional specifications for client implementers

Additional specifications and standards outside of requisite client functionality can be found in the following repos:

• Beacon APIs
• Beacon Metrics

Design goals

The following are the broad design goals for the Ethereum proof-of-stake consensus specifications:

• to minimize complexity, even at the cost of some losses in efficiency
• to remain live through major network partitions and when very large portions of nodes go offline
• to select all components such that they are either quantum secure or can be easily swapped out for quantum secure counterparts when available
• to utilize crypto and design techniques that allow for a large participation of validators in total and per unit time
• to allow for a typical consumer laptop with O(C) resources to process/validate O(1) shards (including any system level validation such as the beacon chain)

Useful external resources

• Design Rationale
• Phase 0 Onboarding Document
• Combining GHOST and Casper paper

For spec contributors

Documentation on the different components used during spec writing can be found here:

• YAML Test Generators
• Executable Python Spec, with Py-tests

Consensus spec tests

Conformance tests built from the executable python spec are available in the Ethereum Proof-of-Stake Consensus Spec Tests repo. Compressed tarballs are available in releases.