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# Ethereum Proof-of-Stake Consensus Specifications
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[](https://discord.gg/qGpsxSA) [](https://gitter.im/ethereum/sharding?utm_source=badge& utm_medium=badge& utm_campaign=pr-badge& utm_content=badge)
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To learn more about proof-of-stake and sharding, see the [PoS FAQ ](https://eth.wiki/en/concepts/proof-of-stake-faqs ), [sharding FAQ ](https://eth.wiki/sharding/Sharding-FAQs ) and the [research compendium ](https://notes.ethereum.org/s/H1PGqDhpm ).
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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.
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## Specs
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[](https://github.com/ethereum/eth2.0-specs/releases/) [](https://badge.fury.io/py/eth2spec)
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Core specifications for Ethereum proof-of-stake clients can be found in [specs ](specs/ ). These are divided into features.
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Features are researched and developed in parallel, and then consolidated into sequential upgrades when ready.
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The current features are:
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### Phase 0
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* [The Beacon Chain ](specs/phase0/beacon-chain.md )
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* [Beacon Chain Fork Choice ](specs/phase0/fork-choice.md )
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* [Deposit Contract ](specs/phase0/deposit-contract.md )
* [Honest Validator ](specs/phase0/validator.md )
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* [P2P Networking ](specs/phase0/p2p-interface.md )
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* [Weak Subjectivity ](specs/phase0/weak-subjectivity.md )
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### Altair
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* [Beacon chain changes ](specs/altair/beacon-chain.md )
* [Altair fork ](specs/altair/fork.md )
* [Light client sync protocol ](specs/altair/sync-protocol.md )
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* [Honest Validator guide changes ](specs/altair/validator.md )
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* [P2P Networking ](specs/altair/p2p-interface.md )
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### Merge
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The merge is still actively in development. The exact specification has not been formally accepted as final and details are still subject to change.
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* Background material:
* An [ethresear.ch ](https://ethresear.ch ) post [describing the basic mechanism ](https://ethresear.ch/t/the-eth1-eth2-transition/6265 )
* [ethereum.org ](https://ethereum.org ) high-level description of the merge [here ](https://ethereum.org/en/eth2/docking/ )
* Specifications:
* [Beacon Chain changes ](specs/merge/beacon-chain.md )
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* [Merge fork ](specs/merge/fork.md )
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* [Fork Choice changes ](specs/merge/fork-choice.md )
* [Validator additions ](specs/merge/validator.md )
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* [Client settings ](specs/merge/client_settings.md )
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### Sharding
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Sharding follows the merge, and is divided into three parts:
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* Sharding base functionality - In early engineering phase
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* [Beacon Chain changes ](specs/sharding/beacon-chain.md )
* [P2P Network changes ](specs/sharding/p2p-interface.md )
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* Custody Game - Ready, dependent on sharding
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* [Beacon Chain changes ](specs/custody_game/beacon-chain.md )
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* [Validator custody work ](specs/custody_game/validator.md )
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* Data Availability Sampling - In active R& D
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* Technical details [here ](https://hackmd.io/@HWeNw8hNRimMm2m2GH56Cw/B1YJPGkpD ).
* [Core types and functions ](specs/das/das-core.md )
* [P2P Networking ](specs/das/p2p-interface.md )
* [Fork Choice ](specs/das/fork-choice.md )
* [Sampling process ](specs/das/sampling.md )
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### Accompanying documents can be found in [specs](specs) and include:
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* [SimpleSerialize (SSZ) spec ](ssz/simple-serialize.md )
* [Merkle proof formats ](ssz/merkle-proofs.md )
* [General test format ](tests/formats/README.md )
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## Additional specifications for client implementers
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Additional specifications and standards outside of requisite client functionality can be found in the following repos:
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* [Beacon APIs ](https://github.com/ethereum/beacon-apis )
* [Beacon Metrics ](https://github.com/ethereum/beacon-metrics/ )
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## Design goals
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The following are the broad design goals for the Ethereum proof-of-stake consensus specifications:
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* to minimize complexity, even at the cost of some losses in efficiency
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* to remain live through major network partitions and when very large portions of nodes go offline
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* 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)
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## Useful external resources
* [Design Rationale ](https://notes.ethereum.org/s/rkhCgQteN# )
* [Phase 0 Onboarding Document ](https://notes.ethereum.org/s/Bkn3zpwxB )
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* [Combining GHOST and Casper paper ](https://arxiv.org/abs/2003.03052 )
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## For spec contributors
Documentation on the different components used during spec writing can be found here:
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* [YAML Test Generators ](tests/generators/README.md )
* [Executable Python Spec, with Py-tests ](tests/core/pyspec/README.md )
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## Consensus spec tests
Conformance tests built from the executable python spec are available in the [Ethereum Proof-of-Stake Consensus Spec Tests ](https://github.com/ethereum/consensus-spec-tests ) repo. Compressed tarballs are available in [releases ](https://github.com/ethereum/consensus-spec-tests/releases ).
