SSZ implementations list

[protolambda]

trafficstars

A non-exhaustive list of SSZ implementations. Not officially endorsed, but maintained by client teams and other members of the ethereum community. Comment in this issue if you like to add/update an entry.

Maintained here to avoid continuous changes to the spec (and not delay table updates till spec release).

Language	Project	Maintainer	License	Status	Features / Notes	Implementation
C++	Prysm	Offchain Labs	Apache-2.0	Active	No dynamic dispatching, minimal memory alloc.	OffchainLabs/sszpp
Dafny	Eth2 spec/verif. with Dafny	ConsenSys Software And Ethereum Foundation (grant)	Apache-2.0	Active	Formal spec., correctness proofs	ConsenSys/eth2.0-dafny
Go	ZRNT	Diederik Loerakker (@protolambda)	MIT	Active	Generic, caching, datasharing	protolambda/ztyp
Go	Prysm	Ferran Borreguero (@ferranbt)	MIT	Active	Code-gen, fast	ferranbt/fastssz
Go	SSZ-15 / Go-ethereum	Péter Szilágyi (@karalabe)	BSD 3-Clause	Active	Code-gen, fast, 0-alloc	karalabe/ssz
Go	EF-devops / pk910	@pk910	Apache-2.0	Active	Dynamic using type reflection	pk910/dynamic-ssz
Java	Teku	Consensys/PegaSys Eng.	Apache-2.0	Active	Caching, datasharing	PegaSysEng/teku/ssz
Nim	Nimbus	Status	MIT and Apache-2.0	Active	In-place decode, Caching	status-im/nim-ssz-serialization
Python	Trinity	Ethereum Foundation	MIT	Active	Pyrsistent, partial caching	ethereum/py-ssz
Python	Pyspec / Eth2.py	Diederik Loerakker (@protolambda)	MIT	Active	Datasharing, caching, streaming	protolambda/remerkleable
Rust	-	Alex Stokes (@ralexstokes)	MIT	Active	Built for light-client usage	ralexstokes/ssz-rs
Rust	Lighthouse	Sigma Prime	Apache-2.0	Active	Partial caching, fast	sigp/ethereum_ssz
Typescript	Lodestar	Chainsafe Systems	Apache-2.0	Active	Both Tree & structural, caching	ChainSafe/ssz
Typescript	Micro-eth-signer	Paul Miller (@paulmillr)	MIT	Active	Minimalist	paulmillr/micro-eth-signer/src/ssz.ts
Zig	-	Guillaume Ballet (@gballet)	Unlicense	Active	Zig	gballet/ssz.zig
C#	-	@hexafluoride	MIT	Active	Experimental, serialization only	hexafluoride/SszSharp
C#	-	Nethermind	?	Early draft	Code-gen, draft	NethermindEth/ssz-codegen
C++	Mammon	Potuz	GPL-3.0	Paused	Optimized hash function	potuz/mammon
Go	Prysm	Prysmatic Labs	MIT	Deprecated	Generic, reflection, known bugs	prysmaticlabs/go-ssz
Go	ZRNT	Diederik Loerakker (@protolambda)	MIT	Deprecated	Unsafe Go, fast, streaming	protolambda/zssz
Go	Go-ethereum	@rjl493456442	BSD 3-Clause	Discontinued	Code-gen, encoding-only	rjl493456442/sszgen
Java	Harmony	Harmony	Apache-2.0	Deprecated	Partially merged into Teku	harmony-dev/beacon-chain-java/ssz
TypeScript	Lodestar	ChainSafe Systems	Apache-2.0	Archived	See new Lodestar SSZ	ChainSafe/ssz-js
C#	Cortex	Sly Gryphon (@sgryphon)	LGPL-v3.0	Discontinued	Experimental	sgryphon/cortex-ssz
Rust	Shasper	ParityTech	GPL-3.0	Discontinued	No updates	paritytech/shasper/ssz
Swift	Yeeth	Dean Eigenmann (@decanus, @yeeth)	MIT	Discontinued	Incomplete	yeeth/SimpleSerialize.swift
Java	Cava	ConsenSys	Apache-2.0	Discontinued	Outdated, incomplete	ConsenSys/cava/ssz

[franck44]

@protolambda Thanks for starting this list. BTW what is the order chosen for the list? It does not seem be sorted against languages, or alphabetical ... or license. And what is the difference between archived/deprecated/discontinued?

There is a formal specification and implementations of the SSZ functions in Dafny here. The functional style of the implementations does not prescribe any particular language, but rather identifies the pre/post-condutions of each function. The Dafny implementations are executable, can be translated into C#, Go, Java. More importantly the code is proved correct against some desirable properties, e.g., deserialise(serialise(x)) == x (proof here) and injectiveness of serialise (proof here).

There is also an SSZ wiki. (WIP)

Entry proposal: Language: Dafny Project: Specification and Verification of Eth2.0 in Dafny Maintainer: ConsenSys Software And Ethereum Foundation (grant) License: Apache-2.0 Status: Active Features: Formal specification of each function with pre-post-conditions, correctness proofs Link: link to repo

[protolambda]

@franck44 no particular order, but roughly ordered by "status" (active being the highest ranking), then grouped by "language" (alphabetical), and then any order how I happened to build the list. The deprecated/discontinued etc. libraries are at the bottom so they are not as noisy. Happy to re-order if you've a suggestion.

My interpretation here: archived: not maintained, only there to keep the code public. Not recommended to use. May be replaced with something else. GitHub has a nice archive function, which makes a repo read-only. deprecated: code that mostly works, but is considered legacy and not recommended for production. discontinued: code that mostly works, but end-of-life without replacement, nor any archival guaranteed.

In the end most users should just pick an active implementation, of which there are plenty options.

Dafny entry proposal sounds good, will add it. Will need to summarize the "Features" to fit in the table though. Hope I don't butcher it.

[gballet]

@protolambda could you please add gballet/ssz.zig, the ziglang implementation that I am maintaining? No project in particular (or "geth" if you must have one) and the license is "The Unlicense".

[hexafluoride]

Proposing SszSharp be added to this list, as the other C# implementations are quite incomplete compared to mine. Currently, serialization and deserialization is supported well enough that it can roundtrip a BeaconState, and merkleization support is planned. Licensed under MIT.

[amirkhan7javi]

Thanks for the cooperation