celestia-core

celestia-core is a fork of cometbft/cometbft, an implementation of the Tendermint protocol, with the following changes:

1. Modifications to how DataHash in the block header is determined. In CometBFT, DataHash is based on the transactions included in a block. In Celestia, block data (including transactions) are erasure coded into a data square to enable data availability sampling. In order for the header to contain a commitment to this data square, DataHash was modified to be the Merkle root of the row and column roots of the erasure coded data square. See ADR 008 for the motivation or celestia-app/pkg/da/data_availability_header.go for the implementation. The DataHash is computed by the application in PrepareProposal and returned to CometBFT as the second to last transaction. The last transaction is the big endian encoded uint64 of the square size. The SquareSize is included in the modified Data struct that is gossiped to peers. Similarly CometBFT passes the DataHash as the second to last tx and the SquareSize as the final transaction in ProcessProposal.
2. A content-addressable transaction (CAT) pool was implemented using the Mempool interface to reduce the duplication and thus bandwidth of peers sending transactions to one another. The specification can be found here.

See ./docs/celestia-architecture for architecture decision records (ADRs) on Celestia modifications.

Diagram

                ^  +-------------------------------+  ^
                |  |                               |  |
                |  |  State-machine = Application  |  |
                |  |                               |  |   celestia-app (built with Cosmos SDK)
                |  |            ^      +           |  |
                |  +----------- | ABCI | ----------+  v
Celestia        |  |            +      v           |  ^
validator or    |  |                               |  |
full consensus  |  |           Consensus           |  |
node            |  |                               |  |
                |  +-------------------------------+  |   celestia-core (fork of CometBFT)
                |  |                               |  |
                |  |           Networking          |  |
                |  |                               |  |
                v  +-------------------------------+  v

Install

See https://github.com/celestiaorg/celestia-app#install

Usage

See https://github.com/celestiaorg/celestia-app#usage

Contributing

This repo intends on preserving the minimal possible diff with cometbft/cometbft to make fetching upstream changes easy. If the proposed contribution is

• specific to Celestia: consider if celestia-app is a better target
• not specific to Celestia: consider making the contribution upstream in CometBFT

1. Install Go 1.20+
2. Fork this repo
3. Clone your fork
4. Find an issue to work on (see good first issues)
5. Work on a change in a branch on your fork
6. When your change is ready, push your branch and create a PR that targets this repo

Helpful Commands

# Build a new CometBFT binary and output to build/comet
make build

# Install CometBFT binary
make install

# Run tests
make test

# If you modified any protobuf definitions in a `*.proto` file then
# you may need to lint, format, and generate updated `*.pb.go` files
make proto-lint
make proto-format
make proto-gen

Branches

The canonical branches in this repo are based on CometBFT releases. For example: v0.34.x-celestia is based on the CometBFT v0.34.x release branch and contains Celestia-specific changes.

Usually PRs should target the main branch. After the PR merges to main, if the PR contained non-breaking changes, a maintainer may cherry-pick it to an existing release branch (e.g. v0.34.x-celestia) and cut a new release.

Versioning

Releases are formatted: v<CELESTIA_CORE_VERSION>-tm-v<TENDERMINT_CORE_VERSION> For example: v1.4.0-tm-v0.34.20 is celestia-core version 1.4.0 based on CometBFT 0.34.20. CELESTIA_CORE_VERSION strives to adhere to Semantic Versioning.

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