Tendermint X

Implementation of zero-knowledge proof circuits for Tendermint.

Overview

Tendermint X's core contract is TendermintX, which stores the headers of Tendermint blocks. Users can query a TendermintX contract for the header of a specific block height, or for the latest header.

There are two entrypoints to a TendermintX contract, step and skip.

skip

skip is used to jump from the current header to a non-consecutive header.

For example, let's say block N has already been proven in the light client, and we want to prove block N+10. We can skip from block N to block N+10 if 1) the validators who have signed the commit for block N+10 comprise > 1/3 of the voting power on block N and 2) validators comprimising > 2/3 of the voting power on block N+10 have signed the commit for block N+10.

The methodology for doing so is described in the section 6 of A Tendermint Light Client.

step

step is used to sequentially verify the next header after the current header.

This is rarely used, as step will only be invoked when the validator set changes by more than 2/3 in a single block.

Deploy Tendermint X for a chain

Tendermint X Circuits

1. Fork this repository: https://github.com/succinctlabs/tendermintx

2. Update the VALIDATOR_SET_SIZE_MAX to match that of your Tendermint chain in circuits/consts.rs. Push the changes to your fork.

3. Add a new circuit config for your Tendermint chain in circuits/config.rs. Replace celestia with the chain ID (network name) of your Tendermint chain.

   /// Example chain config for Celestia
   pub const CELESTIA_CHAIN_ID_BYTES: &[u8] = b"celestia";
   pub const CELESTIA_CHAIN_ID_SIZE_BYTES: usize = CELESTIA_CHAIN_ID_BYTES.len();
   #[derive(Debug, Clone, PartialEq)]
   pub struct CelestiaConfig;
   impl TendermintConfig<CELESTIA_CHAIN_ID_SIZE_BYTES> for CelestiaConfig {
       const CHAIN_ID_BYTES: &'static [u8] = CELESTIA_CHAIN_ID_BYTES;
       const SKIP_MAX: usize = SKIP_MAX;
   }   

4. Update bin/skip.rs and bin/step.rs to use your new chain config instead of CelestiaConfig.

Set up circuits on the Succinct Platform

1. Go to the Succinct Platform.

2. Sign up for an account on the platform.

3. Create a new project on the Succinct Platform by importing your fork of tendermintx.

4. In your project on the platform, go to Releases. Create two new releases, one for step and one for skip. Use the main branch and set the entrypoint accordingly.

5. In your project on the platform, go to Settings. Set TENDERMINT_RPC_URL in Environment Variables. This should be a valid full node RPC for your Tendermint chain.

6. Once the releases are completed building, go to Deployments to deploy the verifiers for step and skip.

Deploy Tendermint X Contracts

1. Open the code for your fork of tendermintx again.

2. Update contracts/.env accoridng to contracts/.env.example. Note: The genesis parameters are typically sourced from a recent header from your Tendermint chain.

3. Deploy your TendermintX contract and initialize it with your function ID & genesis parameters using the commands below.

forge install

forge script script/Deploy.s.sol --rpc-url $ETHEREUM_RPC_URL --private-key $PRIVATE_KEY --etherscan-api-key $ETHERSCAN_API_KEY --verify TendermintX --broadcast

Run the light client operator

1. Update .env according to .env.example.

   1. Get SUCCINCT_API_KEY from your Succinct Platform user/project settings.
   2. SUCCINCT_RPC_URL=https://alpha.succinct.xyz/api

2. Run TendermintX script to update the light client continuously (currently set to update once every 4 hours).

cargo run --bin tendermintx --release

3. Now, go the platform to monitor the status of your proofs. Generating a Tendermint LC proof takes anywhere from 4-10 minutes, depending on your validator set size.

Misc

Tendermint RPC's

To find a list of RPC's for most Tendermint chains, check out this page created by @deving_zone.

Block Protocol Version

Tendermint X is configured to work with CometBFT block protocol version 11. If this changes in the future, the Tendermint X circuits might need to be updated.

Audit

Informal Audit

• Tendermint X has been audited by Informal Systems. The audit report can be found here.