Worldcoin Sign-up Sequencer

Sign-up Sequencer does sequencing of data (identities) that are committed in a batch to an Ethereum Smart Contract.

Table of Contents

1. Introduction
2. Getting Started
3. Tests
4. Contributing

Introduction

Sequencer has 6 API routes.

1. /insertIdentity - Accepts identity commitment hash as input which gets added in queue for processing. Identities go through three tasks.
   1. Insertion: In the initial stage, the identities are placed into the Sequencer's database. The database is polled every few seconds and added to insertion task.
   2. Processing: The processing of identities, where current batching tree is taken and processed so we end up with pre root (the root of tree before proofs are generated), post root, start index and identity commitments (with their proofs). All of those get sent to a prover for proof generation. The identities transaction is then mined, with aforementioned fields and pending identities are sent to task to be mined on-chain.
   3. Mining: The transaction ID from processing task gets mined and Sequencer database gets updated accordingly. Now with blockchain and database being in sync, the mined tree gets updated as well.
2. /inclusionProof - Takes the identity commitment hash, and checks for any errors that might have occurred in the insert identity steps. Then leaf index is fetched from the database, corresponding to the identity hash provided, and then we check if the identity is indeed in the tree. The inclusion proof is then returned to the API caller.
3. /deleteIdentity - Takes an identity commitment hash, ensures that it exists and hasn't been deleted yet. This identity is then scheduled for deletion.
4. /recoverIdentity - Takes two identity commitment hashes. The first must exist and will be scheduled for deletion and the other will be inserted as a replacement after the first identity has been deleted and a set amount of time (depends on configuration parameters) has passed.
5. /verifySemaphoreProof - This call takes root, signal hash, nullifier hash, external nullifier hash and a proof. The proving key is fetched based on the depth index, and verification key as well. The list of prime fields is created based on request input mentioned before, and then we proceed to verify the proof. Sequencer uses groth16 zk-SNARK implementation. The API call returns the proof as a response.
6. /addBatchSize - Adds a prover with specific batch size to a list of provers.
7. /removeBatchSize - Removes the prover based on batch size.
8. /listBatchSizes - Lists all provers that are added to the Sequencer.

Getting Started

(Local development)

Install Protobuf compiler

Os	Command
MacOs	brew install protobuf
Ubuntu/Debian	sudo apt-get install -y protobuf-compiler

Install Docker - Docker is used to setup the database for testing

Fetch the postgres docker image before running tests.

docker pull postgres

Worldcoin id contracts

Worldcoin id contracts are ethereum smart contracts that are used by the sequencer

Clone worldcoin id contracts and execute make build && npm install

You will need a local ethereum chain, like geth or ganache. Start up your local ethereum network and generate an account. Go to your worldcoin id contracts repo folder and do make deploy. Follow the steps provided by the script. Make sure you use a private key from your local ethereum network account. !! Make a note of all the addresses generated by the script !!

Semaphore-mtb

Semaphore-mtb is a service for batch processing of Merkle tree updates.

Clone semaphore-mtb and execute go build . (you will need a golang compiler)

Go build will create an executable named gnark-mbu. If you went through the worldcoin id contracts deploy script, you will have a generated keys file that is used by semaphore-mtb.

./gnark-mbu start --keys-file path/to/world-id-contracts/mtb/keys

Database

docker run --rm -ti -p 5432:5432 -e POSTGRES_PASSWORD=password postgres

Now you are ready to start up sequencer service!

TREE_DEPTH=*your tree depth (eg. 16)* cargo run -- --batch-size *batch size for semaphore-mtb (eg. 3)* --batch-timeout-seconds 10 --database postgres://postgres:password@0.0.0.0:5432 --identity-manager-address *address from worldcoin id contracts identity manager*
--signing-key *private key you used to deploy smart contracts*

Tests

Lint, build, test

First ensure you have the docker daemon up and running, then:

cargo fmt && cargo clippy --all-targets && cargo build --all-targets && cargo test --all-targets

Contributing

We welcome your pull requests! But also consider the following:

1. Fork this repo from main branch.
2. If you added code that should be tested, please add tests.
3. If you changed the API routes, please update this readme in your PR.
4. Ensure that CI tests suite passes (lints as well).
5. If you added dependencies, make sure you add exemptions for cargo vet

When you submit code changes, your submissions are understood to be under the same MIT License that covers the project. Feel free to contact the maintainers if that's a concern.

Report bugs using github issues.