H2 Chain

In order to embrace the existing popular community and advanced technology, H2 chain will bring huge benefits by staying compatible with all the existing smart contracts on Ethereum and Ethereum tooling. And to achieve that, the easiest solution is to develop based on go-ethereum fork, as we respect the great work of Ethereum very much.

But from that baseline of EVM compatible, H2 Chain introduces a system of 21 validators with Proof of Staked Authority (PoSA) consensus that can support short block time and lower fees. The most bonded validator candidates of staking will become validators and produce blocks. The double-sign detection and other slashing logic guarantee security, stability, and chain finality.

The H2 Chain will be:

• A self-sovereign blockchain: Provides security and safety with elected validators.
• EVM-compatible: Supports all the existing Ethereum tooling along with faster finality and cheaper transaction fees.
• Distributed with on-chain governance: Proof of Staked Authority brings in decentralization and community participants. As the native token, H2will serve as both the gas of smart contract execution and tokens for staking.

More details in White Paper.

Release Types

There are three types of release, each with a clear purpose and version scheme:

• 1.Stable Release: production-ready builds for the vast majority of users. Format: v<Major>.<Minor>.<Patch>, example: v1.0.0.
• 2.Feature Release: early access to a single feature without affecting the core product. Format: v<Major>.<Minor>.<Patch>-feature-<FeatureName>, example: v1.0.0-feature-SI.
• 3.Preview Release: bleeding-edge builds for users who want the latest code. Format: v<Major>.<Minor>.<Patch>-<Meta>, Meta values indicate maturity: alpha (experimental), beta (largely complete), rc (release candidate), example: v1.0.0-alpha.

Key features

Proof of Staked Authority

Although Proof-of-Work (PoW) has been approved as a practical mechanism to implement a decentralized network, it is not friendly to the environment and also requires a large size of participants to maintain the security.

Proof-of-Authority(PoA) provides some defense to 51% attack, with improved efficiency and tolerance to certain levels of Byzantine players (malicious or hacked). Meanwhile, the PoA protocol is most criticized for being not as decentralized as PoW, as the validators, i.e. the nodes that take turns to produce blocks, have all the authorities and are prone to corruption and security attacks.

Other blockchains, such as EOS and Cosmos both, introduce different types of Deputy Proof of Stake (DPoS) to allow the token holders to vote and elect the validator set. It increases the decentralization and favors community governance.

To combine DPoS and PoA for consensus, H2 Chain implement a novel consensus engine called Parlia that:

1. Blocks are produced by a limited set of validators.
2. Validators take turns to produce blocks in a PoA manner, similar to Ethereum's Clique consensus engine.
3. Validator set are elected in and out based on a staking based governance on H2 Chain.
4. Parlia consensus engine will interact with a set of system contracts to achieve liveness slash, revenue distributing and validator set renewing func.

Native Token

H2 will run on H2 Chain in the same way as ETH runs on Ethereum so that it remains as native token for H2. This means, H2 will be used to:

1. pay gas to deploy or invoke Smart Contract on H2

Building the source

Many of the below are the same as or similar to go-ethereum.

For prerequisites and detailed build instructions please read the Installation Instructions.

Building geth requires both a Go (version 1.24 or later) and a C compiler (GCC 5 or higher). You can install them using your favourite package manager. Once the dependencies are installed, run

make geth

or, to build the full suite of utilities:

make all

If you get such error when running the node with self built binary:

Caught SIGILL in blst_cgo_init, consult <blst>/bindinds/go/README.md.

please try to add the following environment variables and build again:

export CGO_CFLAGS="-O -D__BLST_PORTABLE__"
export CGO_CFLAGS_ALLOW="-O -D__BLST_PORTABLE__"

Executables

The h2 project comes with several wrappers/executables found in the cmd directory.

Command	Description
geth	Main H2 Chain client binary. It is the entry point into the H2 network (main-, test- or private net), capable of running as a full node (default), archive node (retaining all historical state) or a light node (retrieving data live). It has the same and more RPC and other interface as go-ethereum and can be used by other processes as a gateway into the H2 network via JSON RPC endpoints exposed on top of HTTP, WebSocket and/or IPC transports. geth --help and the CLI page for command line options.
clef	Stand-alone signing tool, which can be used as a backend signer for geth.
devp2p	Utilities to interact with nodes on the networking layer, without running a full blockchain.
abigen	Source code generator to convert Ethereum contract definitions into easy to use, compile-time type-safe Go packages. It operates on plain Ethereum contract ABIs with expanded functionality if the contract bytecode is also available. However, it also accepts Solidity source files, making development much more streamlined. Please see our Native DApps page for details.
bootnode	Stripped down version of our Ethereum client implementation that only takes part in the network node discovery protocol, but does not run any of the higher level application protocols. It can be used as a lightweight bootstrap node to aid in finding peers in private networks.
evm	Developer utility version of the EVM (Ethereum Virtual Machine) that is capable of running bytecode snippets within a configurable environment and execution mode. Its purpose is to allow isolated, fine-grained debugging of EVM opcodes (e.g. evm --code 60ff60ff --debug run).
rlpdump	Developer utility tool to convert binary RLP (Recursive Length Prefix) dumps (data encoding used by the Ethereum protocol both network as well as consensus wise) to user-friendlier hierarchical representation (e.g. rlpdump --hex CE0183FFFFFFC4C304050583616263).

Running geth

Going through all the possible command line flags is out of scope here (please consult our CLI Wiki page), but we've enumerated a few common parameter combos to get you up to speed quickly on how you can run your own geth instance.

Hardware Requirements

The hardware must meet certain requirements to run a full node on mainnet:

• VPS running recent versions of Mac OS X, Linux, or Windows.
• IMPORTANT 3 TB(Dec 2023) of free disk space, solid-state drive(SSD), gp3, 8k IOPS, 500 MB/S throughput, read latency <1ms. (if node is started with snap sync, it will need NVMe SSD)
• 16 cores of CPU and 64 GB of memory (RAM)
• Suggest m5zn.6xlarge or r7iz.4xlarge instance type on AWS, c2-standard-16 on Google cloud.
• A broadband Internet connection with upload/download speeds of 5 MB/S

The requirement for testnet:

• VPS running recent versions of Mac OS X, Linux, or Windows.
• 500G of storage for testnet.
• 4 cores of CPU and 16 gigabytes of memory (RAM).

Steps to Run a Fullnode

1. Download the pre-build binaries

# Linux
wget $(curl -s https://api.github.com/repos/h2-chain/h2/releases/latest |grep browser_ |grep geth_linux |cut -d\" -f4)
mv geth_linux geth
chmod -v u+x geth

# MacOS
wget $(curl -s https://api.github.com/repos/h2-chain/h2/releases/latest |grep browser_ |grep geth_mac |cut -d\" -f4)
mv geth_macos geth
chmod -v u+x geth

2. Download the config files

//== mainnet
wget $(curl -s https://api.github.com/repos/h2-chain/h2/releases/latest |grep browser_ |grep mainnet |cut -d\" -f4)
unzip mainnet.zip

//== testnet
wget $(curl -s https://api.github.com/repos/h2-chain/h2/releases/latest |grep browser_ |grep testnet |cut -d\" -f4)
unzip testnet.zip

3. Download snapshot

Download latest chaindata snapshot from here. Follow the guide to structure your files.

4. Start a full node

## It will run with Path-Base Storage Scheme by default and enable inline state prune, keeping the latest 90000 blocks' history state.
./geth --config ./config.toml --datadir ./node  --cache 8000 --rpc.allow-unprotected-txs --history.transactions 0

## It is recommend to run fullnode with `--tries-verify-mode none` if you want high performance and care little about state consistency.
./geth --config ./config.toml --datadir ./node  --cache 8000 --rpc.allow-unprotected-txs --history.transactions 0 --tries-verify-mode none

5. Monitor node status

Monitor the log from ./node/chain.log by default. When the node has started syncing, should be able to see the following output:

t=12-13|09:14:56.018 lvl=info msg="Imported new chain segment" number=181544 hash=0x5057c5687ed14e3ed87e1cd11b4d43fecd4ba10b357028be1b33990ebc9a03ba miner=0x4615415aac8609577C4A2aDd55af25FECF5F862f blocks=1 txs=0 blobs=0 mgas=0 elapsed=5.554ms mgasps=0 BAL=false triediffs="382.38 KiB" triedirty="2.12 MiB" trieimutabledirty="0.00 B"
t=12-13|09:14:56.773 lvl=info msg="Imported new chain segment" number=181545 hash=0x1efdbbf4f1e6ed0fdbd071c3633d3fe61aec7d73f32b5ddc78f1217398562f09 miner=0x4615415aac8609577C4A2aDd55af25FECF5F862f blocks=1 txs=0 blobs=0 mgas=0 elapsed=5.474ms mgasps=0 BAL=false triediffs="382.43 KiB" triedirty="2.12 MiB" trieimutabledirty="0.00 B"
t=12-13|09:14:57.523 lvl=info msg="Imported new chain segment" number=181546 hash=0xef72e442ba7a6f4402eebe8d765310de9e476d5500a5054497fdf8c803c72055 miner=0x4615415aac8609577C4A2aDd55af25FECF5F862f blocks=1 txs=0 blobs=0 mgas=0 elapsed=5.475ms mgasps=0 BAL=false triediffs="382.46 KiB" triedirty="2.12 MiB" trieimutabledirty="0.00 B"
t=12-13|09:14:58.273 lvl=info msg="Imported new chain segment" number=181547 hash=0xcca218881234ca42394953f5b8131e33a144415b039806daabc2a0ad2e99dac2 miner=0x4615415aac8609577C4A2aDd55af25FECF5F862f blocks=1 txs=0 blobs=0 mgas=0 elapsed=5.581ms mgasps=0 BAL=false triediffs="382.46 KiB" triedirty="2.12 MiB" trieimutabledirty="0.00 B"

6. Interact with fullnode

Start up geth's built-in interactive JavaScript console, (via the trailing console subcommand) through which you can interact using web3 methods (note: the web3 version bundled within geth is very old, and not up to date with official docs), as well as geth's own management APIs. This tool is optional and if you leave it out you can always attach to an already running geth instance with geth attach.

7. More

More details about running a node and becoming a validator

Note: Although some internal protective measures prevent transactions from crossing over between the main network and test network, you should always use separate accounts for play and real money. Unless you manually move accounts, geth will by default correctly separate the two networks and will not make any accounts available between them.

Configuration

As an alternative to passing the numerous flags to the geth binary, you can also pass a configuration file via:

$ geth --config /path/to/your_config.toml

To get an idea of how the file should look like you can use the dumpconfig subcommand to export your existing configuration:

$ geth --your-favourite-flags dumpconfig

Programmatically interfacing geth nodes

As a developer, sooner rather than later you'll want to start interacting with geth and the H2 network via your own programs and not manually through the console. To aid this, geth has built-in support for a JSON-RPC based APIs (standard APIs, geth specific APIs, and H2's JSON-RPC API Reference). These can be exposed via HTTP, WebSockets and IPC (UNIX sockets on UNIX based platforms, and named pipes on Windows).

The IPC interface is enabled by default and exposes all the APIs supported by geth, whereas the HTTP and WS interfaces need to manually be enabled and only expose a subset of APIs due to security reasons. These can be turned on/off and configured as you'd expect.

HTTP based JSON-RPC API options:

• --http Enable the HTTP-RPC server
• --http.addr HTTP-RPC server listening interface (default: localhost)
• --http.port HTTP-RPC server listening port (default: 8545)
• --http.api API's offered over the HTTP-RPC interface (default: eth,net,web3)
• --http.corsdomain Comma separated list of domains from which to accept cross-origin requests (browser enforced)
• --ws Enable the WS-RPC server
• --ws.addr WS-RPC server listening interface (default: localhost)
• --ws.port WS-RPC server listening port (default: 8546)
• --ws.api API's offered over the WS-RPC interface (default: eth,net,web3)
• --ws.origins Origins from which to accept WebSocket requests
• --ipcdisable Disable the IPC-RPC server
• --ipcpath Filename for IPC socket/pipe within the datadir (explicit paths escape it)

You'll need to use your own programming environments' capabilities (libraries, tools, etc) to connect via HTTP, WS or IPC to a geth node configured with the above flags and you'll need to speak JSON-RPC on all transports. You can reuse the same connection for multiple requests!

Note: Please understand the security implications of opening up an HTTP/WS based transport before doing so! Hackers on the internet are actively trying to subvert H2 nodes with exposed APIs! Further, all browser tabs can access locally running web servers, so malicious web pages could try to subvert locally available APIs!

Running a bootnode

Bootnodes are super-lightweight nodes that are not behind a NAT and are running just discovery protocol. When you start up a node it should log your enode, which is a public identifier that others can use to connect to your node.

First the bootnode requires a key, which can be created with the following command, which will save a key to boot.key:

bootnode -genkey boot.key

This key can then be used to generate a bootnode as follows:

bootnode -nodekey boot.key -addr :30311 -network h2

The choice of port passed to -addr is arbitrary. The bootnode command returns the following logs to the terminal, confirming that it is running:

enode://95d0031f041ec6a74613b56d79bab6513949762a6ee7a671c81e803a022028211087523996a6cb6c26661f6de46b558d0bbf804460bc87f5a469234acc057097@127.0.0.1:0?discport=30311
Note: you're using cmd/bootnode, a developer tool.
We recommend using a regular node as bootstrap node for production deployments.
INFO [08-21|11:11:30.687] New local node record                    seq=1,692,616,290,684 id=2c9af1742f8f85ce ip=<nil> udp=0 tcp=0
INFO [08-21|12:11:30.753] New local node record                    seq=1,692,616,290,685 id=2c9af1742f8f85ce ip=54.217.128.118 udp=30311 tcp=0
INFO [09-01|02:46:26.234] New local node record                    seq=1,692,616,290,686 id=2c9af1742f8f85ce ip=34.250.32.100  udp=30311 tcp=0

Contribution

Thank you for considering helping out with the source code! We welcome contributions from anyone on the internet, and are grateful for even the smallest of fixes!

If you'd like to contribute to h2, please fork, fix, commit and send a pull request for the maintainers to review and merge into the main code base.

Please make sure your contributions adhere to our coding guidelines:

• Code must adhere to the official Go formatting guidelines (i.e. uses gofmt).
• Code must be documented adhering to the official Go commentary guidelines.
• Pull requests need to be based on and opened against the master branch.
• Commit messages should be prefixed with the package(s) they modify.
  • E.g. "eth, rpc: make trace configs optional"

Please see the Developers' Guide for more details on configuring your environment, managing project dependencies, and testing procedures.

License

The h2 library (i.e. all code outside of the cmd directory) is licensed under the GNU Lesser General Public License v3.0, also included in our repository in the COPYING.LESSER file.

The h2 binaries (i.e. all code inside of the cmd directory) is licensed under the GNU General Public License v3.0, also included in our repository in the COPYING file.