cpchain

README

The Cyber Physical Chain

Towards a trusted future with blockchain.

IoT is having a profound and unprecedented impact on human society. However, without trust, it is no more than a castle built on sand. You share the benefits, but with your privacy and financial safety as the cost.

For us, trust is of utmost concern. The mission of cpchain is to build a vital IoT ecosystem which is secured by the blockchain technology. Everyone can enjoy the convenience of M2M payment, self-driving, wearable monitoring, etc. to the fullest extent without worry.

We are shaping a trusted future with blockchain, from smart home to smart city, from edge to cloud computing, with you and with everyone! Please come and join us.

While the codebase has evovled much since the first commit, we owe a debt of thanks to go-ethereum for the initial codebase.

Table of Contents

• Features
• Installation
• Quick Start
• Documentation
• Tools and Libraries
• Contributing
• Contact
• License

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Features

LBFT Consensus

We propose LBFT (Lightweight Byzantine Fault Tolerance), a two-phase algorithm aiming to achieve a fast consensus among the committee. The two phases are prepare and verification respectively.

In prepare phase, the leader of the committee member constructs a block and broadcasts to all members in the committee. Each committee member that receives the block is about to verify the block enters the verification phase. It signs a verified block, and broadcasts to other members. Once a member collects signatures from two thirds of committee members, it commits the block to the network. This two-phase process provides the robustness of our system when at most one third of committee members delay or act unexpectedly.

We further improve our LBFT algorithm to version 2.0, providing higher robust to achieve a consensus among the committee while retaining the properties of liveness and safety. The core ideas are bipartite committee and impeachment process.

The figure below illustrate the detailed steps of LBFT 2.0:

The bipartite committee refers to two separate committees, namely, the proposers committee and the validators committee. A Proposer is a node elected based on its reputation. It takes the responsibility of proposing a block and broadcasting to validators. All proposers of a certain term constitute the proposers committee.

Meanwhile, the validator committee consists of nodes nominated by CPC Foundation, governments and companies. Unlike proposers, validators cannot propose a block in normal cases. This committee validates a newly proposed block in three phases, similar to PBFT (Practical Byzantine Fault Tolerance). And it can also tolerate at most one third faulty or non-responding members.

This bipartite structure eliminates the role of the primary node of traditional PBFT protocol. In addition, it guarantees the independence of block proposal and validation, which decreases the risk and feasibility of byzantine faults.

To handle abnormal cases, we propose impeachment, a novel two-phase protocol assuring the properties of both liveness and safety in LBFT 2.0. When a validator suspects the proposer is faulty, it proposes an impeach block on behalf of the faulty proposer. The validators committee is about to achieve a consensus on this impeach block if a quorum of validators considers the proposer faulty.

Private Transactions

This feature can be enabled during compilation. Currently disabled on mainnet.

We design a data privacy mechanism that allows users to conduct private transactions on cpchain in a secure manner. Other than the valid participants, no one else has the ability to see the transaction. While private transactions are invisible for outsiders, we keep critical footprint of a transaction on chain for later audition.

A user scenario:

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Installation

Download stable binaries

All versions of cpchain are built and available for download here.

The download page provides a zip file, containing the executable files that can be used without installing.

Building from source

Install latest distribution of Go if it has yet to be installed. Do not forget to configure $GOPATH. Then clone the repository to a directory that you'd like:

git clone https://bitbucket.org/cpchain/chain.git

Finally, build the programs using the following commands.

cd chain
make clear
make all

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Quick Start

After installation, you are able to start running cpchain. Refer to ./build/bin/cpchain --help to check the help menu.

Connect to testnet

cd build/bin
./cpchain run --runmode testnet

Create an account

./cpchain account new --datadir ./datadir

Run a private network

cd examples/cpchain
./cpchain-all.sh

check logs
tail -f data/logs/*.log | grep number=

Run a local node

./cpchain run --datadir ./datadir --unlock <You Address>

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Documentation

The above should be enough to get you up to speed. For details, please visit our documentation portal.

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Tools and Libraries

CPChain Blockchain Explorer

Check our explorer and its website repository. It shows the ongoing transactions and blocks.

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Contributing

Your hacks are always welcome!🔨🔨🔨

Please fork on bitbucket and make pull request there.

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Contact

Shout to us at one of the following places!

• Website at cpchain.io
• Twitter at @cpchain_io
• Telegram at cpchain

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License

Unless otherwise specified in the source files (or the vanilla files from go-ethereum), the licence by default is

Copyright 2018-2025 © The CPChain Foundation

Documentation

Index

• Variables
• type CallMsg
• type ChainReader
• type ChainStateReader
• type ChainSyncReader
• type ContractCaller
• type FilterQuery
• type GasEstimator
• type GasPricer
• type LogFilterer
• type PendingContractCaller
• type PendingStateEventer
• type PendingStateReader
• type Subscription
• type SyncProgress
• type TransactionReader
• type TransactionSender

Variables

var NotFound = errors.New("not found")

NotFound is returned by API methods if the requested item does not exist.

Types

type CallMsg

type CallMsg struct {
	From     common.Address  // the sender of the 'transaction'
	To       *common.Address // the destination contract (nil for contract creation)
	Gas      uint64          // if 0, the call executes with near-infinite gas
	GasPrice *big.Int        // wei <-> gas exchange ratio
	Value    *big.Int        // amount of wei sent along with the call
	Data     []byte          // input data, usually an ABI-encoded contract method invocation
}

CallMsg contains parameters for contract calls.

type ChainReader

type ChainReader interface {
	BlockByHash(ctx context.Context, hash common.Hash) (*types.Block, error)
	BlockByNumber(ctx context.Context, number *big.Int) (*types.Block, error)
	HeaderByHash(ctx context.Context, hash common.Hash) (*types.Header, error)
	HeaderByNumber(ctx context.Context, number *big.Int) (*types.Header, error)
	TransactionCount(ctx context.Context, blockHash common.Hash) (uint, error)
	TransactionInBlock(ctx context.Context, blockHash common.Hash, index uint) (*types.Transaction, error)

	// This method subscribes to notifications about changes of the head block of
	// the canonical chain.
	SubscribeNewHead(ctx context.Context, ch chan<- *types.Header) (Subscription, error)
}

ChainReader provides access to the blockchain. The methods in this interface access raw data from either the canonical chain (when requesting by block number) or any blockchain fork that was previously downloaded and processed by the node. The block number argument can be nil to select the latest canonical block. Reading block headers should be preferred over full blocks whenever possible.

The returned error is NotFound if the requested item does not exist.

type ChainStateReader

type ChainStateReader interface {
	BalanceAt(ctx context.Context, account common.Address, blockNumber *big.Int) (*big.Int, error)
	StorageAt(ctx context.Context, account common.Address, key common.Hash, blockNumber *big.Int) ([]byte, error)
	CodeAt(ctx context.Context, account common.Address, blockNumber *big.Int) ([]byte, error)
	NonceAt(ctx context.Context, account common.Address, blockNumber *big.Int) (uint64, error)
}

ChainStateReader wraps access to the state trie of the canonical blockchain. Note that implementations of the interface may be unable to return state values for old blocks. In many cases, using CallContract can be preferable to reading raw contract storage.

type ChainSyncReader

type ChainSyncReader interface {
	SyncProgress(ctx context.Context) (*SyncProgress, error)
}

ChainSyncReader wraps access to the node's current sync status. If there's no sync currently running, it returns nil.

type ContractCaller

type ContractCaller interface {
	CallContract(ctx context.Context, call CallMsg, blockNumber *big.Int) ([]byte, error)
}

A ContractCaller provides contract calls, essentially transactions that are executed by the EVM but not mined into the blockchain. ContractCall is a low-level method to execute such calls. For applications which are structured around specific contracts, the abigen tool provides a nicer, properly typed way to perform calls.

type FilterQuery

type FilterQuery struct {
	FromBlock *big.Int         // beginning of the queried range, nil means genesis block
	ToBlock   *big.Int         // end of the range, nil means latest block
	Addresses []common.Address // restricts matches to events created by specific contracts

	// The Topic list restricts matches to particular event topics. Each event has a list
	// of topics. Topics matches a prefix of that list. An empty element slice matches any
	// topic. Non-empty elements represent an alternative that matches any of the
	// contained topics.
	//
	// Examples:
	// {} or nil          matches any topic list
	// {{A}}              matches topic A in first position
	// {{}, {B}}          matches any topic in first position, B in second position
	// {{A}, {B}}         matches topic A in first position, B in second position
	// {{A, B}}, {C, D}}  matches topic (A OR B) in first position, (C OR D) in second position
	Topics [][]common.Hash
}

FilterQuery contains options for contract log filtering.

type GasEstimator

type GasEstimator interface {
	EstimateGas(ctx context.Context, call CallMsg) (uint64, error)
}

GasEstimator wraps EstimateGas, which tries to estimate the gas needed to execute a specific transaction based on the pending state. There is no guarantee that this is the true gas limit requirement as other transactions may be added or removed by miners, but it should provide a basis for setting a reasonable default.

type GasPricer

type GasPricer interface {
	SuggestGasPrice(ctx context.Context) (*big.Int, error)
}

GasPricer wraps the gas price oracle, which monitors the blockchain to determine the optimal gas price given current fee market conditions.

type LogFilterer

type LogFilterer interface {
	FilterLogs(ctx context.Context, q FilterQuery) ([]types.Log, error)
	SubscribeFilterLogs(ctx context.Context, q FilterQuery, ch chan<- types.Log) (Subscription, error)
}

LogFilterer provides access to contract log events using a one-off query or continuous event subscription.

Logs received through a streaming query subscription may have Removed set to true, indicating that the log was reverted due to a chain reorganisation.

type PendingContractCaller

type PendingContractCaller interface {
	PendingCallContract(ctx context.Context, call CallMsg) ([]byte, error)
}

PendingContractCaller can be used to perform calls against the pending state.

type PendingStateEventer

type PendingStateEventer interface {
	SubscribePendingTransactions(ctx context.Context, ch chan<- *types.Transaction) (Subscription, error)
}

A PendingStateEventer provides access to real time notifications about changes to the pending state.

type PendingStateReader

type PendingStateReader interface {
	PendingBalanceAt(ctx context.Context, account common.Address) (*big.Int, error)
	PendingStorageAt(ctx context.Context, account common.Address, key common.Hash) ([]byte, error)
	PendingCodeAt(ctx context.Context, account common.Address) ([]byte, error)
	PendingNonceAt(ctx context.Context, account common.Address) (uint64, error)
	PendingTransactionCount(ctx context.Context) (uint, error)
}

A PendingStateReader provides access to the pending state, which is the result of all known executable transactions which have not yet been included in the blockchain. It is commonly used to display the result of ’unconfirmed’ actions (e.g. wallet value transfers) initiated by the user. The PendingNonceAt operation is a good way to retrieve the next available transaction nonce for a specific account.

type Subscription

type Subscription interface {
	// Unsubscribe cancels the sending of events to the data channel
	// and closes the error channel.
	Unsubscribe()
	// Err returns the subscription error channel. The error channel receives
	// a value if there is an issue with the subscription (e.g. the network connection
	// delivering the events has been closed). Only one value will ever be sent.
	// The error channel is closed by Unsubscribe.
	Err() <-chan error
}

Subscription represents an event subscription where events are delivered on a data channel.

type SyncProgress

type SyncProgress struct {
	StartingBlock uint64 // Block number where sync began
	CurrentBlock  uint64 // Current block number where sync is at
	HighestBlock  uint64 // Highest alleged block number in the chain
	PulledStates  uint64 // Number of state trie entries already downloaded
	KnownStates   uint64 // Total number of state trie entries known about
}

SyncProgress gives progress indications when the node is synchronising with the network.

type TransactionReader

type TransactionReader interface {
	// TransactionByHash checks the pool of pending transactions in addition to the
	// blockchain. The isPending return value indicates whether the transaction has been
	// mined yet. Note that the transaction may not be part of the canonical chain even if
	// it's not pending.
	TransactionByHash(ctx context.Context, txHash common.Hash) (tx *types.Transaction, isPending bool, err error)
	// TransactionReceipt returns the receipt of a mined transaction. Note that the
	// transaction may not be included in the current canonical chain even if a receipt
	// exists.
	TransactionReceipt(ctx context.Context, txHash common.Hash) (*types.Receipt, error)
}

TransactionReader provides access to past transactions and their receipts. Implementations may impose arbitrary restrictions on the transactions and receipts that can be retrieved. Historic transactions may not be available.

Avoid relying on this interface if possible. Contract logs (through the LogFilterer interface) are more reliable and usually safer in the presence of chain reorganisations.

The returned error is NotFound if the requested item does not exist.

type TransactionSender

type TransactionSender interface {
	SendTransaction(ctx context.Context, tx *types.Transaction) error
}

TransactionSender wraps transaction sending. The SendTransaction method injects a signed transaction into the pending transaction pool for execution. If the transaction was a contract creation, the TransactionReceipt method can be used to retrieve the contract address after the transaction has been mined.

The transaction must be signed and have a valid nonce to be included. Consumers of the API can use package accounts to maintain local private keys and need can retrieve the next available nonce using PendingNonceAt.