Go

Introduction

The CKB-SDK-Go is a robust and scalable toolkit designed for developers building on the Nervos CKB blockchain with the Go programming language. Go's simplicity and powerful concurrency features make it ideal for developing scalable blockchain services and applications. This SDK is well-suited for server-side applications, networked services, and other use cases requiring high performance and reliability.

Requirements

Components	Version	Description
Golang	≥ 1.11.5	Go programming language

To verify that you have Golang installed, you can run this in your terminal:

go version

Setup Project

1. Create a new project: Open a terminal and run the following commands to create a folder for your Go project:

mkdir ckb-go-example
cd ckb-go-example
go mod init ckb-go-example

2. Install ckb-sdk-go: Add the ckb-sdk-go dependency to your project:

go get -v github.com/nervosnetwork/ckb-sdk-go/v2

3. Build the project: Run the following command in the project root directory:

go build

Setup Client

CKB-SDK-Go provides a convenient client that enables you to easily interact with CKB nodes. You can connect to different networks (Testnet, Devnet, and Mainnet) by specifying the appropriate URL.

import (
	"github.com/nervosnetwork/ckb-sdk-go/v2/rpc"
)

testnetURL := "https://testnet.ckb.dev" // Testnet
devnetURL := "http://127.0.0.1:8114" // Devnet
mainnetURL := "https://mainnet.ckb.dev/rpc" // Mainnet

// Connect to Testnet
ckbClient, err := rpc.Dial(testnetURL)

Examples

Get Block Info

You can call JSON-RPC APIs via the above client. For example, you can get a block info by:

block, err := ckbClient.GetBlock(context.Background(), types.HexToHash("0x77fdd22f6ae8a717de9ae2b128834e9b2a1424378b5fc95606ba017aab5fed75"))

For more details about JSON-RPC APIs, please refer to CKB RPC

Build a Transaction

Here's an example to construct a TransactionWithScriptGroups.

tx := &types.Transaction{
	Version: 0,
	CellDeps: []*types.CellDep{
		&types.CellDep{
			OutPoint: &types.OutPoint{
				TxHash: types.HexToHash("0xf8de3bb47d055cdf460d93a2a6e1b05f7432f9777c8c474abf4eec1d4aee5d37"),
				Index:  0,
			},
			DepType: types.DepTypeDepGroup,
		},
	},
	HeaderDeps: nil,
	Inputs: []*types.CellInput{
		&types.CellInput{
			Since: 0,
			PreviousOutput: &types.OutPoint{
				TxHash: types.HexToHash("0x2ff7f46d509c85e1878cf091aef0ba0b89f34f9fea9e8bc868aed2d627490512"),
				Index:  1,
			},
		},
	},
	Outputs: []*types.CellOutput{
		&types.CellOutput{
			Capacity: 10000000000,
			Lock: &types.Script{
				CodeHash: types.HexToHash("0x9bd7e06f3ecf4be0f2fcd2188b23f1b9fcc88e5d4b65a8637b17723bbda3cce8"),
				HashType: types.HashTypeType,
				Args:     common.FromHex("0x3f1573b44218d4c12a91919a58a863be415a2bc3"),
			},
			Type: nil,
		},
		&types.CellOutput{
			Capacity: 90000000000,
			Lock: &types.Script{
				CodeHash: types.HexToHash("0x9bd7e06f3ecf4be0f2fcd2188b23f1b9fcc88e5d4b65a8637b17723bbda3cce8"),
				HashType: types.HashTypeType,
				Args:     common.FromHex("0xb1d41a1fb06f782cf10a87f3e49e80711af63fcf"),
			},
			Type: nil,
		},
	},
	OutputsData: make([][]byte, 2),
	Witnesses: [][]byte{
		common.FromHex("0x55000000100000005500000055000000410000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"),
	},
}

scriptGroups := []*transaction.ScriptGroup{
	&transaction.ScriptGroup{
		Script: types.Script{
			CodeHash: types.HexToHash("0x9bd7e06f3ecf4be0f2fcd2188b23f1b9fcc88e5d4b65a8637b17723bbda3cce8"),
			HashType: types.HashTypeType,
			Args:     common.FromHex("0x3f1573b44218d4c12a91919a58a863be415a2bc3"),
		},
		GroupType:    types.ScriptTypeLock,
		InputIndices: []uint32{0},
	},
}
txWithScriptGroups := &transaction.TransactionWithScriptGroups{
	TxView:       tx,
	ScriptGroups: scriptGroups,
}

Sign & Send Transaction

Once the TransactionWithScriptGroups is prepared, you can follow these steps to sign and send transaction to CKB network:

1. Sign transaction with your private key.
2. Send Signed transaction to CKB node, and wait for it to be confirmed.

note

The address and key are for demo purposes only and should not be used in a production environment.

// Your built txWithScriptGroups
var txWithScriptGroups *transaction.TransactionWithScriptGroups
// 0. Set your private key
privKey := "0xccb083b37aa346c5ce2e1f99a687a153baa04052f26db6ab3c26d6a4cc15c5f1"
// 1. Sign transaction with your private key
txSigner := signer.GetTransactionSignerInstance(types.NetworkTest)
txSigner.SignTransactionByPrivateKeys(txWithScriptGroups, privKey)
// 2. Send transaction to CKB node
txHash, err := ckbClient.SendTransaction(context.Background(), txWithScriptGroups.TxView)

Generate a New Address

In CKB world, a Lock Script

A Script that enforces access and ownership of a Cell.

can be represented as an address. secp256k1_blake160_signhash_all is the most commonly used address. Here's how to generate it.

// Generate a new address randomly
key, err := secp256k1.RandomNew()
if err != nil {
	// handle error
}
script := systemscript.Secp256K1Blake160SignhashAll(key)
addr := &address.Address{Script: script, Network: types.NetworkTest}
encodedAddr, err := addr.Encode()

Convert Public Key to Address

Convert elliptic curve public key to an address (secp256k1_blake160):

// You should provide an elliptic curve public key of compressed format, with 33 bytes.
script, err := systemscript.Secp256K1Blake160SignhashAllByPublicKey("0x03a0a7a7597b019828a1dda6ed52ab25181073ec3a9825d28b9abbb932fe1ec83d")
if err != nil {
	// handle error
}
addr := &address.Address{Script: script, Network: types.NetworkTest}

Parse Address

Parse an address from an encoded string and get its network, Script, and encoded string in other formats.

addr, err := address.Decode("ckt1qyqxgp7za7dajm5wzjkye52asc8fxvvqy9eqlhp82g")
if err != nil {
	// handle error
}
script := addr.Script
network := addr.Network

note

Short address and full bech32 address are deprecated. For more details about addresses, check out CKB Address and RFC-0021.

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Additional Resources

• Github
• Examples to show how to use this sdk to interact with CKB's RPC, transaction, and Nervos DAO (deposit and withdraw).
• Changelog