CKB SDK Golang

Golang SDK for Nervos CKB.

The ckb-sdk-go is still under development and considered to be a work in progress. You should get familiar with CKB transaction structure and RPC before using it.

Installation

Minimum requirements

Components	Version	Description
Golang	≥ 1.11.5	Go programming language

Install

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

Quick start

Setup

ckb-sdk-go provides a convenient client to help you easily interact with CKB, CKB-indexer or Mercury node.

ckbClient, err := rpc.Dial("http://127.0.0.1:8114")
//!!NOTE: 
// Indexer RPCs are now integrated into CKB, people now should directly use CKB clients, not the legacy indexer client
// check https://github.com/nervosnetwork/ckb/blob/develop/rpc/README.md#module-indexer for equivalent RPCs
//indexerClient, err := indexer.Dial("http://127.0.0.1:8114")
mercuryClient , err := mercury.Dial("http://127.0.0.1:8116")

You can call JSON-RPC APIs via these clients.

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

For examples, you can check collector usage examples

For more details about JSON-RPC APIs, please check:

• CKB RPC doc
• CKB Indexer Module RPC doc
• Mercury RPC doc.

Build transaction manually

Ckb-sdk-go provides a signer mechanism to sign transaction. The only thing you need to provide is an instance of TransactionWithScriptGroups and transaction signer will do all signing jobs for you. Here is the code to construct a TransactionWithScriptGroups by manual.

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,
}

Refer here to see how to sign and send transaction once you have the instance of TransactionWithScriptGroups.

Build transaction with Mercury

Mercury is an application for better interaction with CKB chain, providing many useful JSON-RPC APIs for development like querying transactions or getting UDT asset information. You need to deploy your own mercury server and sync data with the latest network before using it.

Mercury is another way to build transaction. With the help of Mercury, you can build a transaction by simply calling a JSON-RPC API. Here we show how to build a CKB transfer transaction with mercury.

sender := "ckt1qzda0cr08m85hc8jlnfp3zer7xulejywt49kt2rr0vthywaa50xwsq0yvcdtsu5wcr2jldtl72fhkruf0w5vymsp6rk9r"
receiver := "ckt1qzda0cr08m85hc8jlnfp3zer7xulejywt49kt2rr0vthywaa50xwsqvglkprurm00l7hrs3rfqmmzyy3ll7djdsujdm6z"
ckbAmount := amount.CkbToShannon(100)  // Convert CKB to Shannon (1 CKB = 10^8 Shannon)
req := &model.SimpleTransferPayload{
	AssetInfo: model.NewCkbAsset(),
	From:       []string{sender},
	To:          []*model.ToInfo{{receiver, ckbAmount}},
	FeeRate:   1000,
}
// Get an unsigned raw transaction with the help of Mercury
txWithScriptGroups, err := mercuryClient.BuildSimpleTransferTransaction(req)

For more use cases of Mercury, please refer to Mercury test cases and Mercury JSON-RPC documentation.

Sign and 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.

// You can get txWithScriptGroups by manual or by mercury
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)

Please note that before signing and sending transaction, you need to prepare a raw transaction represented by an instance of struct TransactionWithScriptGroups. You can get it by Mercury or by ckb-indexer.

Generate a new address

In CKB world, a lock script can be represented as an address. secp256k1_blake160_signhash_all is the most common used address and here we show 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()

For more details please about CKB address refer to CKB rfc 0021.

Convert public key to address

Convert elliptic curve public key to an address (secp256k1_blake160_signash_all)

// 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

Short address and full bech32 address are deprecated. The standard address encoded way is bech32m. You can still parse address from an encoded string address and then get its network, script and encoded string of other format.

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

License

The SDK is available as open source under the terms of the MIT License.