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Dart package to assist smooth development on VeChain for developers and hobbyists.

VeChain Thor Devkit (SDK) in Dart #

To use the library in your Flutter application refer to the official documentation on

You can skip this step if you want to contribute to the development of this library.

Dart package to assist smooth development on VeChain for developers and hobbyists.

Public key, private key, address conversion.
Mnemonic Wallets.
HD Wallet.
Various Hashing functions.
Signing messages.
Verify signature of messages.
Bloom filter.
Transaction Assembling (Multi-task Transaction, MTT).
Fee Delegation Transaction (VIP-191).
Self-signed Certificate (VIP-192).
ABI decoding of "functions" and "events" in logs.

... and will always be updated with the newest features on VeChain.

Steps to contribute to the library development and test the package: #

If you want to contribute to the library development, you probably want to clone this repository on your local machine. Once you have the source code locally on your machine, you can look at the code with the IDE of your choice.

If you want to suggest changes or updates please create a pull request that can be reviewed by the maintainers and the community.

If you want to run the tests you can follow this steps (linux or macOS):

  • install git if you have not installed it yet
  • install dart if you have not installed it yet
  • chose a folder on your machine to host this project e.g. ~/Documents/
  • open the terminal and get into the folder you just chose, e.g. cd ~/Documents/
  • clone this repository on your local machine in the folder you have just created using git clone
  • go further down in the directory hiererchy until your terminal points to ~/Documents/thor-devkit.dart/thor_devkit_dart (you can verify at what level you are using the pwd command. E.g. cd ~/Documents/thor-devkit.dart/thor_devkit_dart
  • run dart test

This shall run the tests that have been written to verify the correct functioning of the thor_devkit functionality.

Usage #

Private/Public Keys #

import 'package:thor_devkit_dart/crypto/address.dart';
import 'package:thor_devkit_dart/crypto/secp256k1.dart';
import 'package:thor_devkit_dart/utils.dart';

//generate a new private key
BigInt priv = generatePrivateKey();
//derive public key from given private key
Uint8List pub = derivePublicKey(priv, false); // byte[65].
//derive address from given public key
Uint8List addr = Address.publicKeyToAddressBytes(pub);
//turn address into a hex string and prepend 0x to get a valid address String
String address = "0x" + bytesToHex(addr);
// address should look like this: 0x63ad8a6d015ae579ad128e0c63040bb860cc5d34

String checksumAddress = Address.toChecksumAddress(address);
// checksumAddress should look like this: 0x63ad8A6D015aE579ad128e0c63040bB860Cc5D34

Sign & Verify Signatures #

import 'package:thor_devkit_dart/crypto/keccak.dart';
import 'package:thor_devkit_dart/crypto/secp256k1.dart';
import 'package:thor_devkit_dart/crypto/thor_signature.dart';
import 'package:thor_devkit_dart/utils.dart';
Uint8List priv = hexToBytes(
); // byte[32].

Uint8List msgHash = keccak256(
    [asciiToBytes("hello world")]
); // byte[32].

// Sign the message hash.
ThorSignature sig = sign(msgHash, priv);

//you can turn a ThorSignature object into bytes
Uint8List sigBytes = sig.serialize();

// Recover public key from given message hash and signature.
Uint8List pub = recover( msgHash, sig); // byte[65].

// Verify if the public key matches.
expect(pub, derivePublicKey(bytesToInt(priv), false));// true.

Mnemonic Wallet #

import 'package:thor_devkit_dart/crypto/mnemonic.dart';

    List<String> words = Mnemonic.generate(entropyLength: 128);
// [carry, slow, attack, december, number, film, scale, faith, can, old, cage, expose]

    bool flag = Mnemonic.validate(words);
    print(flag); // true.

// Quickly get a Bip32 master seed for HD wallets.
// How to use the seed? See "HD wallet" below.
    Uint8List seed = Mnemonic.deriveSeed(words);

// Quickly get a private key at index 0.
// Need to generate more? See "HD wallet" below.
    Uint8List priv = Mnemonic.derivePrivateKey(words);

HD Wallet #

Hierarchical Deterministic Wallets. See bip-32 and bip-44.

import 'package:thor_devkit_dart/crypto/address.dart';
import 'package:thor_devkit_dart/crypto/hd_node.dart';
import 'package:thor_devkit_dart/utils.dart';

    List<String> words = [

// Construct an HD node from words. (Recommended)
    HDNode topMostNode = HDNode.fromMnemonic(words);

// Or, construct from seed. (Advanced)
    String seed_hex =

    HDNode topMostNode2 = HDNode.fromSeed(hexToBytes(seed_hex));

// Access the HD node's properties.
    Uint8List priv = topMostNode.privateKey!; //private key can be null
    Uint8List pub = topMostNode.publicKey;
    Uint8List cc = topMostNode.chainCode;

// Or, construct from a private key. (Advanced)
    HDNode topMostNode3 = HDNode.fromPrivateKey(priv, cc);

// Or, construct from a public key. (Advanced)
// Notice: This HD node CANNOT derive child HD node contains "private key".
    HDNode topMostNode4 = HDNode.fromPublicKey(pub, cc);

// Let it derive further child HD nodes.
    for (int i = 0; i < 3; i++) {
      HDNode child = topMostNode.derive(i);
      print("addr: " + Address.publicKeyToAddressString(child.publicKey));
      print("priv: " + bytesToHex(child.privateKey!));
// addr: 0x339fb3c438606519e2c75bbf531fb43a0f449a70
// priv: 27196338e7d0b5e7bf1be1c0327c53a244a18ef0b102976980e341500f492425
// addr: 0x5677099d06bc72f9da1113afa5e022feec424c8e
// priv: cf44074ec3bf912d2a46b7c84fa6eb745652c9c74e674c3760dc7af07fc98b62
// addr: 0x86231b5cdcbfe751b9ddcd4bd981fc0a48afe921
// priv: 2ca054a50b53299ea3949f5362ee1d1cfe6252fbe30bea3651774790983e9348

Keystore #

import 'package:thor_devkit_dart/crypto/keystore.dart';

    String ks = """
    "version": 3,
    "id": "f437ebb1-5b0d-4780-ae9e-8640178ffd77",
    "address": "dc6fa3ec1f3fde763f4d59230ed303f854968d26",
        "kdf": "scrypt",
        "kdfparams": {
            "dklen": 32,
            "salt": "b57682e5468934be81217ad5b14ca74dab2b42c2476864592c9f3b370c09460a",
            "n": 262144,
            "r": 8,
            "p": 1
        "cipher": "aes-128-ctr",
        "ciphertext": "88cb876f9c0355a89cad88ee7a17a2179700bc4306eaf78fa67320efbb4c7e31",
        "cipherparams": {
            "iv": "de5c0c09c882b3f679876b22b6c5af21"
        "mac": "8426e8a1e151b28f694849cb31f64cbc9ae3e278d02716cf5b61d7ddd3f6e728"

// Must be UTF_8 string.
    String password = "123456";
// Decrypt from keystore to a private key.
    Uint8List priv = Keystore.decrypt(ks, password);
// Encrypt from a private key to a keystore.
    String ks2 = Keystore.encrypt(priv, password);

Hash #

import 'package:thor_devkit_dart/utils.dart';
import 'package:thor_devkit_dart/crypto/keccak.dart';

    String input = "hello world";
    List<String> inputs = ["hello", " ", "world"];

    Uint8List output1 = keccak256([asciiToBytes(input)]);
    Uint8List output2 = keccak256([
    ]); // output1 == outpu2

    Uint8List output3 = blake2b256([asciiToBytes(input)]);
    Uint8List output4 = blake2b256([
    ]); // output3 == outpu4

Bloom Filter #

import 'package:thor_devkit_dart/function.dart';
import 'package:thor_devkit_dart/utils.dart';
import 'package:thor_devkit_dart/bloom.dart';

// Create a bloom filter that stores 100 items.
    int k = Bloom.estimateK(100);
    Bloom b = Bloom(k);

// Add to it.
    b.add(Uint8List.fromList(utf8.encode("hello world")));

// Test if exists.
    bool contain =
        b.mightContain(Uint8List.fromList(utf8.encode("hello world"))); // true.
    bool contain2 = b.mightContain(
        Uint8List.fromList(utf8.encode("bye bye blue bird"))); // false.

ABI: Enode Function Calls. #

    String f1 = """
    "constant": false,
    "inputs": [
            "name": "a1",
            "type": "uint256"
            "name": "a2",
            "type": "string"
    "name": "f1",
    "outputs": [
            "name": "r1",
            "type": "address"
            "name": "r2",
            "type": "bytes"
    "payable": false,
    "stateMutability": "nonpayable",
    "type": "function"
"""; // Function definition.

    ThorFunction f = ThorFunction(f1);

// Calculate the selector of the function.
    expect(bytesToHex(f.selector()), "27fcbb2f");

// Encode a function call with params (1, "foo").
        f.encode([BigInt.from(1), "foo"]),

ABI: Decode Function Return #

String f1 = """
    "constant": false,
    "inputs": [
            "name": "a1",
            "type": "uint256"
            "name": "a2",
            "type": "string"
    "name": "f1",
    "outputs": [
            "name": "r1",
            "type": "address"
            "name": "r2",
            "type": "bytes"
    "payable": false,
    "stateMutability": "nonpayable",
    "type": "function"
"""; // Function definition.

ThorFunction f = ThorFunction(f1);

// The function call return value.
String data = "000000000000000000000000abc000000000000000000000000000000000000100000000000000000000000000000000000000000000000000000000000000400000000000000000000000000000000000000000000000000000000000000003666f6f0000000000000000000000000000000000000000000000000000000000";

// f.decodeReturnV1() returns  V1ParamWrapper objects
List<V1ParamWrapper> result = f.decodeReturnV1(data);
result[0].name;  // "r1"
result[0].canonicalType; //"address"
result[0].value; // "0xabc0000000000000000000000000000000000001"
result[1].name;  // "r2"
result[1].canonicalType; // "bytes"
result[1].value; // "0x666f6f"

Transaction #

// Transaction Structure:
// See:
import 'package:thor_devkit_dart/crypto/blake2b.dart';
import 'package:thor_devkit_dart/crypto/secp256k1.dart';
import 'package:thor_devkit_dart/crypto/thor_signature.dart';
import 'package:thor_devkit_dart/transaction.dart';
import 'package:thor_devkit_dart/types/clause.dart';
import 'package:thor_devkit_dart/utils.dart';

// Set up clauses.
    List<Clause> clauses = [
          "0x7567d83b7b8d80addcb281a71d54fc7b3364ffed", // to
          "10000", // value
          "0x000000606060" // data
      Clause("0x7567d83b7b8d80addcb281a71d54fc7b3364ffed", "20000",

// Create a tx.
    Transaction tx = Transaction(
        39, // chainTag
        "0x00000000aabbccdd", // blockRef
        "32", // expiration
        clauses, // clauses
        "128", // gasPriceCoef
        "21000", // gas
        null, // dependsOn
        "12345678", // nonce
        null // reserved

// Sign the tx.
    Uint8List privateKey = hexToBytes(
    Uint8List h = blake2b256([tx.encode()] // unsigned tx encoded.
    ThorSignature sig = sign(h, privateKey);

// Set signature on tx.
    tx.signature = sig.serialize();

// Properties.
    tx.getIntrinsicGas(); // 37432

// Signed tx encoded.
    Uint8List encodedTx = tx.encode();
// Then you can HTTP POST to send the encodedTx to VeChain...
// See the REST API details:
// testnet:
// mainnet:

Sign & Verify Certificate (VIP-192) #

import 'package:thor_devkit_dart/crypto/blake2b.dart';
import 'package:thor_devkit_dart/crypto/secp256k1.dart';
import 'package:thor_devkit_dart/utils.dart';
import 'package:thor_devkit_dart/certificate.dart';
import 'package:thor_devkit_dart/crypto/address.dart';

/* For a Certificate looks like this:
  "purpose": "identification",
  "payload": {
    "type": "text",
    "content": "fyi"
  "domain": "localhost",
  "timestamp": 1545035330,
  "signer": "0xd989829d88b0ed1b06edf5c50174ecfa64f14a64"

Uint8List priv = hexToBytes("7582be841ca040aa940fff6c05773129e135623e41acce3e0b8ba520dc1ae26a");
Uint8List addr = Address.publicKeyToAddressBytes(derivePublicKey(bytesToInt(priv), false));

// Create a Certificate.
Map<String, String> payload = {
    "type": "text",
    "content": "fyi"

Certificate c = Certificate(
    "identification",               // purpose
    payload,                        // payload
    "localhost",                    // domian
    1545035330,                     // timestamp
    "0x" + bytesToHex(addr),        // signer
    signature: null                 //optional parameter signature, default null

// Or create from some external json string.
// Certificate c2 = Certificate.fromJsonString(...);

// Or create from some external Map<String, Object>.
// Certificate c3 = Certificate.fromMap(...);

// Sign the cert.
// 1) Calculate signature.
String j = c.toJsonString();
Uint8List signingHash = blake2b256([Uint8List.fromList(utf8.encode(j))]);
Uint8List sig = sign(signingHash, priv).serialize();
// 2) Set signature on cert.
c.signature = "0x" + bytesToHex(sig);
// 3) Verify. If signature matches this cert.

Knowledge #

Name Bytes Description
private key 32 random number
public key 65 uncompressed, starts with "04"
address 20 derived from public key
keccak256 32 hash
blake2b256 32 hash
message hash 32 hash of a message
signature 65 signing result, last bit as recovery parameter
seed 64 used to derive bip32 master key
pub points


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Dart package to assist smooth development on VeChain for developers and hobbyists.

Repository (GitHub)
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API reference


Icon for licenses.LGPL-3.0 (LICENSE)


base_x, bip32, bip39, convert, pointycastle, rlp, web3dart


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