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Expose hardened bit in Bip32ECKeyPair for other libraries #838

macalinao opened this Issue Jan 8, 2019 · 2 comments


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macalinao commented Jan 8, 2019

Is there a reason why the hardened bit is package-private? It's needed to actually derive HD wallet keys.


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macalinao commented Jan 8, 2019

For future readers that are trying to use web3j to generate bip44 hdwallets, here's my scala code to do so:

import abacus.server.util.StringUtils
import org.web3j.crypto._

object Wallets {

  val HardenedBit = 0x80000000
  // no idea why this is private.

  val random = new SecureRandom()

  def generateMnemonicAndPassphrase(): (String, String) = {
    val initialEntropy = new Array[Byte](16)
    val mnemonic = MnemonicUtils.generateMnemonic(initialEntropy)
    val passphrase = StringUtils.secureAlphanumeric(32)
    (mnemonic, passphrase)

  def generateMasterKey(
    mnemonic: String,
    passphrase: String,
  ): Bip32ECKeyPair = {
    val seed = MnemonicUtils.generateSeed(mnemonic, passphrase)

  def generateKeyCredentials(
    mnemonic: String,
    passphrase: String,
    index: Int,
  ): Credentials = {
    // ledger does things this way according to
    val path =
      Array[Int](44 | HardenedBit, 60 | HardenedBit, index | HardenedBit, 0, 0)
        generateMasterKey(mnemonic, passphrase),


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MDhondt commented Jan 18, 2019

I too vote to make this HARDENED_BIT a public field.

In Java:

public ECKeyPair generateKeyPair(String mnemonic, String passphrase, String derivationPath) {
    int HARDENED_BIT = 0x80000000; // This should be statically importable from org.web3j.crypto.Bip32ECKeyPair

    Integer purpose, coinType, account, change, addressIndex; // parse derivationPath

    Bip32ECKeyPair masterKeypair = Bip32ECKeyPair.generateKeyPair(MnemonicUtils.generateSeed(mnemonic, passphrase));
    int[] path = {purpose | HARDENED_BIT, coinType | HARDENED_BIT, account | HARDENED_BIT, change, addressIndex};
    return Bip32ECKeyPair.deriveKeyPair(masterKeypair, path);

MDhondt added a commit to MDhondt/web3j that referenced this issue Jan 18, 2019

@snazha-blkio snazha-blkio added this to the 4.1.x milestone Jan 20, 2019

@snazha-blkio snazha-blkio self-assigned this Jan 20, 2019

@snazha-blkio snazha-blkio modified the milestones: 4.1.2, 4.1.x Mar 6, 2019

snazha-blkio added a commit that referenced this issue Mar 6, 2019

@snazha-blkio snazha-blkio modified the milestones: 4.1.x, 4.1.2 Mar 6, 2019

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