Ejemplo n.º 1
0
  /** Convert mnemonic word list to original entropy value. */
  public byte[] toEntropy(List<String> words)
      throws MnemonicException.MnemonicLengthException, MnemonicException.MnemonicWordException,
          MnemonicException.MnemonicChecksumException {
    if (words.size() % 3 > 0)
      throw new MnemonicException.MnemonicLengthException(
          "Word list size must be multiple of three words.");

    if (words.size() == 0)
      throw new MnemonicException.MnemonicLengthException("Word list is empty.");

    // Look up all the words in the list and construct the
    // concatenation of the original entropy and the checksum.
    //
    int concatLenBits = words.size() * 11;
    boolean[] concatBits = new boolean[concatLenBits];
    int wordindex = 0;
    for (String word : words) {
      // Find the words index in the wordlist.
      int ndx = Collections.binarySearch(this.wordList, word);
      if (ndx < 0) throw new MnemonicException.MnemonicWordException(word);

      // Set the next 11 bits to the value of the index.
      for (int ii = 0; ii < 11; ++ii)
        concatBits[(wordindex * 11) + ii] = (ndx & (1 << (10 - ii))) != 0;
      ++wordindex;
    }

    int checksumLengthBits = concatLenBits / 33;
    int entropyLengthBits = concatLenBits - checksumLengthBits;

    // Extract original entropy as bytes.
    byte[] entropy = new byte[entropyLengthBits / 8];
    for (int ii = 0; ii < entropy.length; ++ii)
      for (int jj = 0; jj < 8; ++jj) if (concatBits[(ii * 8) + jj]) entropy[ii] |= 1 << (7 - jj);

    // Take the digest of the entropy.
    byte[] hash = Sha256Hash.create(entropy).getBytes();
    boolean[] hashBits = bytesToBits(hash);

    // Check all the checksum bits.
    for (int i = 0; i < checksumLengthBits; ++i)
      if (concatBits[entropyLengthBits + i] != hashBits[i])
        throw new MnemonicException.MnemonicChecksumException();

    return entropy;
  }
Ejemplo n.º 2
0
  /** Convert entropy data to mnemonic word list. */
  public List<String> toMnemonic(byte[] entropy) throws MnemonicException.MnemonicLengthException {
    if (entropy.length % 4 > 0)
      throw new MnemonicException.MnemonicLengthException(
          "Entropy length not multiple of 32 bits.");

    if (entropy.length == 0)
      throw new MnemonicException.MnemonicLengthException("Entropy is empty.");

    // We take initial entropy of ENT bits and compute its
    // checksum by taking first ENT / 32 bits of its SHA256 hash.

    byte[] hash = Sha256Hash.create(entropy).getBytes();
    boolean[] hashBits = bytesToBits(hash);

    boolean[] entropyBits = bytesToBits(entropy);
    int checksumLengthBits = entropyBits.length / 32;

    // We append these bits to the end of the initial entropy.
    boolean[] concatBits = new boolean[entropyBits.length + checksumLengthBits];
    System.arraycopy(entropyBits, 0, concatBits, 0, entropyBits.length);
    System.arraycopy(hashBits, 0, concatBits, entropyBits.length, checksumLengthBits);

    // Next we take these concatenated bits and split them into
    // groups of 11 bits. Each group encodes number from 0-2047
    // which is a position in a wordlist.  We convert numbers into
    // words and use joined words as mnemonic sentence.

    ArrayList<String> words = new ArrayList<String>();
    int nwords = concatBits.length / 11;
    for (int i = 0; i < nwords; ++i) {
      int index = 0;
      for (int j = 0; j < 11; ++j) {
        index <<= 1;
        if (concatBits[(i * 11) + j]) index |= 0x1;
      }
      words.add(this.wordList.get(index));
    }

    return words;
  }
 public static ByteString hashToByteString(Sha256Hash hash) {
   return ByteString.copyFrom(hash.getBytes());
 }