/**
* Pre-generate enough keys to reach the lookahead size, but only if there are more than the
* lookaheadThreshold to be generated, so that the Bloom filter does not have to be regenerated
* that often.
*
* <p>The returned mutable list of keys must be inserted into the basic key chain.
*/
private List<DeterministicKey> maybeLookAhead(
DeterministicKey parent, int issued, int lookaheadSize, int lookaheadThreshold) {
checkState(lock.isHeldByCurrentThread());
final int numChildren = hierarchy.getNumChildren(parent.getPath());
final int needed = issued + lookaheadSize + lookaheadThreshold - numChildren;
if (needed <= lookaheadThreshold) return new ArrayList<DeterministicKey>();
log.info(
"{} keys needed for {} = {} issued + {} lookahead size + {} lookahead threshold - {} num children",
needed,
parent.getPathAsString(),
issued,
lookaheadSize,
lookaheadThreshold,
numChildren);
List<DeterministicKey> result = new ArrayList<DeterministicKey>(needed);
long now = System.currentTimeMillis();
int nextChild = numChildren;
for (int i = 0; i < needed; i++) {
DeterministicKey key = HDKeyDerivation.deriveThisOrNextChildKey(parent, nextChild);
key = key.getPubOnly();
hierarchy.putKey(key);
result.add(key);
nextChild = key.getChildNumber().num() + 1;
}
log.info("Took {} msec", System.currentTimeMillis() - now);
return result;
}
private void checkForBitFlip(DeterministicKey k) {
DeterministicKey parent = checkNotNull(k.getParent());
byte[] rederived =
HDKeyDerivation.deriveChildKeyBytesFromPublic(
parent, k.getChildNumber(), HDKeyDerivation.PublicDeriveMode.WITH_INVERSION)
.keyBytes;
byte[] actual = k.getPubKey();
if (!Arrays.equals(rederived, actual))
throw new IllegalStateException(
String.format(
"Bit-flip check failed: %s vs %s",
Arrays.toString(rederived), Arrays.toString(actual)));
}
DeterministicKeyChain(DeterministicSeed seed, @Nullable KeyCrypter crypter) {
this.seed = seed;
basicKeyChain = new BasicKeyChain(crypter);
if (!seed.isEncrypted()) {
rootKey = HDKeyDerivation.createMasterPrivateKey(checkNotNull(seed.getSeedBytes()));
rootKey.setCreationTimeSeconds(seed.getCreationTimeSeconds());
initializeHierarchyUnencrypted(rootKey);
}
// Else...
// We can't initialize ourselves with just an encrypted seed, so we expected deserialization
// code to do the
// rest of the setup (loading the root key).
}
private BigInteger derivePrivateKeyDownwards(
DeterministicKey cursor, byte[] parentalPrivateKeyBytes) {
DeterministicKey downCursor =
new DeterministicKey(
cursor.childNumberPath,
cursor.chainCode,
cursor.pub,
new BigInteger(1, parentalPrivateKeyBytes),
cursor.parent);
// Now we have to rederive the keys along the path back to ourselves. That path can be found by
// just truncating
// our path with the length of the parents path.
ImmutableList<ChildNumber> path =
childNumberPath.subList(cursor.getPath().size(), childNumberPath.size());
for (ChildNumber num : path) {
downCursor = HDKeyDerivation.deriveChildKey(downCursor, num);
}
// downCursor is now the same key as us, but with private key bytes.
checkState(downCursor.pub.equals(pub));
return checkNotNull(downCursor.priv);
}
/**
* Derives a child at the given index using hardened derivation. Note: <code>index</code> is not
* the "i" value. If you want the softened derivation, then use instead <code>
* HDKeyDerivation.deriveChildKey(this, new ChildNumber(child, false))</code>.
*/
public DeterministicKey derive(int child) {
return HDKeyDerivation.deriveChildKey(this, new ChildNumber(child, true));
}
