/**
* Deserialize an HD Key.
*
* @param parent The parent node in the given key's deterministic hierarchy.
*/
public static DeterministicKey deserialize(
NetworkParameters params, byte[] serializedKey, @Nullable DeterministicKey parent) {
ByteBuffer buffer = ByteBuffer.wrap(serializedKey);
int header = buffer.getInt();
if (header != params.getBip32HeaderPriv() && header != params.getBip32HeaderPub())
throw new IllegalArgumentException(
"Unknown header bytes: " + toBase58(serializedKey).substring(0, 4));
boolean pub = header == params.getBip32HeaderPub();
int depth =
buffer.get() & 0xFF; // convert signed byte to positive int since depth cannot be negative
final int parentFingerprint = buffer.getInt();
final int i = buffer.getInt();
final ChildNumber childNumber = new ChildNumber(i);
ImmutableList<ChildNumber> path;
if (parent != null) {
if (parentFingerprint == 0)
throw new IllegalArgumentException("Parent was provided but this key doesn't have one");
if (parent.getFingerprint() != parentFingerprint)
throw new IllegalArgumentException("Parent fingerprints don't match");
path = HDUtils.append(parent.getPath(), childNumber);
if (path.size() != depth) throw new IllegalArgumentException("Depth does not match");
} else {
if (depth >= 1)
// We have been given a key that is not a root key, yet we lack the object representing the
// parent.
// This can happen when deserializing an account key for a watching wallet. In this case,
// we assume that
// the client wants to conceal the key's position in the hierarchy. The path is truncated
// at the
// parent's node.
path = ImmutableList.of(childNumber);
else path = ImmutableList.of();
}
byte[] chainCode = new byte[32];
buffer.get(chainCode);
byte[] data = new byte[33];
buffer.get(data);
checkArgument(!buffer.hasRemaining(), "Found unexpected data in key");
if (pub) {
return new DeterministicKey(
path,
chainCode,
new LazyECPoint(ECKey.CURVE.getCurve(), data),
parent,
depth,
parentFingerprint);
} else {
return new DeterministicKey(
path, chainCode, new BigInteger(1, data), parent, depth, parentFingerprint);
}
}
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);
}
