private DeterministicKey encryptNonLeaf(
     KeyParameter aesKey,
     DeterministicKeyChain chain,
     DeterministicKey parent,
     ImmutableList<ChildNumber> path) {
   DeterministicKey key = chain.hierarchy.get(path, false, false);
   key = key.encrypt(checkNotNull(basicKeyChain.getKeyCrypter()), aesKey, parent);
   hierarchy.putKey(key);
   basicKeyChain.importKey(key);
   return key;
 }
 @Nullable
 @Override
 public KeyCrypter getKeyCrypter() {
   return basicKeyChain.getKeyCrypter();
 }