// contact all other clients (exclude self)
if (!address.equals(networkManager.getConnection().getPeer().getPeerAddress())) {
String evidence = UUID.randomUUID().toString();
evidences.put(address, evidence);
ContactPeerMessage message = new ContactPeerMessage(address, evidence);
message.setCallBackHandler(this);
// TODO this is blocking, should be parallel (asynchronous)
boolean success = messageManager.sendDirect(message, keyManager.getOwnPublicKey());
if (!success) {
responses.put(address, false);