code: private boolean verifyHelloMessage(byte[] helloMsg) {
  		if (sdpHelloHashReceived != null) {
  			String hash = calculateSHA256Hash(helloMsg, 0, helloMsg.length);
  			boolean hashesMatched = hash.toUpperCase().equals(
  					sdpHelloHashReceived.toUpperCase());
  			if (platform.getLogger().isEnabled()) {
  				if (hashesMatched) {
  					logString("verifyHelloMessage() Hello hash verified OK.");
  				} else {
  					logString("verifyHelloMessage() Hello hash does NOT match  hash= '"
  							+ hash
  							+ "' expected (SDP) = '"
  							+ sdpHelloHashReceived + "'");
  				}
  			}
  			return hashesMatched;
  		} else {
  			return true;
  		}
  	}
docs: Verify whether the contents of the Hello message received has not been
  altered, by matching with the SHA256 hash received in SDP exchange.
  
  @param helloMsg
  Contents of the Hello message received
  @return True if the Hello message is verified, false if not.