import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
String plainText = PUBLIC_KEY + ":" + PRIVATE_KEY;
MessageDigest md = MessageDigest.getInstance("MD5");
byte[] hashInBytes = md.digest(password.getBytes(StandardCharsets.UTF_8));
StringBuilder builder = new StringBuilder();
for (byte bt : hashInBytes) {
builder.append(String.format("%02x", bt));
String checksum = builder.toString();