If the java client, have you also reviewed this code? The code I looked at only has the following imports:
import java.math.BigInteger;
import java.nio.charset.Charset;
import java.security.MessageDigest; <- SHA256 conversion routine
import java.security.SecureRandom;
import java.util.Arrays;
import java.util.Random;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;
import java.util.regex.Pattern;
I modified jean-lucs java vanity generator to make it search for short accounts. Im sure its safe since fromhim