How to use org.springframework.security.crypto.codec

private static byte[] bytesUtf8(String s) {
  if (s == null) {
    return null;
  }
  return Utf8.encode(s); // need to check if Utf8.encode() runs in constant time (probably not). This may leak length of string.
}

public static boolean isBase64(byte[] bytes) {
  try {
    decode(bytes);
  }
  catch (InvalidBase64CharacterException e) {
    return false;
  }
  return true;
}

public static byte[] encode(byte[] bytes) {
  return encodeBytesToBytes(bytes, 0, bytes.length, NO_OPTIONS);
}

private String encode(byte[] digest) {
  if (this.encodeHashAsBase64) {
    return Utf8.decode(Base64.getEncoder().encode(digest));
  }
  else {
    return new String(Hex.encode(digest));
  }
}

public String encrypt(String text) {
  return new String(Hex.encode(encryptor.encrypt(Utf8.encode(text))));
}

public String decrypt(String encryptedText) {
  return Utf8.decode(encryptor.decrypt(Hex.decode(encryptedText)));
}

private byte[] decode(CharSequence encodedPassword) {
  return Hex.decode(encodedPassword);
}

  @Test(expected = IllegalArgumentException.class)
  public void isBase64RejectsInvalidLength() {
    Base64.isBase64(new byte[] { (byte) 'A' });
  }
}

private String encode(byte[] digest) {
  if (this.encodeHashAsBase64) {
    return Utf8.decode(Base64.getEncoder().encode(digest));
  }
  else {
    return new String(Hex.encode(digest));
  }
}

public static byte[] decode(byte[] bytes) {
  return decode(bytes, 0, bytes.length, NO_OPTIONS);
}

public String decrypt(String encryptedText) {
  return Utf8.decode(encryptor.decrypt(Hex.decode(encryptedText)));
}

/**
 * Constructs a standard password encoder with a secret value as well as iterations
 * and hash.
 *
 * @param secret the secret
 * @param iterations the number of iterations. Users should aim for taking about .5
 * seconds on their own system.
 * @param hashWidth the size of the hash
 */
public Pbkdf2PasswordEncoder(CharSequence secret, int iterations, int hashWidth) {
  this.secret = Utf8.encode(secret);
  this.iterations = iterations;
  this.hashWidth = hashWidth;
}

private byte[] decode(CharSequence encodedPassword) {
  return Hex.decode(encodedPassword);
}

public static byte[] encode(byte[] bytes) {
  return encodeBytesToBytes(bytes, 0, bytes.length, NO_OPTIONS);
}

@Test(expected = NullPointerException.class)
public void isBase64RejectsNull() {
  Base64.isBase64(null);
}

private String encode(byte[] digest) {
  if (this.encodeHashAsBase64) {
    return Utf8.decode(Base64.getEncoder().encode(digest));
  }
  else {
    return new String(Hex.encode(digest));
  }
}

public static boolean isBase64(byte[] bytes) {
  try {
    decode(bytes);
  }
  catch (InvalidBase64CharacterException e) {
    return false;
  }
  return true;
}

private static byte[] bytesUtf8(String s) {
  if (s == null) {
    return null;
  }
  return Utf8.encode(s); // need to check if Utf8.encode() runs in constant time (probably not). This may leak length of string.
}

public static byte[] decode(byte[] bytes) {
  return decode(bytes, 0, bytes.length, NO_OPTIONS);
}

/**
 * Constructs a standard password encoder with a secret value as well as iterations
 * and hash.
 *
 * @param secret the secret
 * @param iterations the number of iterations. Users should aim for taking about .5
 * seconds on their own system.
 * @param hashWidth the size of the hash
 */
public Pbkdf2PasswordEncoder(CharSequence secret, int iterations, int hashWidth) {
  this.secret = Utf8.encode(secret);
  this.iterations = iterations;
  this.hashWidth = hashWidth;
}