@Override
  public ChunkedMacVerification createVerification(final byte[] tag)
      throws GeneralSecurityException {
    if (tag.length < key.getOutputPrefix().size()) {
      throw new GeneralSecurityException("Tag too short");
    }
    if (!key.getOutputPrefix().equals(Bytes.copyFrom(tag, 0, key.getOutputPrefix().size()))) {
      throw new GeneralSecurityException("Wrong tag prefix");
    }
    return new ChunkedHmacVerification(key, tag);
  }
Class that provides the functionality expressed by the ChunkedMac interface with HMAC.
java_src/src/main/java/com/google/crypto/tink/mac/internal/ChunkedHmacImpl.java