code: public void cleanUp() {
  	int nI;
  	for (nI = 0; nI < PBOX_ENTRIES; nI++)
  	    m_pbox[nI] = 0;
  	for (nI = 0; nI < SBOX_ENTRIES; nI++)
  	    m_sbox1[nI] = m_sbox2[nI] = m_sbox3[nI] = m_sbox4[nI] = 0;
      }
docs: to clear data in the boxes before an instance is freed