code: public void write(byte b[], int off, int len) throws IOException {
          obuffer = cipher.update(b, off, len);
          if (obuffer != null) {
              output.write(obuffer);
              obuffer = null;
          }
      }
docs: Writes <code>len</code> bytes from the specified byte array
  starting at offset <code>off</code> to this output stream.
  
  @param      b     the data.
  @param      off   the start offset in the data.
  @param      len   the number of bytes to write.
  @exception  IOException  if an I/O error occurs.
  @since      JCE1.2