Boolean return value & security aspect

Question

Again in the JCOP specification I read these lines:
In case the Java Card API method returns the boolean value, it should be immediately transferred to a short representation. Now I am having this part of the code:
boolean status = false;
          status = pin.check(buffer, (short) OFFSET_CDATA, (byte) lc);
          crypto.updateCIAPinByP2(p2, pin);
          if (!status) {
               ISOException.throwIt((short) (ISO7816Ext.SW_PIN_INCORRECT_TRIES_LEFT | pin
                         .getTriesRemaining()));
          }Is this optimal regarding to the lines at the beginning of the post. Do I need to do this:
          boolean ret = pin.check(buffer, (short) OFFSET_CDATA, (byte) lc);
          short status = ret ? (short) 0xA5A5; (short) 0x5A5A
          crypto.updateCIAPinByP2(p2, pin);
          if (status == (short) 0x5A5A) {
               ISOException.throwIt((short) (ISO7816Ext.SW_PIN_INCORRECT_TRIES_LEFT | pin
                         .getTriesRemaining()));
          }Also, the specification says that to ensure the security of the system, variables of type Boolean should not be used for storing security relevant data. Instead a short value should be used and a constant for True and a constant for the False. Should be defined and used. It is also said that these short values, representing Boolean values, shall be checked for the integrity in any kind of branching which would have an impact on security function. My question why is that so? Regarding to this text, do I need to modify anything in the first code because the returned variable is the local which value is stored in RAM?

Answer 1

In the code from the first post, in order to have the most secure code, I believe that I need to implement double check of PIN value:
public static final short TRUE = (short) 0xA5A5;
public static final short FALSE = (short) 0x5A5A;
status = pin.check(buffer, (short) dataOffset, (byte) lc) == true ? IASECCUtil.TRUE : IASECCUtil.FALSE;
if(status == IASECCUtil.TRUE) {
     status = pin.check(buffer, (short) dataOffset, (byte) lc) == true ? IASECCUtil.TRUE : IASECCUtil.FALSE;
}In this example, if at the first line, the result of the method check() is false but the fault occurs on the bus (transient fault) between the RAM and CPU register, then the program flow will be able to reach the second line that contains the check. The double check will not be affected by a second fault because the time to charge the laser is much larger. Is this correct?