sniff: add checksum verification for ATR and PPS
a checksum error is only signaled in the USB message with the
corresponding flag.
Change-Id: I277868267c3199eea216ab47bdd09fb2fb944b06
diff --git a/firmware/libcommon/source/sniffer.c b/firmware/libcommon/source/sniffer.c
index c58b047..f99c25a 100644
--- a/firmware/libcommon/source/sniffer.c
+++ b/firmware/libcommon/source/sniffer.c
@@ -394,6 +394,7 @@
static uint8_t atr_hist_len = 0; /* store the number of expected historical bytes */
static uint8_t y = 0; /* last mask of the upcoming TA, TB, TC, TD interface bytes */
static uint8_t i = 0; /* interface byte subgroup number */
+ static uint32_t flags = 0; /* error flag */
/* sanity check */
if (ISO7816_S_IN_ATR != iso_state) {
@@ -411,6 +412,7 @@
/* handle ATR byte depending on current state */
switch (atr_state) {
case ATR_S_WAIT_TS: /* see ISO/IEC 7816-3:2006 section 8.1 */
+ flags = 0;
switch (byte) {
case 0x23: /* direct convention used, but decoded using inverse convention (a parity error should also have occurred) */
case 0x30: /* inverse convention used, but decoded using direct convention (a parity error should also have occurred) */
@@ -480,8 +482,21 @@
break;
}
case ATR_S_WAIT_TCK: /* see ISO/IEC 7816-3:2006 section 8.2.5 */
- /* we could verify the checksum, but we are just here to sniff */
- usb_send_atr(0); /* send ATR to host software using USB */
+ /* verify checksum if present */
+ if (ATR_S_WAIT_TCK == atr_state) {
+ uint8_t ui;
+ uint8_t checksum = 0;
+ for (ui = 1; ui < atr_i; atr_i++) {
+ checksum ^= atr[ui];
+ }
+ if (checksum) {
+ flags |= SNIFF_DATA_FLAG_ERROR_CHECKSUM;
+ /* We still consider the data as valid (e.g. for WT) even is the checksum is wrong.
+ * It is up to the reader to handle this error (e.g. by resetting)
+ */
+ }
+ }
+ usb_send_atr(flags); /* send ATR to host software using USB */
change_state(ISO7816_S_WAIT_TPDU); /* go to next state */
break;
default:
@@ -551,6 +566,7 @@
static void process_byte_pps(uint8_t byte)
{
uint8_t *pps_cur; /* current PPS (request or response) */
+ static uint32_t flags = 0; /* error flag */
/* sanity check */
if (ISO7816_S_IN_PPS_REQ == iso_state) {
@@ -565,6 +581,7 @@
/* handle PPS byte depending on current state */
switch (pps_state) { /* see ISO/IEC 7816-3:2006 section 9.2 */
case PPS_S_WAIT_PPSS: /*!< initial byte */
+ flags = 0;
if (0xff) {
pps_cur[0] = byte;
pps_state = PPS_S_WAIT_PPS0; /* go to next state */
@@ -613,8 +630,11 @@
check ^= pps_cur[4];
}
check ^= pps_cur[5];
+ if (check) {
+ flags |= SNIFF_DATA_FLAG_ERROR_CHECKSUM;
+ }
pps_state = PPS_S_WAIT_END;
- usb_send_pps(0); /* send PPS to host software using USB */
+ usb_send_pps(flags); /* send PPS to host software using USB */
if (ISO7816_S_IN_PPS_REQ == iso_state) {
if (0 == check) { /* checksum is valid */
change_state(ISO7816_S_WAIT_PPS_RSP); /* go to next state */