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emv: parse track1&2 equivalent data (#2332)

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* emv: parse track1&2 equivalent data
* emv: alternate expiry parser
* nfc: log EMV track1&2 data to trace output

Co-authored-by: gornekich <n.gorbadey@gmail.com>
Co-authored-by: あく <alleteam@gmail.com>
This commit is contained in:
Emily Trau
2023-01-27 16:10:08 +11:00
committed by GitHub
parent 8fc834090d
commit 4dc4d34d04
2 changed files with 31 additions and 7 deletions
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35
lib/nfc/protocols/emv.c
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@@ -142,21 +142,44 @@ static bool emv_decode_response(uint8_t* buff, uint16_t len, EmvApplication* app
success = true;
FURI_LOG_T(TAG, "found EMV_TAG_AFL %x (len=%d)", tag, tlen);
break;
case EMV_TAG_CARD_NUM: // Track 2 Equivalent Data. 0xD0 delimits PAN from expiry (YYMM)
case EMV_TAG_TRACK_1_EQUIV: {
char track_1_equiv[80];
memcpy(track_1_equiv, &buff[i], tlen);
track_1_equiv[tlen] = '\0';
success = true;
FURI_LOG_T(TAG, "found EMV_TAG_TRACK_1_EQUIV %x : %s", tag, track_1_equiv);
break;
}
case EMV_TAG_TRACK_2_EQUIV: {
// 0xD0 delimits PAN from expiry (YYMM)
for(int x = 1; x < tlen; x++) {
if(buff[i + x + 1] > 0xD0) {
memcpy(app->card_number, &buff[i], x + 1);
app->card_number_len = x + 1;
app->exp_year = (buff[i + x + 1] << 4) | (buff[i + x + 2] >> 4);
app->exp_month = (buff[i + x + 2] << 4) | (buff[i + x + 3] >> 4);
break;
}
}
// Convert 4-bit to ASCII representation
char track_2_equiv[41];
uint8_t track_2_equiv_len = 0;
for(int x = 0; x < tlen; x++) {
char top = (buff[i + x] >> 4) + '0';
char bottom = (buff[i + x] & 0x0F) + '0';
track_2_equiv[x * 2] = top;
track_2_equiv_len++;
if(top == '?') break;
track_2_equiv[x * 2 + 1] = bottom;
track_2_equiv_len++;
if(bottom == '?') break;
}
track_2_equiv[track_2_equiv_len] = '\0';
success = true;
FURI_LOG_T(
TAG,
"found EMV_TAG_CARD_NUM %x (len=%d)",
EMV_TAG_CARD_NUM,
app->card_number_len);
FURI_LOG_T(TAG, "found EMV_TAG_TRACK_2_EQUIV %x : %s", tag, track_2_equiv);
break;
}
case EMV_TAG_PAN:
memcpy(app->card_number, &buff[i], tlen);
app->card_number_len = tlen;