Rework NFC EMV response parsing. Split TLV and tags per EMV spec. (#1257)
* Rework NFC EMV response parsing. Split TLV and tags per EMV spec. * Requested changes: fb -> first_byte and missed printf to FURI_LOG_T Co-authored-by: Gary <gary@x1z.net> Co-authored-by: gornekich <n.gorbadey@gmail.com>
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Gary
GitHub
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@ -10,6 +10,9 @@ const PDOLValue pdol_merchant_type = {0x9F58, {0x01}}; // Merchant type indicato
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const PDOLValue pdol_term_trans_qualifies = {
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0x9F66,
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{0x79, 0x00, 0x40, 0x80}}; // Terminal transaction qualifiers
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const PDOLValue pdol_addtnl_term_qualifies = {
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0x9F40,
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{0x79, 0x00, 0x40, 0x80}}; // Terminal transaction qualifiers
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const PDOLValue pdol_amount_authorise = {
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0x9F02,
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{0x00, 0x00, 0x00, 0x10, 0x00, 0x00}}; // Amount, authorised
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@ -30,6 +33,7 @@ const PDOLValue* const pdol_values[] = {
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&pdol_term_type,
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&pdol_merchant_type,
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&pdol_term_trans_qualifies,
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&pdol_addtnl_term_qualifies,
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&pdol_amount_authorise,
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&pdol_amount,
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&pdol_country_code,
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@ -61,6 +65,11 @@ static const uint8_t pdol_ans[] = {0x77, 0x40, 0x82, 0x02, 0x20, 0x00, 0x57, 0x1
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static void emv_trace(FuriHalNfcTxRxContext* tx_rx, const char* message) {
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if(furi_log_get_level() == FuriLogLevelTrace) {
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FURI_LOG_T(TAG, "%s", message);
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printf("TX: ");
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for(size_t i = 0; i < tx_rx->tx_bits / 8; i++) {
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printf("%02X ", tx_rx->tx_data[i]);
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}
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printf("\r\nRX: ");
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for(size_t i = 0; i < tx_rx->rx_bits / 8; i++) {
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printf("%02X ", tx_rx->rx_data[i]);
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}
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@ -68,42 +77,109 @@ static void emv_trace(FuriHalNfcTxRxContext* tx_rx, const char* message) {
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}
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}
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static uint16_t emv_parse_TLV(uint8_t* dest, uint8_t* src, uint16_t* idx) {
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uint8_t len = src[*idx + 1];
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memcpy(dest, &src[*idx + 2], len);
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*idx = *idx + len + 1;
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return len;
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}
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static bool emv_decode_search_tag_u16_r(uint16_t tag, uint8_t* buff, uint16_t* idx) {
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if((buff[*idx] << 8 | buff[*idx + 1]) == tag) {
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*idx = *idx + 3;
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return true;
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}
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return false;
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}
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bool emv_decode_ppse_response(uint8_t* buff, uint16_t len, EmvApplication* app) {
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static bool emv_decode_response(uint8_t* buff, uint16_t len, EmvApplication* app) {
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uint16_t i = 0;
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bool app_aid_found = false;
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uint16_t tag = 0, first_byte = 0;
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uint16_t tlen = 0;
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bool success = false;
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while(i < len) {
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if(buff[i] == EMV_TAG_APP_TEMPLATE) {
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uint8_t app_len = buff[++i];
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for(uint16_t j = i; j < MIN(i + app_len, len - 1); j++) {
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if(buff[j] == EMV_TAG_AID) {
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app_aid_found = true;
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app->aid_len = buff[j + 1];
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emv_parse_TLV(app->aid, buff, &j);
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} else if(buff[j] == EMV_TAG_PRIORITY) {
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emv_parse_TLV(&app->priority, buff, &j);
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}
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}
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i += app_len;
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first_byte = buff[i];
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if((first_byte & 31) == 31) { // 2-byte tag
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tag = buff[i] << 8 | buff[i + 1];
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i++;
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FURI_LOG_T(TAG, " 2-byte TLV EMV tag: %x", tag);
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} else {
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tag = buff[i];
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FURI_LOG_T(TAG, " 1-byte TLV EMV tag: %x", tag);
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}
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i++;
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tlen = buff[i];
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if((tlen & 128) == 128) { // long length value
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i++;
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tlen = buff[i];
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FURI_LOG_T(TAG, " 2-byte TLV length: %d", tlen);
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} else {
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FURI_LOG_T(TAG, " 1-byte TLV length: %d", tlen);
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}
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i++;
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if((first_byte & 32) == 32) { // "Constructed" -- contains more TLV data to parse
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FURI_LOG_T(TAG, "Constructed TLV %x", tag);
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if(!emv_decode_response(&buff[i], tlen, app)) {
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FURI_LOG_T(TAG, "Failed to decode response for %x", tag);
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// return false;
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} else {
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success = true;
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}
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} else {
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switch(tag) {
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case EMV_TAG_AID:
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app->aid_len = tlen;
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memcpy(app->aid, &buff[i], tlen);
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success = true;
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FURI_LOG_T(TAG, "found EMV_TAG_AID %x", tag);
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break;
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case EMV_TAG_PRIORITY:
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memcpy(&app->priority, &buff[i], tlen);
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success = true;
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break;
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case EMV_TAG_CARD_NAME:
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memcpy(app->name, &buff[i], tlen);
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app->name[tlen] = '\0';
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app->name_found = true;
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success = true;
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FURI_LOG_T(TAG, "found EMV_TAG_CARD_NAME %x : %s", tag, app->name);
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break;
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case EMV_TAG_PDOL:
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memcpy(app->pdol.data, &buff[i], tlen);
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app->pdol.size = tlen;
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success = true;
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FURI_LOG_T(TAG, "found EMV_TAG_PDOL %x (len=%d)", tag, tlen);
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break;
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case EMV_TAG_AFL:
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memcpy(app->afl.data, &buff[i], tlen);
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app->afl.size = tlen;
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success = true;
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FURI_LOG_T(TAG, "found EMV_TAG_AFL %x (len=%d)", tag, tlen);
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break;
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case EMV_TAG_CARD_NUM: // Track 2 Equivalent Data. 0xD0 delimits PAN from expiry (YYMM)
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for(int x = 1; x < tlen; x++) {
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if(buff[i + x + 1] > 0xD0) {
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memcpy(app->card_number, &buff[i], x + 1);
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app->card_number_len = x + 1;
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break;
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}
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}
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success = true;
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FURI_LOG_T(
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TAG,
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"found EMV_TAG_CARD_NUM %x (len=%d)",
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EMV_TAG_CARD_NUM,
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app->card_number_len);
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break;
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case EMV_TAG_PAN:
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memcpy(app->card_number, &buff[i], tlen);
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app->card_number_len = tlen;
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success = true;
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break;
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case EMV_TAG_EXP_DATE:
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app->exp_year = buff[i];
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app->exp_month = buff[i + 1];
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success = true;
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break;
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case EMV_TAG_CURRENCY_CODE:
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app->currency_code = (buff[i] << 8 | buff[i + 1]);
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success = true;
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break;
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case EMV_TAG_COUNTRY_CODE:
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app->country_code = (buff[i] << 8 | buff[i + 1]);
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success = true;
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break;
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}
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}
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i += tlen;
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}
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return app_aid_found;
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return success;
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}
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bool emv_select_ppse(FuriHalNfcTxRxContext* tx_rx, EmvApplication* app) {
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@ -124,7 +200,7 @@ bool emv_select_ppse(FuriHalNfcTxRxContext* tx_rx, EmvApplication* app) {
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FURI_LOG_D(TAG, "Send select PPSE");
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if(furi_hal_nfc_tx_rx(tx_rx, 300)) {
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emv_trace(tx_rx, "Select PPSE answer:");
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if(emv_decode_ppse_response(tx_rx->rx_data, tx_rx->rx_bits / 8, app)) {
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if(emv_decode_response(tx_rx->rx_data, tx_rx->rx_bits / 8, app)) {
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app_aid_found = true;
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} else {
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FURI_LOG_E(TAG, "Failed to parse application");
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@ -136,28 +212,6 @@ bool emv_select_ppse(FuriHalNfcTxRxContext* tx_rx, EmvApplication* app) {
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return app_aid_found;
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}
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static bool emv_decode_select_app_response(uint8_t* buff, uint16_t len, EmvApplication* app) {
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uint16_t i = 0;
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bool decode_success = false;
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while(i < len) {
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if(buff[i] == EMV_TAG_CARD_NAME) {
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uint8_t name_len = buff[i + 1];
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emv_parse_TLV((uint8_t*)app->name, buff, &i);
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app->name[name_len] = '\0';
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app->name_found = true;
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decode_success = true;
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} else if(((buff[i] << 8) | buff[i + 1]) == EMV_TAG_PDOL) {
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i++;
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app->pdol.size = emv_parse_TLV(app->pdol.data, buff, &i);
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decode_success = true;
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}
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i++;
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}
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return decode_success;
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}
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bool emv_select_app(FuriHalNfcTxRxContext* tx_rx, EmvApplication* app) {
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bool select_app_success = false;
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const uint8_t emv_select_header[] = {
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@ -181,7 +235,7 @@ bool emv_select_app(FuriHalNfcTxRxContext* tx_rx, EmvApplication* app) {
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FURI_LOG_D(TAG, "Start application");
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if(furi_hal_nfc_tx_rx(tx_rx, 300)) {
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emv_trace(tx_rx, "Start application answer:");
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if(emv_decode_select_app_response(tx_rx->rx_data, tx_rx->rx_bits / 8, app)) {
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if(emv_decode_response(tx_rx->rx_data, tx_rx->rx_bits / 8, app)) {
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select_app_success = true;
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} else {
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FURI_LOG_E(TAG, "Failed to read PAN or PDOL");
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@ -226,22 +280,6 @@ static uint16_t emv_prepare_pdol(APDU* dest, APDU* src) {
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return dest->size;
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}
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static bool emv_decode_get_proc_opt(uint8_t* buff, uint16_t len, EmvApplication* app) {
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bool card_num_read = false;
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for(uint16_t i = 0; i < len; i++) {
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if(buff[i] == EMV_TAG_CARD_NUM) {
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app->card_number_len = 8;
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memcpy(app->card_number, &buff[i + 2], app->card_number_len);
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card_num_read = true;
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} else if(buff[i] == EMV_TAG_AFL) {
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app->afl.size = emv_parse_TLV(app->afl.data, buff, &i);
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}
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}
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return card_num_read;
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}
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static bool emv_get_processing_options(FuriHalNfcTxRxContext* tx_rx, EmvApplication* app) {
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bool card_num_read = false;
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const uint8_t emv_gpo_header[] = {0x80, 0xA8, 0x00, 0x00};
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@ -264,8 +302,10 @@ static bool emv_get_processing_options(FuriHalNfcTxRxContext* tx_rx, EmvApplicat
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FURI_LOG_D(TAG, "Get proccessing options");
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if(furi_hal_nfc_tx_rx(tx_rx, 300)) {
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emv_trace(tx_rx, "Get processing options answer:");
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if(emv_decode_get_proc_opt(tx_rx->rx_data, tx_rx->rx_bits / 8, app)) {
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card_num_read = true;
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if(emv_decode_response(tx_rx->rx_data, tx_rx->rx_bits / 8, app)) {
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if(app->card_number_len > 0) {
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card_num_read = true;
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}
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}
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} else {
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FURI_LOG_E(TAG, "Failed to get processing options");
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@ -274,31 +314,6 @@ static bool emv_get_processing_options(FuriHalNfcTxRxContext* tx_rx, EmvApplicat
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return card_num_read;
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}
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static bool emv_decode_read_sfi_record(uint8_t* buff, uint16_t len, EmvApplication* app) {
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bool pan_parsed = false;
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for(uint16_t i = 0; i < len; i++) {
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if(buff[i] == EMV_TAG_PAN) {
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if(buff[i + 1] == 8 || buff[i + 1] == 10) {
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app->card_number_len = buff[i + 1];
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memcpy(app->card_number, &buff[i + 2], app->card_number_len);
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pan_parsed = true;
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}
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} else if(emv_decode_search_tag_u16_r(EMV_TAG_EXP_DATE, buff, &i)) {
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app->exp_year = buff[i++];
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app->exp_month = buff[i++];
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} else if(emv_decode_search_tag_u16_r(EMV_TAG_CURRENCY_CODE, buff, &i)) {
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app->currency_code = (buff[i] << 8) | buff[i + 1];
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i += 2;
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} else if(emv_decode_search_tag_u16_r(EMV_TAG_COUNTRY_CODE, buff, &i)) {
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app->country_code = (buff[i] << 8) | buff[i + 1];
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i += 1;
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}
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}
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return pan_parsed;
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}
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static bool emv_read_sfi_record(
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FuriHalNfcTxRxContext* tx_rx,
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EmvApplication* app,
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@ -320,7 +335,7 @@ static bool emv_read_sfi_record(
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if(furi_hal_nfc_tx_rx(tx_rx, 300)) {
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emv_trace(tx_rx, "SFI record:");
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if(emv_decode_read_sfi_record(tx_rx->rx_data, tx_rx->rx_bits / 8, app)) {
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if(emv_decode_response(tx_rx->rx_data, tx_rx->rx_bits / 8, app)) {
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card_num_read = true;
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}
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} else {
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