belpic: Support 2K cards

Recent BELPIC cards (issued since March 2014) have a validity of 10
years (rather than 5 as before), and therefore also increased the key
size from 1024 bits to 2048 bits.

Key size can be detected by checking the applet version, for which we
have to issue a "GetCardData" command. If the applet is version 0x17 or
higher, keys are 2048 bits.

Use #defines rather than magic numbers

Keeps the code slightly more readable.

While we're at it, refactor slightly so that the code which issues the
GET CARD DATA command doesn't just keep the applet version, but also
makes other things available.

This latter in preparation of setting the serial number.

src/libopensc/card-belpic.c

@@ -127,6 +127,40 @@ static long t1, t2, tot_read = 0, tot_dur = 0, dur;
 #define BELPIC_PAD_CHAR			0xFF
 #define BELPIC_KEY_REF_NONREP		0x83
 
+/* Data in the return value for the GET CARD DATA command:
+ * All fields are one byte, except when noted otherwise.
+ *
+ * See §6.9 in
+ * https://github.com/Fedict/eid-mw/blob/master/doc/sdk/documentation/Public_Belpic_Applet_v1%207_Ref_Manual%20-%20A01.pdf
+ * for the full documentation on the GET CARD DATA command.
+ */
+// Card serial number (16 bytes)
+#define BELPIC_CARDDATA_OFF_SERIALNUM 0
+// "Component code"
+#define BELPIC_CARDDATA_OFF_COMPCODE 16
+// "OS number"
+#define BELPIC_CARDDATA_OFF_OSNUM 17
+// "OS version"
+#define BELPIC_CARDDATA_OFF_OSVER 18
+// "Softmask number"
+#define BELPIC_CARDDATA_OFF_SMNUM 19
+// "Softmask version"
+#define BELPIC_CARDDATA_OFF_SMVER 20
+// Applet version
+#define BELPIC_CARDDATA_OFF_APPLETVERS 21
+// Global OS version (2 bytes)
+#define BELPIC_CARDDATA_OFF_GL_OSVE 22
+// Applet interface version
+#define BELPIC_CARDDATA_OFF_APPINTVERS 24
+// PKCS#1 support version
+#define BELPIC_CARDDATA_OFF_PKCS1 25
+// Key exchange version
+#define BELPIC_CARDDATA_OFF_KEYX 26
+// Applet life cycle (Should always be 0F for released cards, is 07 when not issued yet)
+#define BELPIC_CARDDATA_OFF_APPLCYCLE 27
+// Full length of reply
+#define BELPIC_CARDDATA_RESP_LEN 28
+
 /* Used for a trick in select file and read binary */
 static size_t next_idx = (size_t)-1;
 
@@ -577,6 +611,42 @@ static int str2lang(sc_context_t *ctx, char *lang)
 	return -1;
 }
 
+static int get_carddata(sc_card_t *card, u8* carddata_loc, unsigned int carddataloc_len)
+{
+	sc_apdu_t apdu;
+	u8 carddata_cmd[] = { 0x80, 0xE4, 0x00, 0x00, 0x1C };
+	int r;
+
+	assert(carddataloc_len == BELPIC_CARDDATA_RESP_LEN);
+
+	r = sc_bytes2apdu(card->ctx, carddata_cmd, sizeof(carddata_cmd), &apdu);
+	if(r) {
+		sc_debug(card->ctx, SC_LOG_DEBUG_NORMAL, "bytes to APDU conversion failed: %d\n", r);
+		return r;
+	}
+
+	apdu.resp = carddata_loc;
+	apdu.resplen = carddataloc_len;
+
+	r = sc_transmit_apdu(card, &apdu);
+	if(r) {
+		sc_debug(card->ctx, SC_LOG_DEBUG_NORMAL, "GetCardData command failed: %d\n", r);
+		return r;
+	}
+
+	r = sc_check_sw(card, apdu.sw1, apdu.sw2);
+	if(r) {
+		sc_debug(card->ctx, SC_LOG_DEBUG_NORMAL, "GetCardData: card returned %d\n", r);
+		return r;
+	}
+	if(apdu.resplen < carddataloc_len) {
+		sc_debug(card->ctx, SC_LOG_DEBUG_NORMAL, "GetCardData: card returned %d bytes rather than expected %d\n", apdu.resplen, carddataloc_len);
+		return SC_ERROR_WRONG_LENGTH;
+	}
+
+	return 0;
+}
+
 #ifdef GET_LANG_FROM_CARD
 
 /* str is in lower case, the case of buf can be both, and buf is large enough */
@@ -843,9 +913,10 @@ static int belpic_init(sc_card_t *card)
 {
 	struct belpic_priv_data *priv = NULL;
 	scconf_block *conf_block;
-#ifdef BELPIC_PIN_PAD
+	u8 applet_version;
+	u8 carddata[BELPIC_CARDDATA_RESP_LEN];
+	int key_size = 1024;
 	int r;
-#endif
 
 	sc_debug(card->ctx, SC_LOG_DEBUG_NORMAL, "Belpic V%s", BELPIC_VERSION);
 #ifdef HAVE_GUI
@@ -865,7 +936,14 @@ static int belpic_init(sc_card_t *card)
 	card->drv_data = priv;
 	card->cla = 0x00;
 	if (card->type == SC_CARD_TYPE_BELPIC_EID) {
-		_sc_card_add_rsa_alg(card, 1024,
+		if((r = get_carddata(card, carddata, sizeof(carddata))) < 0) {
+			return r;
+		}
+		applet_version = carddata[BELPIC_CARDDATA_OFF_APPLETVERS];
+		if(applet_version >= 0x17) {
+			key_size = 2048;
+		}
+		_sc_card_add_rsa_alg(card, key_size,
 				     SC_ALGORITHM_RSA_PAD_PKCS1 | SC_ALGORITHM_RSA_HASH_NONE, 0);
 	}