cp: Remove unused flag PD_FLAG_HAS_SCBK

PD_FLAG_HAS_SCBK was used to decide if the SCBK must be preserved when
secure channel is initialized. This was from an era where we had master
key based key derivation where the SCBK was derived.

Since master-key has long been depreciated and subsequently removed, we
can get rid of that flag too.

Signed-off-by: Siddharth Chandrasekaran <sidcha.dev@gmail.com>

Author: sidcha

src/osdp_common.h

@@ -270,10 +270,9 @@ union osdp_ephemeral_data {
 #define PD_FLAG_CHN_SHARED     BIT(9)  /* PD's channel is shared */
 #define PD_FLAG_PKT_SKIP_MARK  BIT(10) /* OPT_OSDP_SKIP_MARK_BYTE */
 #define PD_FLAG_PKT_HAS_MARK   BIT(11) /* Packet has mark byte */
-#define PD_FLAG_HAS_SCBK       BIT(12) /* PD has a dedicated SCBK */
-#define PD_FLAG_SC_DISABLED    BIT(13) /* master_key=NULL && scbk=NULL */
-#define PD_FLAG_PKT_BROADCAST  BIT(14) /* this packet was addressed to 0x7F */
-#define PD_FLAG_CP_USE_CRC     BIT(15) /* CP uses CRC-16 instead of checksum */
+#define PD_FLAG_SC_DISABLED    BIT(12) /* master_key=NULL && scbk=NULL */
+#define PD_FLAG_PKT_BROADCAST  BIT(13) /* this packet was addressed to 0x7F */
+#define PD_FLAG_CP_USE_CRC     BIT(14) /* CP uses CRC-16 instead of checksum */
 
 /* PD Init flags */
 #define PD_FLAG_ENFORCE_SECURE  BIT(24) /* See: OSDP_FLAG_ENFORCE_SECURE */

src/osdp_cp.c

@@ -1558,7 +1558,6 @@ static int cp_add_pd(struct osdp *ctx, int num_pd, const osdp_pd_info_t *info_li
 		memcpy(&pd->channel, &info->channel, sizeof(struct osdp_channel));
 		if (info->scbk != NULL) {
 			memcpy(pd->sc.scbk, info->scbk, 16);
-			SET_FLAG(pd, PD_FLAG_HAS_SCBK);
 			CLEAR_FLAG(pd, PD_FLAG_SC_DISABLED);
 		} else if (is_enforce_secure(pd)) {
 			LOG_PRINT("SCBK must be passed for each PD when"

src/osdp_sc.c

@@ -219,17 +219,13 @@ int osdp_compute_mac(struct osdp_pd *pd, int is_cmd,
 void osdp_sc_setup(struct osdp_pd *pd)
 {
 	uint8_t scbk[16];
-	bool preserve_scbk = is_pd_mode(pd) || ISSET_FLAG(pd, PD_FLAG_HAS_SCBK);
 
 	osdp_crypt_setup();
 
-	if (preserve_scbk) {
-		memcpy(scbk, pd->sc.scbk, 16);
-	}
+	memcpy(scbk, pd->sc.scbk, 16);
 	memset(&pd->sc, 0, sizeof(struct osdp_secure_channel));
-	if (preserve_scbk) {
-		memcpy(pd->sc.scbk, scbk, 16);
-	}
+	memcpy(pd->sc.scbk, scbk, 16);
+
 	if (is_pd_mode(pd)) {
 		pd->sc.pd_client_uid[0] = BYTE_0(pd->id.vendor_code);
 		pd->sc.pd_client_uid[1] = BYTE_1(pd->id.vendor_code);