Add CRC32 support to dynamic network management

src/network_dynamic.c

@@ -15,6 +15,7 @@
 #endif
 
 #define WITH_TAG_SIGNATURE
+// #define WITH_TAG_CRC32
 
 #define MAX_STATIC_BUFFER_SIZE 32  // TODO: Adjust with max signature size
 #define NETWORK_TLV_VERSION    0x01
@@ -26,6 +27,7 @@ enum {
     TAG_NETWORK_TICKER = 0x13,
     TAG_NETWORK_ICON = 0x14,
     TAG_SIGNATURE = 0x21,
+    TAG_CRC32 = 0x22,
 };
 
 typedef struct network_payload_s {
@@ -45,6 +47,12 @@ typedef struct {
     cx_sha256_t hash_ctx;
 } s_sig_ctx;
 #endif
+#ifdef WITH_TAG_CRC32
+typedef struct {
+    uint32_t calculated;
+    uint32_t received;
+} crc32_ctx_t;
+#endif
 
 // Global structure to temporary store the network payload APDU
 static network_payload_t g_network_payload = {0};
@@ -273,6 +281,36 @@ static bool verify_signature(s_sig_ctx *sig_ctx) {
 }
 #endif
 
+#ifdef WITH_TAG_CRC32
+/**
+ * Parse the CRC32 value.
+ *
+ * @param[in] field_len Length of the field value
+ * @param[in] offset Offset in the received buffer
+ * @param[out] crc32_received CRC32 value received
+ * @return APDU Response code
+ */
+static uint32_t parse_crc32(uint32_t field_len, uint32_t offset, uint32_t *crc32_received) {
+    if (field_len != 4) {
+        PRINTF("TAG_CRC32 Size mismatch!\n");
+        return APDU_RESPONSE_INSUFFICIENT_MEMORY;
+    }
+    *crc32_received = U4BE(g_network_payload.buf, offset);
+    return APDU_RESPONSE_OK;
+}
+/**
+ * Verify the CRC32
+ *
+ * Verify payload integrity
+ *
+ * @param[in] crc32_ctx CRC32 context
+ * @return whether it was successful
+ */
+static bool verify_crc32(crc32_ctx_t *crc32_ctx) {
+    return crc32_ctx->calculated == crc32_ctx->received;
+}
+#endif
+
 /**
  * Parse the TLV payload containing the Network configuration.
  *
@@ -290,6 +328,9 @@ static uint32_t parse_tlv(void) {
 #ifdef WITH_TAG_SIGNATURE
     s_sig_ctx sig_ctx = {0};
 #endif
+#ifdef WITH_TAG_CRC32
+    crc32_ctx_t crc32_ctx = {0};
+#endif
 
 #ifdef WITH_TAG_SIGNATURE
     // Initialize the hash context
@@ -325,6 +366,11 @@ static uint32_t parse_tlv(void) {
                 sw = parse_signature(field_len, offset, &sig_ctx);
 #endif
                 break;
+#ifdef WITH_TAG_CRC32
+            case TAG_CRC32:
+                sw = parse_crc32(field_len, offset, &crc32_ctx.received);
+                break;
+#endif
             default:
                 PRINTF("Unknown tag: %d\n", field_tag);
                 sw = APDU_RESPONSE_INVALID_DATA;
@@ -340,6 +386,13 @@ static uint32_t parse_tlv(void) {
                         (offset - tag_start_off),
                         (cx_hash_t *) &sig_ctx.hash_ctx);
         }
+#endif
+#ifdef WITH_TAG_CRC32
+        if (field_tag != TAG_CRC32) {  // crc32 wasn't computed on itself
+            crc32_ctx.calculated = cx_crc32_update(crc32_ctx.calculated,
+                                                   g_network_payload.buf + tag_start_off,
+                                                   (offset - tag_start_off));
+        }
 #endif
     }
     if (sw == APDU_RESPONSE_OK) {
@@ -348,6 +401,12 @@ static uint32_t parse_tlv(void) {
             PRINTF("Signature verification failed!\n");
             sw = APDU_RESPONSE_INVALID_DATA;
         }
+#endif
+#ifdef WITH_TAG_CRC32
+        if (verify_crc32(&crc32_ctx) == false) {
+            PRINTF("CRC32 verification failed\n");
+            sw = APDU_RESPONSE_INVALID_DATA;
+        }
 #endif
     }
     if (sw == APDU_RESPONSE_OK) {