allow integrity protection for identity response

lib/include/srslte/asn1/liblte_mme.h

@@ -2939,6 +2939,8 @@ typedef struct {
 } LIBLTE_MME_ID_RESPONSE_MSG_STRUCT;
 // Functions
 LIBLTE_ERROR_ENUM liblte_mme_pack_identity_response_msg(LIBLTE_MME_ID_RESPONSE_MSG_STRUCT* id_resp,
+                                                        uint8                              sec_hdr_type,
+                                                        uint32                             count,
                                                         LIBLTE_BYTE_MSG_STRUCT*            msg);
 LIBLTE_ERROR_ENUM liblte_mme_unpack_identity_response_msg(LIBLTE_BYTE_MSG_STRUCT*            msg,
                                                           LIBLTE_MME_ID_RESPONSE_MSG_STRUCT* id_resp);

lib/src/asn1/liblte_mme.cc

@@ -6433,12 +6433,27 @@ LIBLTE_ERROR_ENUM liblte_mme_unpack_identity_request_msg(LIBLTE_BYTE_MSG_STRUCT*
     Document Reference: 24.301 v10.2.0 Section 8.2.19
 *********************************************************************/
 LIBLTE_ERROR_ENUM liblte_mme_pack_identity_response_msg(LIBLTE_MME_ID_RESPONSE_MSG_STRUCT* id_resp,
+                                                        uint8                              sec_hdr_type,
+                                                        uint32                             count,
                                                         LIBLTE_BYTE_MSG_STRUCT*            msg)
 {
   LIBLTE_ERROR_ENUM err     = LIBLTE_ERROR_INVALID_INPUTS;
   uint8*            msg_ptr = msg->msg;
 
   if (id_resp != NULL && msg != NULL) {
+    if (LIBLTE_MME_SECURITY_HDR_TYPE_PLAIN_NAS != sec_hdr_type) {
+      // Protocol Discriminator and Security Header Type
+      *msg_ptr = (sec_hdr_type << 4) | (LIBLTE_MME_PD_EPS_MOBILITY_MANAGEMENT);
+      msg_ptr++;
+
+      // MAC will be filled in later
+      msg_ptr += 4;
+
+      // Sequence Number
+      *msg_ptr = count & 0xFF;
+      msg_ptr++;
+    }
+
     // Protocol Discriminator and Security Header Type
     *msg_ptr = (LIBLTE_MME_SECURITY_HDR_TYPE_PLAIN_NAS << 4) | (LIBLTE_MME_PD_EPS_MOBILITY_MANAGEMENT);
     msg_ptr++;