Address integrity failure after UE reconnects from RRC IDLE

After a new connection from RRC IDLE, an integrity failure occurs. This
commit is addressing this issue to pass the integrity check.

* Reset ciphering and integrity algorithms when going into RRC IDLE

* Use uplink NAS COUNT in Registration Request for initial KgNB derivation
  * Temporarily deriving UP protection keys in Registration Request
  * Note: AS SMC handling should be done according to 33.501 §6.8.1.1.2.2

openair2/RRC/NR_UE/rrc_UE.c

@@ -2562,6 +2562,8 @@ void nr_rrc_going_to_IDLE(NR_UE_RRC_INST_t *rrc,
 
   // discard the keys (only kgnb is stored)
   memset(rrc->kgnb, 0, sizeof(rrc->kgnb));
+  rrc->integrityProtAlgorithm = 0;
+  rrc->cipheringAlgorithm = 0;
 
   // release all radio resources, including release of the RLC entity,
   // the MAC configuration and the associated PDCP entity

openair3/NAS/NR_UE/nr_nas_msg.c

@@ -663,6 +663,12 @@ void generateRegistrationRequest(as_nas_info_t *initialNasMsg, nr_ue_nas_t *nas,
       nasmessagecontainercontents->length = mm_msg_encode(&full_mm, nasmessagecontainercontents->value, size_nct);
       size += (nasmessagecontainercontents->length + 2);
       rr->presencemask |= REGISTRATION_REQUEST_NAS_MESSAGE_CONTAINER_PRESENT;
+      // Workaround to pass integrity in RRC_IDLE
+      uint8_t *kamf = nas->security.kamf;
+      uint8_t *kgnb = nas->security.kgnb;
+      derive_kgnb(kamf, nas->security.nas_count_ul, kgnb);
+      int nas_itti_kgnb_refresh_req(instance_t instance, const uint8_t kgnb[32]);
+      nas_itti_kgnb_refresh_req(nas->UE_id, nas->security.kgnb);
     }
     // Allocate buffer (including NAS message container size)
     initialNasMsg->nas_data = malloc_or_fail(size * sizeof(*initialNasMsg->nas_data));