From d06790fcf2ff7ec048b39071a6b04140cd55d99e Mon Sep 17 00:00:00 2001
From: Guido Casati <hello@guidocasati.com>
Date: Tue, 29 Apr 2025 22:50:04 +0200
Subject: [PATCH] Move derive_kgnb to key_nas_deriver lib

---
 openair3/NAS/NR_UE/nr_nas_msg.c | 36 +--------------------------------
 openair3/SECU/key_nas_deriver.c | 32 +++++++++++++++++++++++++++++
 openair3/SECU/key_nas_deriver.h |  2 ++
 3 files changed, 35 insertions(+), 35 deletions(-)

diff --git a/openair3/NAS/NR_UE/nr_nas_msg.c b/openair3/NAS/NR_UE/nr_nas_msg.c
index d152a5d4a3..4c5d6fb717 100644
--- a/openair3/NAS/NR_UE/nr_nas_msg.c
+++ b/openair3/NAS/NR_UE/nr_nas_msg.c
@@ -71,6 +71,7 @@
 #include "fgmm_service_accept.h"
 #include "fgmm_service_reject.h"
 #include "ds/byte_array.h"
+#include "key_nas_deriver.h"
 
 #define MAX_NAS_UE 4
 
@@ -444,41 +445,6 @@ void derive_knas(algorithm_type_dist_t nas_alg_type, uint8_t nas_alg_id, uint8_t
   memcpy(knas, out + 16, 16);
 }
 
-static void derive_kgnb(uint8_t kamf[32], uint32_t count, uint8_t *kgnb)
-{
-  /* Compute the KDF input parameter
-   * S = FC(0x6E) || UL NAS Count || 0x00 0x04 || 0x01 || 0x00 0x01
-   */
-  uint8_t input[32] = {0};
-  //    uint16_t length    = 4;
-  //    int      offset    = 0;
-
-  LOG_TRACE(INFO, "%s  with count= %d", __FUNCTION__, count);
-  memset(input, 0, 32);
-  input[0] = 0x6E;
-  // P0
-  input[1] = count >> 24;
-  input[2] = (uint8_t)(count >> 16);
-  input[3] = (uint8_t)(count >> 8);
-  input[4] = (uint8_t)count;
-  // L0
-  input[5] = 0;
-  input[6] = 4;
-  // P1
-  input[7] = 0x01;
-  // L1
-  input[8] = 0;
-  input[9] = 1;
-
-  byte_array_t data = {.buf = input, .len = 10};
-  kdf(kamf, data, 32, kgnb);
-
-  printf("kgnb : ");
-  for (int pp = 0; pp < 32; pp++)
-    printf("%02x ", kgnb[pp]);
-  printf("\n");
-}
-
 static void derive_ue_keys(uint8_t *buf, nr_ue_nas_t *nas)
 {
   uint8_t ak[6];
diff --git a/openair3/SECU/key_nas_deriver.c b/openair3/SECU/key_nas_deriver.c
index 1011eeb357..ec6da5e411 100644
--- a/openair3/SECU/key_nas_deriver.c
+++ b/openair3/SECU/key_nas_deriver.c
@@ -139,6 +139,38 @@ void nr_derive_key(algorithm_type_dist_t alg_type, uint8_t alg_id, const uint8_t
  * NOTE: knas is dynamically allocated by the KDF function
  */
 
+/** @brief KgNB derivation (A.9 3GPP TS 33.501) */
+void derive_kgnb(uint8_t kamf[32], uint32_t count, uint8_t *kgnb)
+{
+  /* Compute the KDF input parameter
+   * S = FC(0x6E) || UL NAS Count || 0x00 0x04 || 0x01 || 0x00 0x01
+   */
+  uint8_t input[32] = {0};
+
+  input[0] = 0x6E;
+  // P0
+  input[1] = count >> 24;
+  input[2] = (uint8_t)(count >> 16);
+  input[3] = (uint8_t)(count >> 8);
+  input[4] = (uint8_t)count;
+  // L0
+  input[5] = 0;
+  input[6] = 4;
+  // P1
+  input[7] = 0x01;
+  // L1
+  input[8] = 0;
+  input[9] = 1;
+
+  byte_array_t data = {.buf = input, .len = 10};
+  kdf(kamf, data, 32, kgnb);
+
+  printf("kgnb : ");
+  for (int pp = 0; pp < 32; pp++)
+    printf("%02x ", kgnb[pp]);
+  printf("\n");
+}
+
 void derive_keNB(const uint8_t kasme[32], const uint32_t nas_count, uint8_t *keNB)
 {
   uint8_t s[7] = {0};
diff --git a/openair3/SECU/key_nas_deriver.h b/openair3/SECU/key_nas_deriver.h
index 4e84c5f3be..99c5b20b51 100644
--- a/openair3/SECU/key_nas_deriver.h
+++ b/openair3/SECU/key_nas_deriver.h
@@ -14,6 +14,8 @@ typedef enum {
   UP_INT_ALG = 0x06
 } algorithm_type_dist_t;
 
+void derive_kgnb(uint8_t kamf[32], uint32_t count, uint8_t *kgnb);
+
 void derive_keNB(const uint8_t kasme[32], const uint32_t nas_count, uint8_t *keNB);
 
 void derive_keNB_star(const uint8_t *kenb_32,