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openairinterface5g/openair3/SECU/key_nas_deriver.c
T
2023-05-26 12:35:33 +02:00

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7.3 KiB
C

/*
* Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The OpenAirInterface Software Alliance licenses this file to You under
* the OAI Public License, Version 1.1 (the "License"); you may not use this file
* except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.openairinterface.org/?page_id=698
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*-------------------------------------------------------------------------------
* For more information about the OpenAirInterface (OAI) Software Alliance:
* contact@openairinterface.org
*/
#include "aes_128.h"
#include "aes_128_cbc_cmac.h"
#include "common/utils/assertions.h"
#include "common/utils/LOG/log.h"
#include "kdf.h"
#include "key_nas_deriver.h"
#include "nas_stream_eea1.h"
#include "nas_stream_eea2.h"
#include "nas_stream_eia1.h"
#include "nas_stream_eia2.h"
#include "secu_defs.h"
#include "snow3g.h"
#include <arpa/inet.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#define FC_KENB (0x11)
#define FC_NH (0x12)
#define FC_KENB_STAR (0x13)
/* 33401 #A.7 Algorithm for key derivation function.
* This FC should be used for:
* - NAS Encryption algorithm
* - NAS Integrity algorithm
* - RRC Encryption algorithm
* - RRC Integrity algorithm
* - User Plane Encryption algorithm
*/
#define FC_ALG_KEY_DER (0x15)
#define FC_KASME_TO_CK (0x16)
#define NR_FC_ALG_KEY_DER (0x69)
#define NR_FC_ALG_KEY_NG_RAN_STAR_DER (0x70)
// #define SECU_DEBUG 1
static void derive_key_common(algorithm_type_dist_t alg_type, uint8_t alg_id, const uint8_t kasme[32], uint8_t FC, uint8_t out[32])
{
uint8_t s[7];
#if defined(SECU_DEBUG)
int i;
#endif
/* FC */
s[0] = FC;
/* P0 = algorithm type distinguisher */
s[1] = (uint8_t)(alg_type & 0xFF);
/* L0 = length(P0) = 1 */
s[2] = 0x00;
s[3] = 0x01;
/* P1 */
s[4] = alg_id;
/* L1 = length(P1) = 1 */
s[5] = 0x00;
s[6] = 0x01;
#if defined(SECU_DEBUG)
printf("%s FC %d nas_alg_type distinguisher %d nas_enc_alg_identity %d\n", __FUNCTION__, FC_ALG_KEY_DER, alg_type, alg_id);
for (i = 0; i < 7; i ++) {
printf("0x%02x ", s[i]);
}
printf("\n");
#endif
byte_array_t data = {.len = 7, .buf = s};
kdf(kasme, data, 32, out);
}
/*!
* @brief Derive the kNASenc from kasme and perform truncate on the generated key to
* reduce his size to 128 bits. Definition of the derivation function can
* be found in 3GPP TS.33401 #A.7
* @param[in] nas_alg_type NAS algorithm distinguisher
* @param[in] nas_enc_alg_id NAS encryption/integrity algorithm identifier.
* Possible values are:
* - 0 for EIA0 algorithm (Null Integrity Protection algorithm)
* - 1 for 128-EIA1 SNOW 3G
* - 2 for 128-EIA2 AES
* @param[in] kasme Key for MME as provided by AUC
* @param[out] knas Pointer to reference where output of KDF will be stored.
*/
void derive_key_nas(algorithm_type_dist_t alg_type, uint8_t alg_id, const uint8_t kasme[32], uint8_t knas[32])
{
derive_key_common(alg_type, alg_id, kasme, FC_ALG_KEY_DER, knas);
}
void nr_derive_key(algorithm_type_dist_t alg_type, uint8_t alg_id, const uint8_t key[32], uint8_t out[16])
{
uint8_t tmp[32] = {0};
derive_key_common(alg_type, alg_id, key, NR_FC_ALG_KEY_DER, tmp);
// Only the last 16 bytes are needed in 5G
memcpy(out, &tmp[16], 16);
}
/*!
* @brief Derive the keys from key and perform truncate on the generated key to
* reduce his size to 128 bits. Definition of the derivation function can
* be found in 3GPP TS.33401 #A.7
* @param[in] alg_type Algorithm distinguisher
* @param[in] alg_id Algorithm identifier.
* Possible values are:
* - 0 for EIA0 algorithm (Null Integrity Protection algorithm)
* - 1 for 128-EIA1 SNOW 3G
* - 2 for 128-EIA2 AES
* @param[in] key The top key used to derive other subkeys
* @param[out] out Pointer to reference where output of KDF will be stored.
* NOTE: knas is dynamically allocated by the KDF function
*/
#ifndef NAS_UE
void derive_keNB(const uint8_t kasme[32], const uint32_t nas_count, uint8_t *keNB)
{
uint8_t s[7] = {0};
// FC
s[0] = FC_KENB;
// P0 = Uplink NAS count
s[1] = (nas_count & 0xff000000) >> 24;
s[2] = (nas_count & 0x00ff0000) >> 16;
s[3] = (nas_count & 0x0000ff00) >> 8;
s[4] = (nas_count & 0x000000ff);
// Length of NAS count
s[5] = 0x00;
s[6] = 0x04;
byte_array_t data = {.buf = s, .len = 7};
kdf(kasme, data, 32, keNB);
}
#endif
void derive_keNB_star(const uint8_t *kenb_32,
const uint16_t pci,
const uint32_t earfcn_dl,
const bool is_rel8_only,
uint8_t *kenb_star)
{
// see 33.401 section A.5 KeNB* derivation function
uint8_t s[10] = {0};
byte_array_t data = {.buf = s};
// FC = 0x13
s[0] = FC_KENB_STAR;
// P0 = PCI (target physical cell id)
s[1] = (pci & 0x0000ff00) >> 8;
s[2] = (pci & 0x000000ff);
// L0 = length of PCI (i.e. 0x00 0x02)
s[3] = 0x00;
s[4] = 0x02;
// P1 = EARFCN-DL (target physical cell downlink frequency)
if (is_rel8_only) {
s[5] = (earfcn_dl & 0x0000ff00) >> 8;
s[6] = (earfcn_dl & 0x000000ff);
s[7] = 0x00;
s[8] = 0x02;
data.len = 9;
} else {
s[5] = (earfcn_dl & 0x00ff0000) >> 16;
s[6] = (earfcn_dl & 0x0000ff00) >> 8;
s[7] = (earfcn_dl & 0x000000ff);
s[8] = 0x00;
s[9] = 0x03;
data.len = 10;
}
kdf(kenb_32, data, 32, kenb_star);
// L1 length of EARFCN-DL (i.e. L1 = 0x00 0x02 if EARFCN-DL is between 0 and 65535, and L1 = 0x00 0x03 if EARFCN-DL is between
// 65536 and 262143) NOTE: The length of EARFCN-DL cannot be generally set to 3 bytes for backward compatibility reasons: A Rel-8
// entity (UE or eNB) would always assume an input parameter length of 2 bytes for the EARFCN-DL. This
// would lead to different derived keys if another entity assumed an input parameter length of 3 bytes for the
// EARFCN-DL.
}
void nr_derive_key_ng_ran_star(uint16_t pci, uint64_t nr_arfcn_dl, const uint8_t key[32], uint8_t *key_ng_ran_star)
{
uint8_t s[10] = {0};
/* FC */
s[0] = NR_FC_ALG_KEY_NG_RAN_STAR_DER;
/* P0 = PCI */
s[1] = (pci & 0x0000ff00) >> 8;
s[2] = (pci & 0x000000ff);
/* L0 = length(P0) = 2 */
s[3] = 0x00;
s[4] = 0x02;
/* P1 = NR ARFCN */
s[5] = (nr_arfcn_dl & 0x00ff0000) >> 16;
s[6] = (nr_arfcn_dl & 0x0000ff00) >> 8;
s[7] = (nr_arfcn_dl & 0x000000ff);
/* L1 = length(P1) = 3 */
s[8] = 0x00;
s[9] = 0x03;
byte_array_t data = {.buf = s, .len = 10};
const uint32_t len_key = 32;
kdf(key, data, len_key, key_ng_ran_star);
}
void derive_skgNB(const uint8_t *keNB, const uint16_t sk_counter, uint8_t *skgNB)
{
uint8_t s[5] = {0};
/* FC is 0x1c (see 3gpp 33.401 annex A.15) */
s[0] = 0x1c;
/* put sk_counter */
s[1] = (sk_counter >> 8) & 0xff;
s[2] = sk_counter & 0xff;
/* put length of sk_counter (2) */
s[3] = 0x00;
s[4] = 0x02;
byte_array_t data = {.buf = s, .len = 5};
kdf(keNB, data, 32, skgNB);
}