59 lines
1.4 KiB
C
59 lines
1.4 KiB
C
#include <stdlib.h>
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#include <stdio.h>
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#include <stdint.h>
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#include <string.h>
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#include "security_types.h"
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#include "secu_defs.h"
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/*!
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* @brief Derive the kNASenc from kasme and perform truncate on the generated key to
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* reduce his size to 128 bits. Definition of the derivation function can
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* be found in 3GPP TS.33401 #A.7
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* @param[in] nas_alg_type NAS algorithm distinguisher
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* @param[in] nas_enc_alg_id NAS encryption/integrity algorithm identifier.
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* Possible values are:
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* - 0 for EIA0 algorithm (Null Integrity Protection algorithm)
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* - 1 for 128-EIA1 SNOW 3G
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* - 2 for 128-EIA2 AES
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* @param[in] kasme Key for MME as provided by AUC
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* @param[out] knas Pointer to reference where output of KDF will be stored.
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* NOTE: knas is dynamically allocated by the KDF function
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*/
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int derive_key_nas(algorithm_type_dist_t nas_alg_type, uint8_t nas_enc_alg_id,
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const uint8_t kasme[32], uint8_t **knas)
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{
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uint8_t s[7];
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#if defined(SECU_DEBUG)
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int i;
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#endif
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/* FC */
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s[0] = FC_ALG_KEY_DER;
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/* P0 = algorithm type distinguisher */
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s[1] = (uint8_t)(nas_alg_type & 0xFF);
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/* L0 = length(P0) = 1 */
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s[2] = 0x00;
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s[3] = 0x01;
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/* P1 */
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s[4] = nas_enc_alg_id;
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/* L1 = length(P1) = 1 */
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s[5] = 0x00;
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s[6] = 0x01;
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#if defined(SECU_DEBUG)
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for (i = 0; i < 7; i ++) {
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printf("0x%02x ", s[i]);
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}
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printf("\n");
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#endif
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kdf(s, 7, kasme, 32, knas, 32);
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return 0;
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}
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