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Diffstat (limited to 'src/gsm/kdf.c')
| -rw-r--r-- | src/gsm/kdf.c | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/src/gsm/kdf.c b/src/gsm/kdf.c new file mode 100644 index 00000000..4113aada --- /dev/null +++ b/src/gsm/kdf.c @@ -0,0 +1,163 @@ +/* + * (C) 2021 by sysmocom s.f.m.c. GmbH + * + * Author: Eric Wild <ewild@sysmocom.de> + * + * All Rights Reserved + * + * SPDX-License-Identifier: GPL-2.0+ + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + */ + +#include <stdint.h> +#include <string.h> + +#include "config.h" +#if (USE_GNUTLS) +#include <gnutls/gnutls.h> +#include <gnutls/crypto.h> +#define HMAC_FUNC(k,lk,s,sl,out) gnutls_hmac_fast(GNUTLS_MAC_SHA256,k,lk,s,sl,out) +#else +#include <osmocom/crypt/kdf.h> +#define HMAC_FUNC(k,lk,s,sl,out) hmac_sha256(k,lk,s,sl,out) +#endif + +#include <osmocom/core/bit32gen.h> +#include <osmocom/crypt/kdf.h> + +#include "kdf/common.h" +#include "kdf/sha256.h" + + +#if (USE_GNUTLS) +/* gnutls < 3.3.0 requires global init. + * gnutls >= 3.3.0 does it automatic. + * It doesn't hurt calling it twice, + * as long it's not done at the same time (threads). + */ +__attribute__((constructor)) +static void on_dso_load_gnutls(void) +{ + if (!gnutls_check_version("3.3.0")) + gnutls_global_init(); +} + +__attribute__((destructor)) +static void on_dso_unload_gnutls(void) +{ + if (!gnutls_check_version("3.3.0")) + gnutls_global_deinit(); +} +#endif + +/* + * This file uses the generic key derivation function defined in 3GPP TS 33.220 Annex B + * + * The S parameter always consists of concatenated values FC | P0 | L0 | Pi | Li | ... + * with Pi = Parameter number i and Li = Length of Pi (two octets) + * + * FC is either a single octet or two octets 0xff | FC + * FC values ranges depend on the specification parts that use the KDF, + * they are defined in 3GPP TS 33.220 Annex B.2.2 + * + */ + +/*! \addtogroup kdf + * @{ + * key derivation functions + * + * \file kdf.c */ + +/* 3GPP TS 33.102 B.5 */ +void osmo_kdf_kc128(const uint8_t* ck, const uint8_t* ik, uint8_t* kc128) { + uint8_t k[16*2]; + uint8_t s[1]; + uint8_t out_tmp256[32]; + memcpy (&k[0], ck, 16); + memcpy (&k[16], ik, 16); + + s[0] = 0x32; // yeah, really just one FC byte.. + + HMAC_FUNC(k, 32, s, 1, out_tmp256); + memcpy(kc128, out_tmp256, 16); +} + +/* 3GPP TS 33.401 A.2 */ +void osmo_kdf_kasme(const uint8_t *ck, const uint8_t *ik, const uint8_t* plmn_id, + const uint8_t *sqn, const uint8_t *ak, uint8_t *kasme) +{ + uint8_t s[14]; + uint8_t k[16*2]; + int i; + + memcpy(&k[0], ck, 16); + memcpy(&k[16], ik, 16); + + s[0] = 0x10; + memcpy(&s[1], plmn_id, 3); + s[4] = 0x00; + s[5] = 0x03; + + for (i = 0; i < 6; i++) + s[6+i] = sqn[i] ^ ak[i]; + s[12] = 0x00; + s[13] = 0x06; + + HMAC_FUNC(k, 32, s, 14, kasme); +} + +/* 3GPP TS 33.401 A.3 */ +void osmo_kdf_enb(const uint8_t *kasme, uint32_t ul_count, uint8_t *kenb) +{ + uint8_t s[7]; + + s[0] = 0x11; + osmo_store32be(ul_count, &s[1]); + s[5] = 0x00; + s[6] = 0x04; + + HMAC_FUNC(kasme, 32, s, 7, kenb); +} + +/* 3GPP TS 33.401 A.4 */ +void osmo_kdf_nh(const uint8_t *kasme, const uint8_t *sync_input, uint8_t *nh) +{ + uint8_t s[35]; + + s[0] = 0x12; + memcpy(s+1, sync_input, 32); + s[33] = 0x00; + s[34] = 0x20; + + HMAC_FUNC(kasme, 32, s, 35, nh); +} + +/* 3GPP TS 33.401 A.7 */ +void osmo_kdf_nas(uint8_t algo_type, uint8_t algo_id, const uint8_t *kasme, uint8_t *knas) +{ + uint8_t s[7]; + uint8_t out[32]; + + s[0] = 0x15; + s[1] = algo_type; + s[2] = 0x00; + s[3] = 0x01; + s[4] = algo_id; + s[5] = 0x00; + s[6] = 0x01; + + HMAC_FUNC(kasme, 32, s, 7, out); + memcpy(knas, out+16, 16); +} + +/*! @} */ |