| /*! \file auth_xor.c |
| * GSM XOR-2G algorithm as specified in Annex 4 (A.4.1.2) of 3GPP TS 51.010-1. |
| * This is implemented by typical GSM MS tester */ |
| |
| /* |
| * (C) 2023 by Harald Welte <laforge@gnumonks.org> |
| * |
| * All Rights Reserved |
| * |
| * Author: Daniel Willmann <dwillmann@sysmocom.de> |
| * |
| * All Rights Reserved |
| * |
| * 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 <string.h> |
| #include <stdint.h> |
| #include <errno.h> |
| |
| #include <osmocom/crypt/auth.h> |
| |
| /*! \addtogroup auth |
| * @{ |
| */ |
| |
| static void xor(uint8_t *out, const uint8_t *a, const uint8_t *b, size_t len) |
| { |
| size_t i; |
| |
| for (i = 0; i < len; i++) |
| out[i] = a[i] ^ b[i]; |
| } |
| |
| /* GSM XOR-2G algorithm as specified in Annex 4 (A.4.1.2) of 3GPP TS 51.010-1. */ |
| static int xor2g_gen_vec(struct osmo_auth_vector *vec, |
| struct osmo_sub_auth_data2 *aud, |
| const uint8_t *_rand) |
| { |
| uint8_t res1[16]; |
| |
| OSMO_ASSERT(aud->algo == OSMO_AUTH_ALG_XOR_2G); |
| |
| if (aud->type != OSMO_AUTH_TYPE_GSM) |
| return -ENOTSUP; |
| |
| /* Step 1: XOR to the challenge RAND, a predefined number Ki, having the same bit length (128 bits) as |
| * RAND. */ |
| xor(res1, aud->u.gsm.ki, _rand, sizeof(res1)); |
| |
| /* Step 2: The most significant 32 bits of RES1 form SRES. */ |
| memcpy(vec->sres, res1, 4); |
| /* The next 64 bits of RES1 form Kc */ |
| memcpy(vec->kc, res1+4, 8); |
| |
| vec->auth_types = OSMO_AUTH_TYPE_GSM; |
| return 0; |
| } |
| |
| static struct osmo_auth_impl xor2g_alg = { |
| .algo = OSMO_AUTH_ALG_XOR_2G, |
| .name = "XOR-2G (libosmogsm built-in)", |
| .priority = 1000, |
| .gen_vec = &xor2g_gen_vec, |
| }; |
| |
| static __attribute__((constructor)) void on_dso_load_xor(void) |
| { |
| osmo_auth_register(&xor2g_alg); |
| } |
| |
| /*! @} */ |