mirror of https://gerrit.osmocom.org/libosmocore
82 lines
2.0 KiB
C
82 lines
2.0 KiB
C
/*! \file auth_xor.c
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* GSM XOR-2G algorithm as specified in Annex 4 (A.4.1.2) of 3GPP TS 51.010-1.
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* This is implemented by typical GSM MS tester */
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/*
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* (C) 2023 by Harald Welte <laforge@gnumonks.org>
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*
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* All Rights Reserved
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*
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* Author: Daniel Willmann <dwillmann@sysmocom.de>
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*
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* All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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#include <string.h>
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#include <stdint.h>
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#include <errno.h>
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#include <osmocom/crypt/auth.h>
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/*! \addtogroup auth
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* @{
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*/
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static void xor(uint8_t *out, const uint8_t *a, const uint8_t *b, size_t len)
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{
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size_t i;
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for (i = 0; i < len; i++)
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out[i] = a[i] ^ b[i];
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}
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/* GSM XOR-2G algorithm as specified in Annex 4 (A.4.1.2) of 3GPP TS 51.010-1. */
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static int xor2g_gen_vec(struct osmo_auth_vector *vec,
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struct osmo_sub_auth_data2 *aud,
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const uint8_t *_rand)
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{
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uint8_t res1[16];
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OSMO_ASSERT(aud->algo == OSMO_AUTH_ALG_XOR_2G);
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if (aud->type != OSMO_AUTH_TYPE_GSM)
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return -ENOTSUP;
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/* Step 1: XOR to the challenge RAND, a predefined number Ki, having the same bit length (128 bits) as
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* RAND. */
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xor(res1, aud->u.gsm.ki, _rand, sizeof(res1));
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/* Step 2: The most significant 32 bits of RES1 form SRES. */
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memcpy(vec->sres, res1, 4);
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/* The next 64 bits of RES1 form Kc */
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memcpy(vec->kc, res1+4, 8);
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vec->auth_types = OSMO_AUTH_TYPE_GSM;
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return 0;
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}
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static struct osmo_auth_impl xor2g_alg = {
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.algo = OSMO_AUTH_ALG_XOR_2G,
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.name = "XOR-2G (libosmogsm built-in)",
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.priority = 1000,
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.gen_vec = &xor2g_gen_vec,
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};
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static __attribute__((constructor)) void on_dso_load_xor(void)
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{
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osmo_auth_register(&xor2g_alg);
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}
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/*! @} */
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