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* @file rpa.c
* Resolvable Private Address Generation and Resolution
*/
/*
* Copyright (c) 2017 Nordic Semiconductor ASA
* Copyright (c) 2015-2016 Intel Corporation
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <zephyr/kernel.h>
#include <stddef.h>
#include <errno.h>
#include <string.h>
#define BT_DBG_ENABLED IS_ENABLED(CONFIG_BT_DEBUG_RPA)
#define LOG_MODULE_NAME bt_rpa
#include "common/log.h"
#include <zephyr/bluetooth/crypto.h>
#if defined(CONFIG_BT_CTLR) && defined(CONFIG_BT_HOST_CRYPTO)
#include "../controller/util/util.h"
#include "../controller/hal/ecb.h"
#endif /* defined(CONFIG_BT_CTLR) && defined(CONFIG_BT_HOST_CRYPTO) */
#if defined(CONFIG_BT_PRIVACY) || defined(CONFIG_BT_CTLR_PRIVACY)
static int internal_rand(void *buf, size_t len)
{
/* Force using controller rand function. */
#if defined(CONFIG_BT_CTLR) && defined(CONFIG_BT_HOST_CRYPTO)
return lll_csrand_get(buf, len);
#else
return bt_rand(buf, len);
#endif
}
#endif /* defined(CONFIG_BT_PRIVACY) || defined(CONFIG_BT_CTLR_PRIVACY) */
static int internal_encrypt_le(const uint8_t key[16], const uint8_t plaintext[16],
uint8_t enc_data[16])
{
/* Force using controller encrypt function if supported. */
#if defined(CONFIG_BT_CTLR) && defined(CONFIG_BT_HOST_CRYPTO) && \
defined(CONFIG_BT_CTLR_LE_ENC)
ecb_encrypt(key, plaintext, enc_data, NULL);
return 0;
#else
return bt_encrypt_le(key, plaintext, enc_data);
#endif
}
static int ah(const uint8_t irk[16], const uint8_t r[3], uint8_t out[3])
{
uint8_t res[16];
int err;
BT_DBG("irk %s", bt_hex(irk, 16));
BT_DBG("r %s", bt_hex(r, 3));
/* r' = padding || r */
memcpy(res, r, 3);
(void)memset(res + 3, 0, 13);
err = internal_encrypt_le(irk, res, res);
if (err) {
return err;
}
/* The output of the random address function ah is:
* ah(h, r) = e(k, r') mod 2^24
* The output of the security function e is then truncated to 24 bits
* by taking the least significant 24 bits of the output of e as the
* result of ah.
*/
memcpy(out, res, 3);
return 0;
}
#if defined(CONFIG_BT_SMP) || defined(CONFIG_BT_CTLR_PRIVACY)
bool bt_rpa_irk_matches(const uint8_t irk[16], const bt_addr_t *addr)
{
uint8_t hash[3];
int err;
BT_DBG("IRK %s bdaddr %s", bt_hex(irk, 16), bt_addr_str(addr));
err = ah(irk, addr->val + 3, hash);
if (err) {
return false;
}
return !memcmp(addr->val, hash, 3);
}
#endif
#if defined(CONFIG_BT_PRIVACY) || defined(CONFIG_BT_CTLR_PRIVACY)
int bt_rpa_create(const uint8_t irk[16], bt_addr_t *rpa)
{
int err;
err = internal_rand(rpa->val + 3, 3);
if (err) {
return err;
}
BT_ADDR_SET_RPA(rpa);
err = ah(irk, rpa->val + 3, rpa->val);
if (err) {
return err;
}
BT_DBG("Created RPA %s", bt_addr_str((bt_addr_t *)rpa->val));
return 0;
}
#else
int bt_rpa_create(const uint8_t irk[16], bt_addr_t *rpa)
{
return -ENOTSUP;
}
#endif /* CONFIG_BT_PRIVACY */
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