Bluetooth: SMP: Add support for DHKey check
This implements LE SC f6 function use to calculate DH Key checks values. Calculated value is compared to value received from remote party and if match encryption is enabled. Change-Id: Iee66cbd19c0aa6d83edc6482dfb87943e4e45069 Signed-off-by: Szymon Janc <ext.szymon.janc@tieto.com>
This commit is contained in:
Szymon Janc
Anas Nashif
parent
176ea6af6b
commit
f0c84eb756
1 changed files with 182 additions and 7 deletions
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@ -1036,6 +1036,46 @@ static int smp_f5(const uint8_t *w, const uint8_t *n1, const uint8_t *n2,
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return 0;
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}
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static int smp_f6(const uint8_t *w, const uint8_t *n1, const uint8_t *n2,
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const uint8_t *r, const uint8_t *iocap, const bt_addr_le_t *a1,
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const bt_addr_le_t *a2, uint8_t *check)
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{
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uint8_t ws[16];
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uint8_t m[65];
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int err;
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BT_DBG("w %s\n", h(w, 16));
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BT_DBG("n1 %s n2 %s\n", h(n1, 16), h(n2, 16));
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BT_DBG("r %s io_cap\n", h(r, 16), h(iocap, 3));
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BT_DBG("a1 %s a2 %s\n", h(a1, 7), h(a2, 7));
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swap_buf(n1, m, 16);
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swap_buf(n2, m + 16, 16);
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swap_buf(r, m + 32, 16);
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swap_buf(iocap, m + 48, 3);
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m[51] = a1->type;
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memcpy(m + 52, a1->val, 6);
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swap_buf(a1->val, m + 52, 6);
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m[58] = a2->type;
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memcpy(m + 59, a2->val, 6);
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swap_buf(a2->val, m + 59, 6);
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swap_buf(w, ws, 16);
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err = bt_smp_aes_cmac(ws, m, sizeof(m), check);
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if (err) {
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return err;
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}
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BT_DBG("res %s\n", h(check, 16));
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swap_in_place(check, 16);
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return 0;
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}
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static uint8_t smp_send_pairing_confirm(struct bt_smp *smp)
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{
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struct bt_conn *conn = smp->chan.conn;
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@ -1286,7 +1326,6 @@ static uint8_t get_encryption_key_size(struct bt_smp *smp)
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return min(req->max_key_size, rsp->max_key_size);
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}
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#if defined(CONFIG_BLUETOOTH_CENTRAL)
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static uint8_t sc_smp_send_dhkey_check(struct bt_smp *smp, const uint8_t *e)
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{
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struct bt_smp_dhkey_check *req;
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@ -1307,12 +1346,16 @@ static uint8_t sc_smp_send_dhkey_check(struct bt_smp *smp, const uint8_t *e)
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return 0;
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}
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#endif
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static uint8_t smp_sc_calculate_ltk_mac_dhcheck(struct bt_smp *smp, uint8_t *e)
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{
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uint8_t r[16];
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BT_DBG("\n");
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/* TODO currently only NumComparison/JustWorks */
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memset(r, 0, sizeof(r));
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#if defined(CONFIG_BLUETOOTH_CENTRAL)
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if (smp->chan.conn->role == BT_HCI_ROLE_MASTER) {
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/* calculate LTK and mackey */
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@ -1322,8 +1365,14 @@ static uint8_t smp_sc_calculate_ltk_mac_dhcheck(struct bt_smp *smp, uint8_t *e)
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smp->tk)) {
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return BT_SMP_ERR_UNSPECIFIED;
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}
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/* TODO dhkey check */
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return BT_SMP_ERR_UNSPECIFIED;
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/* calculate local DHKey check */
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if (smp_f6(smp->mackey, smp->prnd, smp->rrnd, r, &smp->preq[1],
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&smp->chan.conn->le.init_addr,
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&smp->chan.conn->le.resp_addr, e)) {
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return BT_SMP_ERR_UNSPECIFIED;
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}
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return 0;
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}
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#endif /* CONFIG_BLUETOOTH_CENTRAL */
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@ -1336,9 +1385,14 @@ static uint8_t smp_sc_calculate_ltk_mac_dhcheck(struct bt_smp *smp, uint8_t *e)
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return BT_SMP_ERR_UNSPECIFIED;
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}
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/* TODO dhkey check */
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/* calculate local DHKey check */
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if (smp_f6(smp->mackey, smp->prnd, smp->rrnd, r, &smp->prsp[1],
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&smp->chan.conn->le.resp_addr,
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&smp->chan.conn->le.init_addr, e)) {
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return BT_SMP_ERR_UNSPECIFIED;
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}
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#endif /* CONFIG_BLUETOOTH_PERIPHERAL */
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return BT_SMP_ERR_UNSPECIFIED;
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return 0;
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}
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void bt_smp_dhkey_ready(const uint8_t *dhkey)
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@ -1384,10 +1438,32 @@ void bt_smp_dhkey_ready(const uint8_t *dhkey)
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#endif /* CONFIG_BLUETOOTH_CENTRAL */
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#if defined(CONFIG_BLUETOOTH_PERIPHERAL)
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if (atomic_test_bit(&smp->flags, SMP_FLAG_DHKEY_SEND)) {
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uint8_t e[16];
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uint8_t r[16], e[16], re[16];
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/* calculate mac, ltk and local dhcheck */
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smp_sc_calculate_ltk_mac_dhcheck(smp, e);
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/* TODO currently only NumComparison/JustWorks */
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memset(r, 0, sizeof(r));
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/* calculate remote DHKey check */
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if (smp_f6(smp->mackey, smp->prnd, smp->rrnd, r, &smp->preq[1],
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&smp->chan.conn->le.init_addr,
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&smp->chan.conn->le.resp_addr, re)) {
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send_err_rsp(smp->chan.conn, BT_SMP_ERR_UNSPECIFIED);
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return;
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}
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/* compare received E with calculated remote */
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if (memcmp(smp->e, re, 16)) {
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send_err_rsp(smp->chan.conn,
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BT_SMP_ERR_DHKEY_CHECK_FAILED);
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return;
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}
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/* send local e */
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sc_smp_send_dhkey_check(smp, e);
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atomic_set_bit(&smp->flags, SMP_FLAG_ENC_PENDING);
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}
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#endif /* CONFIG_BLUETOOTH_PERIPHERAL */
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}
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@ -1975,6 +2051,104 @@ static uint8_t smp_public_key(struct bt_smp *smp, struct net_buf *buf)
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return 0;
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}
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static uint8_t smp_dhkey_check(struct bt_smp *smp, struct net_buf *buf)
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{
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struct bt_smp_dhkey_check *req = (void *)buf->data;
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struct bt_keys *keys;
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uint8_t e[16], r[16];
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BT_DBG("\n");
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keys = bt_keys_get_addr(&smp->chan.conn->le.dst);
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if (!keys) {
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return BT_SMP_ERR_UNSPECIFIED;
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}
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/* TODO currently only NumComparison/JustWorks */
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memset(r, 0, sizeof(r));
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#if defined(CONFIG_BLUETOOTH_CENTRAL)
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if (smp->chan.conn->role == BT_HCI_ROLE_MASTER) {
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/* calculate remote DHKey check for comparison */
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if (smp_f6(smp->mackey, smp->rrnd, smp->prnd, r, &smp->prsp[1],
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&smp->chan.conn->le.resp_addr,
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&smp->chan.conn->le.init_addr, e)) {
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return BT_SMP_ERR_UNSPECIFIED;
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}
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if (memcmp(e, req->e, 16)) {
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return BT_SMP_ERR_DHKEY_CHECK_FAILED;
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}
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/*
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* store key type deducted from pairing method used
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* it is important to store it since type is used to determine
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* security level upon encryption
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*/
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keys->type = get_keys_type(smp->method);
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keys->enc_size = get_encryption_key_size(smp);
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if (bt_conn_le_start_encryption(smp->chan.conn, 0, 0, smp->tk,
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keys->enc_size) < 0) {
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return BT_SMP_ERR_UNSPECIFIED;
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}
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atomic_set_bit(&smp->flags, SMP_FLAG_ENC_PENDING);
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return 0;
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}
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#endif /* CONFIG_BLUETOOTH_CENTRAL */
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#if defined(CONFIG_BLUETOOTH_PERIPHERAL)
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if (smp->chan.conn->role == BT_HCI_ROLE_SLAVE) {
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uint8_t re[16];
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/* wait for DHKey being generated */
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if (atomic_test_bit(&smp->flags, SMP_FLAG_DHKEY_PENDING)) {
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atomic_set_bit(&smp->flags, SMP_FLAG_DHKEY_SEND);
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memcpy(smp->e, req->e, sizeof(smp->e));
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return 0;
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}
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/* calculate mac, ltk and local dhcheck */
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smp_sc_calculate_ltk_mac_dhcheck(smp, e);
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/* calculate remote DHKey check */
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if (smp_f6(smp->mackey, smp->rrnd, smp->prnd, r, &smp->preq[1],
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&smp->chan.conn->le.init_addr,
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&smp->chan.conn->le.resp_addr, re)) {
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return BT_SMP_ERR_UNSPECIFIED;
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}
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/* compare received E with calculated remote */
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if (memcmp(req->e, re, 16)) {
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return BT_SMP_ERR_DHKEY_CHECK_FAILED;
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}
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/*
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* store key type deducted from pairing method used
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* it is important to store it since type is used to determine
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* security level upon encryption
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*/
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keys->type = get_keys_type(smp->method);
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keys->enc_size = get_encryption_key_size(smp);
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/*
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* this is safe since LE SC is mutually exclusive with legacy
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* pairing
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*/
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bt_keys_add_type(keys, BT_KEYS_LTK_P256);
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memcpy(keys->ltk.val, smp->tk, sizeof(keys->ltk.val));
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keys->slave_ltk.rand = 0;
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keys->slave_ltk.ediv = 0;
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/* send local e */
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sc_smp_send_dhkey_check(smp, e);
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atomic_set_bit(&smp->flags, SMP_FLAG_ENC_PENDING);
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}
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#endif /* CONFIG_BLUETOOTH_PERIPHERAL */
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return 0;
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}
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static const struct {
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uint8_t (*func)(struct bt_smp *smp, struct net_buf *buf);
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uint8_t expect_len;
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@ -1992,6 +2166,7 @@ static const struct {
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{ smp_signing_info, sizeof(struct bt_smp_signing_info) },
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{ smp_security_request, sizeof(struct bt_smp_security_request) },
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{ smp_public_key, sizeof(struct bt_smp_public_key) },
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{ smp_dhkey_check, sizeof(struct bt_smp_dhkey_check) },
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};
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static void bt_smp_recv(struct bt_l2cap_chan *chan, struct net_buf *buf)
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