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70 lines
2.3 KiB
C
70 lines
2.3 KiB
C
/*
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* Copyright 2024 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "drivers/rng.h"
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#include "services/common/bluetooth/ble_root_keys.h"
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#include "services/common/bluetooth/bluetooth_persistent_storage.h"
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#include "system/hexdump.h"
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#include "system/logging.h"
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#include <bluetooth/sm_types.h>
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static void prv_generate_root_keys(SM128BitKey *keys_out) {
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uint8_t *rand_buffer = (uint8_t *)keys_out;
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int tries_left = 20;
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// rng_rand generates only 4 bytes of random data at a time. Loop to fill up the whole array:
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for (uint32_t i = 0; i < ((sizeof(SM128BitKey) * SMRootKeyTypeNum) / sizeof(uint32_t)); ++i) {
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while (tries_left) {
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const bool success = rng_rand((uint32_t *) &rand_buffer[i * sizeof(uint32_t)]);
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if (success) {
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break;
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}
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--tries_left;
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}
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}
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if (tries_left == 0) {
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PBL_LOG(LOG_LEVEL_WARNING, "rng_rand() failed too many times, falling back to rand()");
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// Fall back to rand():
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for (uint32_t i = 0; i < (sizeof(SM128BitKey) * SMRootKeyTypeNum); ++i) {
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rand_buffer[i] = rand();
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}
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}
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}
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void ble_root_keys_get_and_generate_if_needed(SM128BitKey *keys_out) {
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SM128BitKey *enc_key = &keys_out[SMRootKeyTypeEncryption];
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SM128BitKey *id_key = &keys_out[SMRootKeyTypeIdentity];
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bool is_existing = false;
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if (bt_persistent_storage_get_root_key(SMRootKeyTypeIdentity, id_key) &&
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bt_persistent_storage_get_root_key(SMRootKeyTypeEncryption, enc_key)) {
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is_existing = true;
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goto finally;
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}
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prv_generate_root_keys(keys_out);
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finally:
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#ifndef RELEASE
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PBL_LOG(LOG_LEVEL_INFO, "BLE Root Keys (existing=%u):", is_existing);
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PBL_HEXDUMP(LOG_LEVEL_INFO, (const uint8_t *)keys_out, 2 * sizeof(SM128BitKey));
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#endif
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if (!is_existing) {
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bt_persistent_storage_set_root_keys(keys_out);
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}
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}
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