45 lines
1.4 KiB
C
45 lines
1.4 KiB
C
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/* SPDX-License-Identifier: GPL-3.0-or-later
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* Copyright © 2019-2021 The TokTok team.
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*/
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#include "timed_auth.h"
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#include <string.h>
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#include "ccompat.h"
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non_null(1,6) nullable(4)
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static void create_timed_auth_to_hash(const Mono_Time *mono_time, uint16_t timeout, bool previous, const uint8_t *data,
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uint16_t length, uint8_t *to_hash)
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{
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const uint64_t t = (mono_time_get(mono_time) / timeout) - (previous ? 1 : 0);
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memcpy(to_hash, &t, sizeof(t));
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if (data != nullptr) {
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memcpy(to_hash + sizeof(t), data, length);
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}
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}
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void generate_timed_auth(const Mono_Time *mono_time, uint16_t timeout, const uint8_t *key,
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const uint8_t *data, uint16_t length, uint8_t *timed_auth)
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{
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VLA(uint8_t, to_hash, sizeof(uint64_t) + length);
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create_timed_auth_to_hash(mono_time, timeout, false, data, length, to_hash);
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crypto_hmac(timed_auth, key, to_hash, SIZEOF_VLA(to_hash));
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}
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bool check_timed_auth(const Mono_Time *mono_time, uint16_t timeout, const uint8_t *key, const uint8_t *data,
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uint16_t length, const uint8_t *timed_auth)
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{
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VLA(uint8_t, to_hash, sizeof(uint64_t) + length);
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for (uint8_t i = 0; i < 2; ++i) {
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create_timed_auth_to_hash(mono_time, timeout, i != 0, data, length, to_hash);
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if (crypto_hmac_verify(timed_auth, key, to_hash, SIZEOF_VLA(to_hash))) {
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return true;
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}
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}
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return false;
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}
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