mirror of
https://github.com/trezor/trezor-firmware.git
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116 lines
3.2 KiB
C
116 lines
3.2 KiB
C
/**
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* Copyright (c) SatoshiLabs
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included
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* in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES
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* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include <assert.h>
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#include <stdatomic.h>
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#include <stdbool.h>
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#include "memzero.h"
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#include "rand.h"
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#include "zkp_context.h"
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#include "vendor/secp256k1-zkp/include/secp256k1.h"
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static uint8_t context_buffer[SECP256K1_CONTEXT_SIZE];
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static secp256k1_context *context;
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static volatile atomic_flag locked;
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// returns 0 on success
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int secp256k1_context_writable_randomize(secp256k1_context *context_writable) {
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uint8_t seed[32] = {0};
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random_buffer(seed, sizeof(seed));
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int returned = secp256k1_context_randomize(context_writable, seed);
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memzero(seed, sizeof(seed));
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if (returned != 1) {
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return 1;
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}
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return 0;
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}
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bool zkp_context_is_initialized(void) { return context != NULL; }
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// returns 0 on success
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int zkp_context_init(void) {
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assert(context == NULL);
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const unsigned int context_flags =
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SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_VERIFY;
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const size_t context_size =
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secp256k1_context_preallocated_size(context_flags);
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// Assert the context is as small as possible
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assert(context_size == SECP256K1_CONTEXT_SIZE);
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if (context_size == 0 || context_size > SECP256K1_CONTEXT_SIZE) {
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return 1;
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}
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context =
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secp256k1_context_preallocated_create(context_buffer, context_flags);
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if (context == NULL) {
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return 1;
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}
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if (secp256k1_context_writable_randomize(context) != 0) {
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zkp_context_destroy();
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return 1;
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}
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atomic_flag_clear(&locked);
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return 0;
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}
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void zkp_context_destroy(void) {
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assert(context != NULL);
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secp256k1_context_preallocated_destroy(context);
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memzero(context_buffer, sizeof(context_buffer));
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atomic_flag_clear(&locked);
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context = NULL;
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}
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const secp256k1_context *zkp_context_get_read_only(void) {
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assert(context != NULL);
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return context;
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}
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// returns NULL if context cannot be acquired
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secp256k1_context *zkp_context_acquire_writable(void) {
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assert(context != NULL);
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// We don't expect the context to be used by multiple threads
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if (atomic_flag_test_and_set(&locked)) {
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return NULL;
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}
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return context;
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}
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void zkp_context_release_writable(void) {
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assert(context != NULL);
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atomic_flag_clear(&locked);
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}
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