kopia lustrzana https://github.com/espressif/esp-idf
181 wiersze
5.8 KiB
C
181 wiersze
5.8 KiB
C
/*
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* SPDX-FileCopyrightText: 2015-2021 Espressif Systems (Shanghai) CO LTD
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <string.h>
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#include "esp_private/periph_ctrl.h"
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#include "esp32c3/rom/hmac.h"
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#include "esp32c3/rom/ets_sys.h"
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#include "esp_efuse.h"
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#include "esp_efuse_table.h"
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#include "esp_hmac.h"
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#include "esp_log.h"
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#include "esp_crypto_lock.h"
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#include "soc/hwcrypto_reg.h"
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#include "hal/hmac_hal.h"
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#define SHA256_BLOCK_SZ 64
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#define SHA256_PAD_SZ 8
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static const char *TAG = "esp_hmac";
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/**
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* @brief Apply the HMAC padding without the embedded length.
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*
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* @note This function does not check the data length, it is the responsibility of the other functions in this
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* module to make sure that \c data_len is at most SHA256_BLOCK_SZ - 1 so the padding fits in.
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* Otherwise, this function has undefined behavior.
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* Note however, that for the actual HMAC implementation on ESP32C3, the length also needs to be applied at the end
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* of the block. This function alone deosn't do that.
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*/
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static void write_and_padd(uint8_t *block, const uint8_t *data, uint16_t data_len)
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{
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memcpy(block, data, data_len);
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// Apply a one bit, followed by zero bits (refer to the ESP32C3 TRM).
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block[data_len] = 0x80;
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bzero(block + data_len + 1, SHA256_BLOCK_SZ - data_len - 1);
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}
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esp_err_t esp_hmac_calculate(hmac_key_id_t key_id,
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const void *message,
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size_t message_len,
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uint8_t *hmac)
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{
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const uint8_t *message_bytes = (const uint8_t *)message;
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if (!message || !hmac) {
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return ESP_ERR_INVALID_ARG;
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}
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if (key_id >= HMAC_KEY_MAX) {
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return ESP_ERR_INVALID_ARG;
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}
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esp_crypto_hmac_lock_acquire();
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// We also enable SHA and DS here. SHA is used by HMAC, DS will otherwise hold SHA in reset state.
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periph_module_enable(PERIPH_HMAC_MODULE);
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periph_module_enable(PERIPH_SHA_MODULE);
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periph_module_enable(PERIPH_DS_MODULE);
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hmac_hal_start();
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uint32_t conf_error = hmac_hal_configure(HMAC_OUTPUT_USER, key_id);
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if (conf_error) {
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esp_crypto_hmac_lock_release();
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return ESP_FAIL;
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}
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if (message_len + 1 + SHA256_PAD_SZ <= SHA256_BLOCK_SZ) {
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// If message including padding is only one block...
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// Last message block, so apply SHA-256 padding rules in software
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uint8_t block[SHA256_BLOCK_SZ];
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uint64_t bit_len = __builtin_bswap64(message_len * 8 + 512);
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write_and_padd(block, message_bytes, message_len);
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// Final block: append the bit length in this block and signal padding to peripheral
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memcpy(block + SHA256_BLOCK_SZ - sizeof(bit_len),
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&bit_len, sizeof(bit_len));
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hmac_hal_write_one_block_512(block);
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} else {
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// If message including padding is needs more than one block
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// write all blocks without padding except the last one
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size_t remaining_blocks = message_len / SHA256_BLOCK_SZ;
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for (int i = 1; i < remaining_blocks; i++) {
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hmac_hal_write_block_512(message_bytes);
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message_bytes += SHA256_BLOCK_SZ;
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hmac_hal_next_block_normal();
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}
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// If message fits into one block but without padding, we must not write another block.
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if (remaining_blocks) {
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hmac_hal_write_block_512(message_bytes);
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message_bytes += SHA256_BLOCK_SZ;
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}
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size_t remaining = message_len % SHA256_BLOCK_SZ;
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// Last message block, so apply SHA-256 padding rules in software
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uint8_t block[SHA256_BLOCK_SZ];
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uint64_t bit_len = __builtin_bswap64(message_len * 8 + 512);
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// If the remaining message and appended padding doesn't fit into a single block, we have to write an
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// extra block with the rest of the message and potential padding first.
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if (remaining >= SHA256_BLOCK_SZ - SHA256_PAD_SZ) {
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write_and_padd(block, message_bytes, remaining);
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hmac_hal_next_block_normal();
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hmac_hal_write_block_512(block);
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bzero(block, SHA256_BLOCK_SZ);
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} else {
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write_and_padd(block, message_bytes, remaining);
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}
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memcpy(block + SHA256_BLOCK_SZ - sizeof(bit_len),
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&bit_len, sizeof(bit_len));
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hmac_hal_next_block_padding();
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hmac_hal_write_block_512(block);
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}
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// Read back result (bit swapped)
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hmac_hal_read_result_256(hmac);
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periph_module_disable(PERIPH_DS_MODULE);
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periph_module_disable(PERIPH_SHA_MODULE);
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periph_module_disable(PERIPH_HMAC_MODULE);
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esp_crypto_hmac_lock_release();
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return ESP_OK;
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}
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static ets_efuse_block_t convert_key_type(hmac_key_id_t key_id) {
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return ETS_EFUSE_BLOCK_KEY0 + (ets_efuse_block_t) key_id;
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}
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esp_err_t esp_hmac_jtag_enable(hmac_key_id_t key_id, const uint8_t *token)
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{
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int ets_status;
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esp_err_t err = ESP_OK;
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if ((!token) || (key_id >= HMAC_KEY_MAX))
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return ESP_ERR_INVALID_ARG;
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/* Check if JTAG is permanently disabled by HW Disable eFuse */
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if (esp_efuse_read_field_bit(ESP_EFUSE_DIS_PAD_JTAG)) {
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ESP_LOGE(TAG, "JTAG disabled permanently.");
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return ESP_FAIL;
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}
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esp_crypto_hmac_lock_acquire();
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ets_status = ets_jtag_enable_temporarily(token, convert_key_type(key_id));
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if (ets_status != ETS_OK) {
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// ets_jtag_enable_temporarily returns either ETS_OK or ETS_FAIL
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err = ESP_FAIL;
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ESP_LOGE(TAG, "JTAG re-enabling failed (%d)", err);
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}
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ESP_LOGD(TAG, "HMAC computation in downstream mode is completed.");
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ets_hmac_disable();
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esp_crypto_hmac_lock_release();
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return err;
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}
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esp_err_t esp_hmac_jtag_disable()
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{
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esp_crypto_hmac_lock_acquire();
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REG_SET_BIT(HMAC_SET_INVALIDATE_JTAG_REG, HMAC_INVALIDATE_JTAG);
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esp_crypto_hmac_lock_release();
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ESP_LOGD(TAG, "Invalidate JTAG result register. JTAG disabled.");
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return ESP_OK;
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}
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