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a479ee30c9
As this mode uses the public keys attached to the existing app's signatures to verify the next app, checking that a signature block is found on boot prevents the possibility of deploying a non-updatable device from the factory.
277 lines
11 KiB
C
277 lines
11 KiB
C
// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
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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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// 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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#pragma once
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#include <stdbool.h>
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#include <esp_err.h>
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#include "soc/efuse_periph.h"
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#include "esp_image_format.h"
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#include "esp_rom_efuse.h"
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#include "sdkconfig.h"
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#include "esp_rom_crc.h"
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#if CONFIG_IDF_TARGET_ESP32
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#include "esp32/rom/efuse.h"
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#include "esp32/rom/secure_boot.h"
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#elif CONFIG_IDF_TARGET_ESP32S2
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#include "esp32s2/rom/efuse.h"
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#include "esp32s2/rom/secure_boot.h"
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#elif CONFIG_IDF_TARGET_ESP32C3
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#include "esp32c3/rom/efuse.h"
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#include "esp32c3/rom/secure_boot.h"
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#elif CONFIG_IDF_TARGET_ESP32S3
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#include "esp32s3/rom/efuse.h"
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#include "esp32s3/rom/secure_boot.h"
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#endif
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#ifdef CONFIG_SECURE_BOOT_V1_ENABLED
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#if !defined(CONFIG_SECURE_SIGNED_ON_BOOT) || !defined(CONFIG_SECURE_SIGNED_ON_UPDATE) || !defined(CONFIG_SECURE_SIGNED_APPS)
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#error "internal sdkconfig error, secure boot should always enable all signature options"
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#endif
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#endif
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* Support functions for secure boot features.
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Can be compiled as part of app or bootloader code.
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*/
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#define ESP_SECURE_BOOT_DIGEST_LEN 32
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/** @brief Is secure boot currently enabled in hardware?
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*
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* This means that the ROM bootloader code will only boot
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* a verified secure bootloader from now on.
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*
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* @return true if secure boot is enabled.
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*/
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static inline bool esp_secure_boot_enabled(void)
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{
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#if CONFIG_IDF_TARGET_ESP32
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#ifdef CONFIG_SECURE_BOOT_V1_ENABLED
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return REG_READ(EFUSE_BLK0_RDATA6_REG) & EFUSE_RD_ABS_DONE_0;
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#elif CONFIG_SECURE_BOOT_V2_ENABLED
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return ets_use_secure_boot_v2();
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#endif
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#else
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return esp_rom_efuse_is_secure_boot_enabled();
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#endif
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return false; /* Secure Boot not enabled in menuconfig */
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}
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/** @brief Generate secure digest from bootloader image
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*
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* @important This function is intended to be called from bootloader code only.
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*
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* This function is only used in the context of the Secure Boot V1 scheme.
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*
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* If secure boot is not yet enabled for bootloader, this will:
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* 1) generate the secure boot key and burn it on EFUSE
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* (without enabling R/W protection)
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* 2) generate the digest from bootloader and save it
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* to flash address 0x0
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*
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* If first boot gets interrupted after calling this function
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* but before esp_secure_boot_permanently_enable() is called, then
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* the key burned on EFUSE will not be regenerated, unless manually
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* done using espefuse.py tool
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*
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* @return ESP_OK if secure boot digest is generated
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* successfully or found to be already present
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*/
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esp_err_t esp_secure_boot_generate_digest(void);
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/** @brief Enable secure boot V1 if it is not already enabled.
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*
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* @important If this function succeeds, secure boot V1 is permanently
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* enabled on the chip via efuse.
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*
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* @important This function is intended to be called from bootloader code only.
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*
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* @important In case of Secure Boot V1, this will enable r/w protection
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* of secure boot key on EFUSE, therefore it is to be ensured that
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* esp_secure_boot_generate_digest() is called before this .If secure boot is not
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* yet enabled for bootloader, this will
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* 1) enable R/W protection of secure boot key on EFUSE
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* 2) enable secure boot by blowing the EFUSE_RD_ABS_DONE_0 efuse.
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*
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* This function does not verify secure boot of the bootloader (the
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* ROM bootloader does this.)
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*
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* Will fail if efuses have been part-burned in a way that indicates
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* secure boot should not or could not be correctly enabled.
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*
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* @return ESP_ERR_INVALID_STATE if efuse state doesn't allow
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* secure boot to be enabled cleanly. ESP_OK if secure boot
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* is enabled on this chip from now on.
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*/
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esp_err_t esp_secure_boot_permanently_enable(void);
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/** @brief Enables secure boot V2 if it is not already enabled.
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*
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* @important If this function succeeds, secure boot V2 is permanently
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* enabled on the chip via efuse.
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*
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* @important This function is intended to be called from bootloader code only.
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*
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* @important In case of Secure Boot V2, this will enable write protection
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* of secure boot key on EFUSE in BLK2. .If secure boot is not
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* yet enabled for bootloader, this will
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* 1) enable W protection of secure boot key on EFUSE
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* 2) enable secure boot by blowing the EFUSE_RD_ABS_DONE_1 efuse.
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*
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* This function does not verify secure boot of the bootloader (the
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* ROM bootloader does this.)
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*
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* @param image_data Image metadata of the application to be loaded.
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*
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* Will fail if efuses have been part-burned in a way that indicates
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* secure boot should not or could not be correctly enabled.
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*
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* @return ESP_ERR_INVALID_STATE if efuse state doesn't allow
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* secure boot to be enabled cleanly. ESP_OK if secure boot
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* is enabled on this chip from now on.
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*/
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esp_err_t esp_secure_boot_v2_permanently_enable(const esp_image_metadata_t *image_data);
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/** @brief Verify the secure boot signature appended to some binary data in flash.
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*
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* For ECDSA Scheme (Secure Boot V1) - deterministic ECDSA w/ SHA256 image
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* For RSA Scheme (Secure Boot V2) - RSA-PSS Verification of the SHA-256 image
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*
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* Public key is compiled into the calling program in the ECDSA Scheme.
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* See the apt docs/security/secure-boot-v1.rst or docs/security/secure-boot-v2.rst for details.
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*
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* @param src_addr Starting offset of the data in flash.
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* @param length Length of data in bytes. Signature is appended -after- length bytes.
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*
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* If flash encryption is enabled, the image will be transparently decrypted while being verified.
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*
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* @note This function doesn't have any fault injection resistance so should not be called
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* during a secure boot itself (but can be called when verifying an update, etc.)
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*
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* @return ESP_OK if signature is valid, ESP_ERR_INVALID_STATE if
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* signature fails, ESP_FAIL for other failures (ie can't read flash).
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*/
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esp_err_t esp_secure_boot_verify_signature(uint32_t src_addr, uint32_t length);
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/** @brief Secure boot verification block, on-flash data format. */
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typedef struct {
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uint32_t version;
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uint8_t signature[64];
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} esp_secure_boot_sig_block_t;
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/** @brief Verify the ECDSA secure boot signature block for Secure Boot V1.
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*
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* Calculates Deterministic ECDSA w/ SHA256 based on the SHA256 hash of the image. ECDSA signature
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* verification must be enabled in project configuration to use this function.
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*
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* Similar to esp_secure_boot_verify_signature(), but can be used when the digest is precalculated.
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* @param sig_block Pointer to ECDSA signature block data
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* @param image_digest Pointer to 32 byte buffer holding SHA-256 hash.
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* @param verified_digest Pointer to 32 byte buffer that will receive verified digest if verification completes. (Used during bootloader implementation only, result is invalid otherwise.)
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*
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*/
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esp_err_t esp_secure_boot_verify_ecdsa_signature_block(const esp_secure_boot_sig_block_t *sig_block, const uint8_t *image_digest, uint8_t *verified_digest);
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#if !CONFIG_IDF_TARGET_ESP32 || CONFIG_ESP32_REV_MIN_3
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/**
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* @brief Structure to hold public key digests calculated from the signature blocks of a single image.
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*
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* Each image can have one or more signature blocks (up to SECURE_BOOT_NUM_BLOCKS). Each signature block includes a public key.
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*/
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typedef struct {
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uint8_t key_digests[SECURE_BOOT_NUM_BLOCKS][ESP_SECURE_BOOT_DIGEST_LEN]; /* SHA of the public key components in the signature block */
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unsigned num_digests; /* Number of valid digests, starting at index 0 */
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} esp_image_sig_public_key_digests_t;
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/** @brief Verify the RSA secure boot signature block for Secure Boot V2.
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*
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* Performs RSA-PSS Verification of the SHA-256 image based on the public key
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* in the signature block, compared against the public key digest stored in efuse.
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*
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* Similar to esp_secure_boot_verify_signature(), but can be used when the digest is precalculated.
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* @param sig_block Pointer to RSA signature block data
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* @param image_digest Pointer to 32 byte buffer holding SHA-256 hash.
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* @param verified_digest Pointer to 32 byte buffer that will receive verified digest if verification completes. (Used during bootloader implementation only, result is invalid otherwise.)
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*
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*/
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esp_err_t esp_secure_boot_verify_rsa_signature_block(const ets_secure_boot_signature_t *sig_block, const uint8_t *image_digest, uint8_t *verified_digest);
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#endif // !CONFIG_IDF_TARGET_ESP32 || CONFIG_ESP32_REV_MIN_3
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/** @brief Legacy ECDSA verification function
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*
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* @note Deprecated, call either esp_secure_boot_verify_ecdsa_signature_block() or esp_secure_boot_verify_rsa_signature_block() instead.
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*
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* @param sig_block Pointer to ECDSA signature block data
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* @param image_digest Pointer to 32 byte buffer holding SHA-256 hash.
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*/
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esp_err_t esp_secure_boot_verify_signature_block(const esp_secure_boot_sig_block_t *sig_block, const uint8_t *image_digest)
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__attribute__((deprecated("use esp_secure_boot_verify_ecdsa_signature_block instead")));
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#define FLASH_OFFS_SECURE_BOOT_IV_DIGEST 0
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/** @brief Secure boot IV+digest header */
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typedef struct {
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uint8_t iv[128];
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uint8_t digest[64];
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} esp_secure_boot_iv_digest_t;
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/** @brief Check the secure boot V2 during startup
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*
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* @note This function is called automatically during app startup,
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* it doesn't need to be called from the app.
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*
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* Verifies the secure boot config during startup:
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*
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* - Correct any insecure secure boot settings
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*/
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void esp_secure_boot_init_checks(void);
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#if !BOOTLOADER_BUILD && CONFIG_SECURE_SIGNED_APPS_RSA_SCHEME
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/** @brief Scan the current running app for signature blocks
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*
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* @note This function doesn't verify that the signatures are valid or the
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* corresponding public keys are trusted, it only reads the number of signature
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* blocks present and optionally calculates the digests of the public keys
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* provided in the signature blocks.
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*
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* @param digest_public_keys If true, the key_digests fields in the
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* public_key_digests structure will be filled with the digests of the public
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* key provided in each signature block. Note that if Secure Boot V2 is enabled,
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* each public key will only be trusted if the same digest is also present in
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* eFuse (but this is not checked by this function).
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*
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* @param public_key_digests[out] Structure is initialized with the num_digests
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* field set to the number of signatures found. If digest_public_keys is set,
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* the public key digests are also calculated and stored here.
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*
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* @return
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* - ESP_OK - At least one signature was found
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* - ESP_ERR_NOT_FOUND - No signatures were found, num_digests value will be zero
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* - ESP_FAIL - An error occured trying to read the signature blocks from flash
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*/
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esp_err_t esp_secure_boot_get_signature_blocks_for_running_app(bool digest_public_keys, esp_image_sig_public_key_digests_t *public_key_digests);
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#endif // !BOOTLOADER_BUILD && CONFIG_SECURE_SIGNED_APPS_RSA_SCHEME
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#ifdef __cplusplus
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}
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#endif
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