17adb40ca8
Makes app image booting more reliable (256-bit rather than 8-bit verification.) Some measurements, time to boot a 655KB app.bin file and run to app_main() execution. (All for rev 1 silicon, ie no 340ms spurious WDT delay.) 80MHz QIO mode: before = 300ms after = 140ms 40MHz DIO mode: before = 712ms after = 577ms 40MHz DIO mode, secure boot enabled before = 1380ms after = 934ms (Secure boot involves two ECC signature verifications (partition table, app) that take approx 300ms each with 80MHz CPU.)
94 lines
3.2 KiB
C
94 lines
3.2 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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#include "sdkconfig.h"
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#include "bootloader_flash.h"
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#include "bootloader_sha.h"
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#include "esp_log.h"
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#include "esp_image_format.h"
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#include "esp_secure_boot.h"
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#include "uECC.h"
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#ifdef BOOTLOADER_BUILD
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#include "rom/sha.h"
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typedef SHA_CTX sha_context;
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#else
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#include "hwcrypto/sha.h"
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#endif
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static const char* TAG = "secure_boot";
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extern const uint8_t signature_verification_key_start[] asm("_binary_signature_verification_key_bin_start");
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extern const uint8_t signature_verification_key_end[] asm("_binary_signature_verification_key_bin_end");
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#define SIGNATURE_VERIFICATION_KEYLEN 64
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#define DIGEST_LEN 32
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esp_err_t esp_secure_boot_verify_signature(uint32_t src_addr, uint32_t length)
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{
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uint8_t digest[DIGEST_LEN];
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const uint8_t *data;
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const esp_secure_boot_sig_block_t *sigblock;
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ESP_LOGD(TAG, "verifying signature src_addr 0x%x length 0x%x", src_addr, length);
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data = bootloader_mmap(src_addr, length + sizeof(esp_secure_boot_sig_block_t));
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if(data == NULL) {
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ESP_LOGE(TAG, "bootloader_mmap(0x%x, 0x%x) failed", src_addr, length+sizeof(esp_secure_boot_sig_block_t));
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return ESP_FAIL;
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}
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// Calculate digest of main image
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#ifdef BOOTLOADER_BUILD
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bootloader_sha256_handle_t handle = bootloader_sha256_start();
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bootloader_sha256_data(handle, data, length);
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bootloader_sha256_finish(handle, digest);
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#else
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/* Use thread-safe esp-idf SHA function */
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esp_sha(SHA2_256, data, length, digest);
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#endif
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// Map the signature block and verify the signature
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sigblock = (const esp_secure_boot_sig_block_t *)(data + length);
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esp_err_t err = esp_secure_boot_verify_signature_block(sigblock, digest);
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bootloader_munmap(data);
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return err;
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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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{
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ptrdiff_t keylen;
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bool is_valid;
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keylen = signature_verification_key_end - signature_verification_key_start;
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if(keylen != SIGNATURE_VERIFICATION_KEYLEN) {
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ESP_LOGE(TAG, "Embedded public verification key has wrong length %d", keylen);
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return ESP_FAIL;
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}
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if (sig_block->version != 0) {
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ESP_LOGE(TAG, "image has invalid signature version field 0x%08x", sig_block->version);
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return ESP_FAIL;
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}
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is_valid = uECC_verify(signature_verification_key_start,
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image_digest,
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DIGEST_LEN,
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sig_block->signature,
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uECC_secp256r1());
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return is_valid ? ESP_OK : ESP_ERR_IMAGE_INVALID;
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}
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