feat(esp_image_verify): split image verification out of bootloader_support

components/bootloader_support/include/bootloader_sha_flash.h

@@ -0,0 +1,48 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#pragma once
+
+#include "esp_err.h"
+#include "soc/soc_caps.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** @brief Generates the SHA-256 digest of flash contents between offset and offset+length.
+ *
+ * Reads in MMU-sized chunks, so it handles images larger than the MMU window
+ * (3.2 MB / 50 pages of 64 KB).
+ *
+ * @param[in]  flash_offset  Byte offset in flash.
+ * @param[in]  len           Length of data in bytes.
+ * @param[out] digest        32-byte buffer for the resulting SHA-256 digest.
+ *
+ * @return ESP_OK on success; ESP_ERR_NO_MEM if allocation fails.
+ *
+ * @note Defined in the esp_image_verify component; calling it in builds without
+ *       that component fails at link time with an undefined reference.
+ */
+esp_err_t bootloader_sha256_flash_contents(uint32_t flash_offset, uint32_t len, uint8_t *digest);
+
+#if SOC_SHA_SUPPORT_SHA384 && SOC_ECDSA_SUPPORT_CURVE_P384
+/** @brief Generates the SHA-384 digest of flash contents between offset and offset+length.
+ *
+ * @param[in]  flash_offset  Byte offset in flash.
+ * @param[in]  len           Length of data in bytes.
+ * @param[out] digest        48-byte buffer for the resulting SHA-384 digest.
+ *
+ * @return ESP_OK on success; ESP_ERR_NO_MEM if allocation fails.
+ *
+ * @note Defined in the esp_image_verify component; calling it in builds without
+ *       that component fails at link time with an undefined reference.
+ */
+esp_err_t bootloader_sha384_flash_contents(uint32_t flash_offset, uint32_t len, uint8_t *digest);
+#endif
+
+#ifdef __cplusplus
+}
+#endif