Re-calculate the bootloader's SHA256 (#567)

* Re-calculate the bootloader's SHA256

* CHANGELOG.md entry

Author: bjoernQ

CHANGELOG.md

@@ -29,6 +29,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fixed `defmt` parsing when data is read in parts (#503)
 - Use partition table instead of hard-coded values for the location of partitions (#516)
 - Fixed a missed `flush` call that may be causing communication errors (#521)
+- Fix "SHA-256 comparison failed: [...] attempting to boot anyway..." (#567)
 
 ### Changed
 - Created `FlashData`, `FlashDataBuilder` and `FlashSettings` structs to reduce number of input arguments in some functions (#512, #566)

espflash/src/image_format/idf_bootloader.rs

@@ -73,6 +73,13 @@ impl<'a> IdfBootloaderFormat<'a> {
             bytes_of(&header).iter().copied(),
         );
 
+        // re-calculate hash of the bootloader - needed since we modified the header
+        let bootloader_len = bootloader.len();
+        let mut hasher = Sha256::new();
+        hasher.update(&bootloader[..bootloader_len - 32]);
+        let hash = hasher.finalize();
+        bootloader.to_mut()[bootloader_len - 32..].copy_from_slice(&hash);
+
         // write the header of the app
         // use the same settings as the bootloader
         // just update the entry point