General • Re: Size of HASH_VALUE item in RP2530

The bootrom creates a regular 32 byte SHA-256 hash
* for signature checking, the full 256 bit hash is what is signed (and signature checked)
* HASH_VALUE is only used for standalone hash checking (without signature checking)... in this case you can choose to use < 8 words; i.e. if you only store 1 word, then the first word of the 256 bit hash is checked against that

The boot rom checking the integrity of a boot images with a 32 bit digest is really, really bad.

5.9.2.3. HASH_VALUE item
...
TIP Whilst A SHA-256 hash is 16 words, you can include less (down to 1 word) to save space if you like.

Statistics: Posted by gmx — Mon Dec 09, 2024 5:22 pm