Hi Tomasz,

Sorry for the delay in response.

Although PCA FWU specification allows image compression, TF-M does not implement that feature because the method and place of image compression/decompression is flexible and is up to the target system design and implementation.

Best regards,

Anton

From: Tomasz Jastrzębski via TF-M <tf-m@lists.trustedfirmware.org>
Sent: Friday, January 19, 2024 10:29 AM
To: tf-m@lists.trustedfirmware.org
Subject: [TF-M] Pre-encryption image compression

Hello All,

Does the current TF-M version support image compression before image is encrypted?

Needless to say, compression after the image has been encrypted would not yield reasonable compression ratio.

I am showing that *.bin files, even built with MinSizeRel option, zip-compress with minimum 50% compression ratio so probably this would make sense. Tested with STM32U5 target and GCC.

“PSA Certified Firmware Update API” document in sections 3.1 and 3.2 provides for image compression.

Kind regards,

Tomasz Jastrzębski