Advantages of SECBOOT_AES128_GCM_AES128_GCM_AES128_GCM vs asymmetric crypto with encrypted Firmware

[Grogu]

There are multiple crypto algorithm supported with SBSFU framework

SECBOOT_AES128_GCM_AES128_GCM_AES128_GCM: Authentication, Integrity, Confidentiality are ensured.

  *                           Authenticate Firmware Metadata using AES128-GCM tag.

  *                           Decrypt Firmware image using AES128-GCM algo.

  *                           Firmware Image Integrity using AES128-GCM tag.

#define SECBOOT_ECCDSA_WITHOUT_ENCRYPT_SHA256        (1U) /*!< asymmetric crypto, no FW encryption           */
 
#define SECBOOT_ECCDSA_WITH_AES128_CBC_SHA256        (2U) /*!< asymmetric crypto with encrypted Firmware     */
 
#define SECBOOT_AES128_GCM_AES128_GCM_AES128_GCM     (3U) /*!< symmetric crypto 

I am not an expert on crytpo so hoping someone can educate me asymmetric crypto with encrypted Firmware vs AES GCM in context of SBSFU

[Bubbles · Accepted solution]

Hi @Community member​ ,

advantages of GCM are in performance (especially if no HW accelerator of asymmetric crypto is available on the chip) and more compact implementation. This authenticated encryption has some limitations, for example that security weakens with long messages.

ECC is superior in robustness, more flexible, but also more demanding for resources.

Anyway both are implementations of publicly known standard algorithms.

BR,

J