How to use Cortex-M core as an additonal cryptographic accelerator (i.e., besides CAAM)?

[uthappapj]

Hello everyone,

        My team is exploring the possibility of having the Cortex-M4 core of i.MX7ULP perform certain cryptographic services. We are aware that the CAAM module provides most of the commonly used cryptographic operations. However we have certain additional requirements with regards to encryption/decryption (such as support for AES CTR (counter) mode for encrypting/decrypting audio stream). And we wanted to utilize the Cortex-M4 core to do this in real-time (low latency).

        Is anybody aware of a preexisting library or FreeRTOS (not necessarily though) opensource/commercial project that we can reuse for our aforementioned purpose?

Best regards,

Uthappa

[Bio_TICFSL]

Hello Uthappa,

Job Ring number is an input to the BKEK derivation function only for Secure Memory blobs, not general memory blobs.
And the Job Ring number used is the Job Ring that owns the Secure Memory partition, not the Job Ring number where the blob encapsulation/decapsulation descriptor is run.
So you would have to dedicate one or more job rings to the m4, have the m4 claim one or more Secure Memory partitions, set the access permissions for those partitions to exclude the a7, and use Secure Memory blobs to save the data in the partitions across power cycles.

Regards