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HW AES with X-CUBE-CRYPTOLIB: using DMA?

Question asked by Charles Seldon on Oct 19, 2017
Latest reply on Oct 23, 2017 by Amel N

Hello,

 

I am using the STM crypto library X-CUBE-CRYPTOLIB (there are several libraries and I could not find out which one was recommended so I picked the most recent one) with an STM32F417.

 

I can't find any information about the internal implementation. More specifically, I need to know if the AccHw_ AES routines use DMA. The CRYP_IN DMA stream is (2, 6), but my application requires SDIO on the same stream (I can't use stream (2,3) because it is needed by SPI1_TX).

 

My initial testing shows that the encryption seems to work despite the fact that the SDIO is on and active, but I need to understand *why* does it work and if I can rely on this behaviour.

 

Therefore, I have the following questions:
- Does X-CUBE-CRYPTOLIB uses DMA for the AES encryption?
    - If it does, how can it work in parallel with the SDIO?
    - If it does not, why? Does it uses interrupts? Polling? How can this be optimal?
- Can it be configured and how?

 

Thanks for any information that could help me sort this through.
Charles

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