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STM32U585 takes 13 seconds to compute RSA for TLS handshake

RCost.1
Associate

I'm evaluating the STM32U585 TLS performance using the eval board B-U585I-IOT02A. The example application code for MQTT using TLS did not include code on how to load a client key for client authentication but I was able to add that in. The problem I see now is that when using private key the MCU takes 13 seconds to do the RSA computations during the handshake with the server to setup the connection. I track the delay to the following function _nx_crypto_huge_number_mont_power_modulus

Why does this take so long? Does the MCU have hardware acceleration that handles this and is just not being used? Is there something else that I'm doing wrong?

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2 REPLIES 2
Jocelyn RICARD
ST Employee

Hello @RCost.1​ 

yes the STM32U5 version used in the B-U585I-IOT02A embeds a Public Key Accelerator. The implementation of the connection to this accelerator is ongoing and should be available on next release.

Best regards

Jocelyn

Hi Jocelyn,
Is there a schedule for the release or can I be notified when the release happens?
Thanks,
Rui