Flash Size of MBEDTLS encryption module

[APasks]

Hello.

We are currently using MBEDTLS to handle DIFFIE HELMAN and AES. We have disabled all unused curves and modules, as suggested in documentation. Still the size of library on flash is ~ 75KB. We find that very costly and would like to reduce the flash size. We are using nrf5 SDK 17.1.0 with S132 on nRF52832.

Is there any way to reduce the size of flash program while still using?

Thank you.

[Sigurd Hellesvik]

Hi,

mbed TLS use a lot of application flash.

Have you tried to use our CryptoCell module for AES and Diffie Hellman instead?
From Cryptography library - nrf_crypto, it looks like it supports AES and multiple different Diffie Hellman curves.

Since CryptoCell310 is a hardware peripheral, it will likely use less application flash than mbed TLS.

Regards,
Sigurd Hellesvik

[APasks]

From what I can see in documentations CC310 is only available for nRF52840.

Is it possible to use it on nRF53832?

We used micro ECC for Diffie Hellman and it drastically decreased flash size.

[Sigurd Hellesvik]

Hi,

APasks said:

From what I can see in documentations CC310 is only available for nRF52840.

You are of course right, I read the chip number wrong.

The CC310 is not available for the nRF53832.

APasks said:

We used micro ECC for Diffie Hellman and it drastically decreased flash size.

Good to hear that you figured it out!

Let me know if you have any other questions

Regards,
Sigurd Hellesvik

[Emil Lenngren]

If ECC is what you're after, I can also recommend my library at https://github.com/Emill/P256-Cortex-M4. It is faster than micro-ecc and I think the code size is smaller as well.