Crypto backend module used by DFU and Appication

RE: Crypto backend module used by DFU and Appication

Einar Thorsrud — Wed, 12 May 2021 06:41:11 GMT

No, the security will be exactly the same, and the connection will also be established in the exact same way. It is just that the crypto operation done during the Diffie–Hellman key exchange will take slightly more time and consume more power. But this is a one-time operation per pairing so if this is all you use crypto for in your application, it has no practical implications.

RE: Crypto backend module used by DFU and Appication

moon.kim — Tue, 11 May 2021 23:43:10 GMT

Hi,

Thank you for reply

I have one question about this.

Does poor performance mean that the connection may not be possible during pairing? Or does it mean that security is weak?

[quote userid="7377" url="~/f/nordic-q-a/75000/crypto-backend-module-used-by-dfu-and-appication/309205#309205"] If you only use crypto for LESC and DFU, then you could use micro-ecc in the app as well (it will not have as good performance, but that only matters when pairing which is not a common task. And you should expect to see a reduction in application size.[/quote]

RE: Crypto backend module used by DFU and Appication

Einar Thorsrud — Tue, 11 May 2021 11:38:51 GMT

Hi,

[quote user=""]Question 1. Can use the same crypto backend module in bootloader and application?[/quote]

No, you cannot. The crypto module is part of the binary, and is separate for the bootloader and application. Note that micro-ECC is quite small, so you do not have any other real option for the bootloader.

How does your memory layout look? Would it be possible to compress the application a bit to give room to increase the bootloader sizes? Perhaps by using something other than oberon in the application as well? If you only use crypto for LESC and DFU, then you could use micro-ecc in the app as well (it will not have as good performance, but that only matters when pairing which is not a common task. And you should expect to see a reduction in application size.