Cryptocell and future products vs MicroECC

[SRA]

So... As I understand it, micro-ECC is a free library that lets you create an ECC private key for signing the SecureDFU that Nordic is using.

The nrf52840 has Cryptocell 310 which has ECC hardware.

To the best of my ability to check this, they are not using compatible curve profiles. Doesn't it make the most sense that one of the curve options used in the hardware reflects the curve options used for Nordic software?

[Turbo J]

Look again, one of the P-256 ECC curves should be compatible to µECC.

[SRA]

www.nordicsemi.com/.../ARM-CryptoCell-310

infocenter.nordicsemi.com/index.jsp

I see that Curve25519 appears in both but according to Nordic only curve(secp256r1) works for DFU.

So is the problem that Nordic is using different terms each time they talk about ECC curves?

[Daniel Wang]

The are curve names chosen by different standards organizations, See appendix A here: tools.ietf.org/.../rfc4492

[SRA]

Ok, so I see that Nordic says use MicroECC to generate a secp256r1 (prime256v1, NIST P-256) pair.... As I understand it from here, NIST 256 p1 isn't even recommended anymore because the NSA may have manipulated it to be weak. en.wikipedia.org/.../Curve25519

Curve25519 is the replacement it seems, but from what I can tell that is NOT supported by SecureDFU as it stands today. So, I ask again, which curve algorithm in Cryptocell is compatible with the secureDFU?

[bjorn-spockeli]

Hi SRA,

at the current moment our Secure DFU implementation only supports the NIST P-256 curve for the simple reason that the Bluetooth Core Specification also uses the P-256 curve for LE Secure Connections. We may add support for other curves, like the Curve25519, in our Secure DFU implementation in the future.

As for Cryptocell, we also currently do not have any support for that in the Secure DFU implementation yet, but that may also change in the future.

Best regards

Bjørn