Cryptography - Alternative representation for Elliptic Curve?

[manumonti]

Hi all,

I'm using nRF52840 Development Kit and Nordic SDK v15.2.0 with soft device v6.1.0

I'm using ECDSA Cryptographic libraries for a BLE related project. I want to transmit some ECDSA signed data and the public key of the signer by BLE advertisements. The algorithm i have thought is secp256r1, or secp256k1 maybe.

I need to reduce the data sent to the minimum. So I saw ellipctic curves has several ways to represent the public key. In Nordic SDK libraries public key is represented with 64 bytes, but there are a "compressed" way: public key can be represented with 32 + 1 bytes.

https://crypto.stackexchange.com/questions/8914/ecdsa-compressed-public-key-point-back-to-uncompressed-public-key-point

Is it possible to use this representation with Nordic SDK?

Thank you in advance,

Manuel Montenegro

[Einar Thorsrud]

Hi,

The nrf_crypto module in the SDK does not include support for point compression.

[manumonti]

Hi Einar,

Thank you for your answer.

Manuel Montenegro