getSharedSecret()

[mikedilger]

Is there a way I can replicate https://github.com/paulmillr/noble-secp256k1 getSharedSecret() function using this crate?

If not, can we add a function for that? It's used in the nostr protocol. It's basically a normalized public key multiplied by a normalied private key, but the devil is in the details (and if I try to write it, there will be even more devils in the details).

[tarcieri]

You're looking for https://docs.rs/k256/latest/k256/ecdh/fn.diffie_hellman.html

[mikedilger]

Thanks. Unfortunately I can't get a SecretKey from a schnorr::SigningKey on which to run .to_nonzero_scalar(), and I can't get a NonZeroScalar directly from a schnorr::SigningKey even though it is right in there privately. And if I try to go into bytes and back let field_bytes = signing_key.to_bytes(); let nonzero_scalar = NonZeroScalar::from_repr(field_bytes) the bounds are not satisfied.

Can we have a schnorr::SigningKey.inner() or something?

[tarcieri]

#690 adds an accessor method, however it's on the v0.12 release track and therefore won't be available until the next minor release

[mikedilger]

Thanks! In the meantime I created an identical type into which I transmute.