Draft: initial cryptography implementation

[maurges]

Please check that it's sane and there are no silly errors

[survived]

Would you consider moving all parameters into separate trait Ciphersuite? Something like:

pub trait Ciphersuite {
    type Curve: generic_ec::Curve;
    type Mac: digest::Mac + cipher::KeyInit;
    type Enc: cipher::KeyIvInit + cipher::StreamCipher;
    type HmacDigest: digest::Digest;
    type SecretKey;
    
    fn secret_key_to_scalar(sk: &Self::SecretKey) -> NonZero<SecretScalar<Self::Curve>>;
}

then everything can be parametrized just by this one trait.

[survived]

@maurges btw I can't actually review the PR / mark threads as resolved. Can you add research group as admins?

[survived]

@maurges what do you think about ciphersuite trait?

[maurges]

I think it's a neat idea, although my vision for this library was to be monomorphic: the primary interface should be generic_ecies::some_ciphersuite_module. Kind of similar to the nacl library.