public async Task NewAssymmetric()
        {
            Utils.InitialiseSessionForRandomTestApp();
            var encKeyPairTuple = await Crypto.EncGenerateKeyPairAsync();

            using (var handle = await CipherOpt.NewAsymmetricAsync(encKeyPairTuple.Item1)) {
                Assert.NotNull(handle);
            }
            await Crypto.EncPubKeyFreeAsync(encKeyPairTuple.Item1);

            await Crypto.EncSecretKeyFreeAsync(encKeyPairTuple.Item2);
        }