Question on Kyber Encryption (Key Gen)

[Vincent Cozzo]

Hi GPG Users/Developers,

I am doing research on Post Quantum Cryptography, and I had a question
about the GPG 2.5.1 development release, since I read that it
allegedly features an implementation of Kyber.

>From analyzing the codebase (g10/keygen.c), it is clear that the only
way to generate a Kyber public key is to add a _subkey_ to an existing
ECC key (right?).

But whenever I try to test this out (by creating a new ECC Key Pair
and then edit it by adding a subkey with the numerical code 16), I
keep getting the error:
```
gpg: agent_genkey failed for second algo: Invalid public key algorithm
gpg: Key generation failed: Invalid public key algorithm
```

I see that `generate_subkeypair` calls ask_algo, which sets the algo
parameter equal to PUKEY_ALGO_KYBER, and then delegates to `do_create`
which calls `gen_kyber`... but I am having trouble finding where this
particular error message is output. Could anyone help shed light on
where this is failing? What "base Key" do I need to make in order to
satisfy the "public key algorithm" requirement?

Thanks,
-Vince