Re: [quicwg/base-drafts] Looping with multiple Retry packets (#1451)

[MikkelFJ <[e-mail]>]

I believe the initial packet should always contain 1280 bytes, also after RETRY, otherwise an attacker might learn how to construct retry SCID's and use a second flight INITIAL as a DDoS vector.

The initial key should also be derived based on the NONCE in the current INITIAL packet. So, as I suggested before, it makes sense to carry the NONCE separately and make the initial DCID empty - at cannot be used for safe routing anyway and it simplifies routing logic because LB's don't have to know if the INITIAL DCID is random or not, they just have to take a decision based on emptiness.

The source SCID cannot be used as that NONCE without adding complexity to the clients LB infrastructure in a P2P server configuration. So I believe the NONCE should be a separate field. And it will not waste any space if the premise holds that all initial packets must be 1280 to prevent attacks.

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