Initiator                     Responder
---------------------------------------------------------------------
HDR(IKE_SA_INIT), SAi1(.. ADDKE*...), --->
KEi(Curve25519), Ni, N(IKEV2_FRAG_SUPPORTED),
N(INTERMEDIATE_EXCHANGE_SUPPORTED)
  Proposal #1
    Transform ECR (ID = ENCR_AES_GCM_16,
                   256-bit key)
    Transform PRF (ID = PRF_HMAC_SHA2_512)
    Transform KE (ID = Curve25519)
    Transform ADDKE1 (ID = PQ_KEM_1)
    Transform ADDKE1 (ID = PQ_KEM_2)
    Transform ADDKE2 (ID = PQ_KEM_3)
    Transform ADDKE2 (ID = PQ_KEM_4)
    Transform ADDKE2 (ID = NONE)
                         <--- HDR(IKE_SA_INIT), N(NO_PROPOSAL_CHOSEN)