circe
mtu 1472

version 1 {
    header {
        u8[64] tunnel_id
    }

    open_tunnel sha512 {
        clear {
            u8[32] ecdh_fragment
            u8[1184] mlkem_pubkey
        }
    }

    ack_open (u8[32] key) sha512 {
        ! poly1305 (fragment_id key frag_remaining)

        clear {
            u8[32] ecdh_fragment
            u8[1088] mlkem_encaps
        }
        chacha20 (0 key) {
            u8[64] identity
            u8[2420] signature
        }
    }

    identify (u8[32] key) sha512 {
        ! poly1305 (fragment_id key frag_remaining)

        chacha20 (0 key) {
            u8[64] identity
            u8[2420] signature
        }
    }

    data (u8[32] key) {
        ! poly1305 (fragment_id key frag_remaining)

        clear {
            u64 sequence_number
        }
        chacha20 (sequence_number key) {
            u8 n_random_bytes
            u8[] payload
            u8[n_random_bytes] padding
        }
    }

    close_tunnel (u8[32] key) {
        ! poly1305 (fragment_id key frag_remaining)

        clear {
            u64 sequence_number
        }
        chacha20 (sequence_number key) {
            u8[64] identity
            u8[2420] signature
        }
    }

    path_challenge (u8[32] key) {
        ! poly1305 (fragment_id key frag_remaining)

        clear {
            u64 sequence_number
        }
        chacha20 (sequence_number key) {
            u8[64] identity
            u8[2420] signature
        }
    }
}