When attacking WEP, one must use a wireless card which supports packet injection. I have two questions about this.
(1) As long as we have a busy network, why would we need packet injection? I thought the sole purpose of packet injection is to increase network traffic. If we already have enough traffic, we should not need injection. In other-wards, why is the packet injection feature made a requirement when it seems to be something optional?
(2) Packet injection seems to be done via ARP packets -- i.e., the attacker sends spoofed ARP packets to the AP. Now, when one sends out an ARP packet, the reply is an ARP packet (and I believe the returned ARP packets are not encrypted). Since ARP packets are not encrypted, how does their generation help speed up the attack? I thought the attack is speeded up by the availability of more encrypted packets as opposed to just the availability of more packets.