CS558: Network Security

HomeWork 2

 

  1. 9.2 (b,d)
  2. 9.4
  3. 9.5
  4. 9.6
  5. 9.7
  6. 9.8
  7. Consider an active attacker Igor who is capable of inserting packets into connection between Alice and Bob, and can forge the source (and destination; so in particular, Igor can insert packets in such a way that they appear to come from Alice) of these packets. But Igor's ability to spoof is not strong enough to receive packets destined to Alice (or to Bob). How can we defend against Igor (with the least costs)? In particular, do we need signatures and PKI (Public Key Infrastructure: the certificates and the Certificate Authorities to issue them)? What about if Igor joins forces with his friend Keila who can kill any connection (in one or both directions, that is she can make it so that no packets get from Alice to Bob; the spoofed packets from Igor to Bob, pretending to be from Alice, would still get through)?