1. Bishop: Chapter 10 Key Management

10. Needham-Schroeder 1. Alice Cathy Alice || Bob || r 1 2. Alice Cathy { Alice || Bob || r 1 || k s || { Alice || k s } k B } k A 3. Alice Bob { Alice || k s } k B 4. Alice Bob { r 2 } k s 5. Alice Bob { r 2 – 1 } k s

18. The Protocol 1. Alice Bob n || Alice || Bob || { r 1 || n || Alice || Bob } k A 2. Cathy Bob n || Alice || Bob || { r 1 || n || Alice || Bob } k A || { r 2 || n || Alice || Bob } k B 3. Cathy Bob n || { r 1 || k s } k A || { r 2 || k s } k B 4. Alice Bob n || { r 1 || k s } k A

27. Protocol 1. user Cathy user || TGS Cathy 2. user { k u , TGS } k u || T u , TGS 3. user TGS service || A u , TGS || T u , TGS 4. user TGS user || { k u , s } k u , TGS || T u , s 5. user service A u , s || T u , s 6. user service { t + 1 } k u , s

34. Man-in-the-Middle Attack (in key exchange using public keys) Alice Cathy send Bob’s public key Eve Cathy send Bob’s public key Eve Cathy e B Alice e E Eve Alice Bob { k s } e E Eve Bob { k s } e B Eve intercepts request Eve intercepts message