For each of the following protocols between Alice - a human client - and Bob - a server - decide, whether the protocol is doable, whether it actually authenticates the other party, and whether it is vulnerable to a 1. replay attack 2. reflection attack 3. dictionary attack by (a) somebody snooping (b) somebody impersonating Alice (c) somebody impersonating Bob 4. impersonation of Alice 5. impersonation of Bob

Protocol Evaluation Symbol Explanation A well-known hash function Alice's password KIT Encryption of content T with key K KT Decryption of content T with key K Ni, a, bRandom nonces (assumed to never repeat) TR timeAlice local time at Alice 9, P g is a generator of Zp Document T signed with public / private key pair U, R Protocol Evaluation Symbol Explanation A well-known hash function Alice's password KIT Encryption of content T with key K KT Decryption of content T with key K Ni, a, bRandom nonces (assumed to never repeat) TR timeAlice local time at Alice 9, P g is a generator of Zp Document T signed with public / private key pair U, R