How does the station-to-station (STS) protocol defend against the intruder-in-the-middle attack in the Diffie-Hellman protocol?

Suppose Alice and Bob performs the Diffie-Hellman key exchange, using the public parameters with prime and primitive element .

Alice chooses her secret and Bob chooses his secret .

What does Alice send to Bob and why? (You may assume all the arithmetic is correct.)

In this key establishment protocol, 

• interacts with a trusted server and a party .  
• and share a symmetric key , and and share a symmetric key .  
• will choose a key to be shared by and .
• and are random numbers chosen by and respectively.
• We will write to mean encrypting a message using a symmetric key encryption algorithm with key .

The protocol runs as follows:

1. :  , , .
2. : .
3. : .
4. : .
5. : .

Which message, if any, provides confirmation to that the key is possessed by  ?  Pick only one answer.

Suppose Alice has an RSA signature scheme with hash function , with the following values:

and 

Suppose Alice has signing key .

Suppose Alice wants to send Bob a message which has hash value .  She sends and her RSA signature to Bob.

What does Bob do to decide whether to accept this as a valid signature?  

Suppose Alice has an RSA signature scheme, with the following values:

and 

Suppose Alice has signing key .

Pick all the values that must be kept private and known only to Alice. (Marks may be deducted for incorrect choices.)

Pick all the correct statements about a digital signature scheme. (Marks may be deducted for incorrect choices.)

When Alice wants to log into the music streaming service Tunes-R-Us, she signs in using her Security-R-Us credentials.

Who is the relying party? 

The biometric identification for accessing a database has a high Type II/false acceptance error.  What is the main security property that might be compromised for the database?

We assume that Alice has Bob's authentic public key .  The following is an authentication protocol using public key encryption techniques. 

1. Bob Alice : Hi, I am Bob
2. Alice Bob :
3. Bob Alice :

Here is a time-variant parameter and denotes a public key encryption function using key .

Which is the message (and the correct reason) that authenticates Bob to Alice?