Reference no: EM132487533

CSCI968 Advanced Network Security - University of Wollongong

Assignment Part 1: Programming

Write (Java or C++) UDP programs to implement a remote login protocol. For simplicity, let us call the programs "Host" and "Client", which are executed by Alice and Bob, respectively.

Alice and Bob share a common password PW, which contains 8 alphanumeric characters. Alice also has a public and privacy key pair pk = (e, N), sk = (d, N) for the plain RSA encryption where N is a 1024-bit Modulus. Alice wants to authenticate Bob for every remote connection established by Bob. This is done through the following identification protocol:

1: B → A: Username

2: A → B: pk, NA

3: B → A: Encpk(H(Username, PW, NA+1))

4: A → B: Success/Fail

In the above protocol, NA is a 128-bit nonce randomly chosen by Alice in each session, H is the SHA-1 hash function and Enc denotes the plain RSA encryption.

Assignment Part 2: Protocol analysis

Question 1. Explain the purpose of using the nonce NA in the protocol.

Question 2. What is the advantage if we replace the plain RSA encryption by a randomised public-key encryption scheme (e.g., the ElGamal encryption)?

Question 3. Suppose we replace the plain RSA encryption by a more secure version (e.g. RSA-OAEP), is the protocol secure against active attackers? Justify your answer.

Question 4. Modify the protocol so that Bob can also authenticate Alice.

Attachment:- Advanced Network Security.rar