Suppose that Alice and Bob share a 4-digit PIN number, X. To establish a shared symmetric key, Bob proposes the following protocol: Bob will generate a random key K that he will encrypt using the PIN number X, that is, E(K, X). Bob will send E(K, X) to Alice, who will decrypt it using the shared PIN number X to obtain K. Alice and Bob will then use the symmetric key K to protect their subsequent conversation. However, Trudy can easily determine K by a brute force attack on the PIN number X, so this protocol is insecure.
Modify the protocol to make it more secure. Note that Alice and Bob only share the 4-digit PIN number X and they do not have access to any other symmetric key or public keys. Hint: Use Diffie-Hellman.
Consider the Diffie-Hellman key exchange protocol. Suppose that Alice sends her Diffie-Hellman value, g a mod p, to Bob. Further, suppose that Bob wants the resulting shared secret to be a specific value X. Can Bob choose his Diffie-Hellman value so that, following the protocol, Alice will compute the shared secret XI If so, provide precise details and if not, why not?
Try it now!
How it works?
Follow these simple steps to get your paper done
Place your order
Fill in the order form and provide all details of your assignment.
Proceed with the payment
Choose the payment system that suits you most.
Receive the final file
Once your paper is ready, we will email it to you.