5193-8-23P SA Code: 6376
SR Code: 4578
RID: 5654 | 12/06/2015
Consider the given scenario in the problem, where Trudy sends the Alice’s certificate, in the step 2.
• In step3, Bob verifies the certificate and identifies that the certificate belongs to Alice and extracts Alice’s public key. Now, Bob generates a Pre-Master secret (PMS) and encrypts it with the Alice’s public key, and sends it to Alice (i.e., Trudy).
• In step4, both sender and receivers has to create Master secret (MS) form PMS and nonces. MS is split to generate two encryption keys and two MAC keys independently. Bob can successfully create these four keys. But, Trudy can’t create Master secrete (MS) and four keys, since Trudy doesn’t know the private key of Alice, and can’t decrypt the PMS. So, Trudy guesses false MAC keys.
• In the step5, bob sends the MAC of messages.
• In the step6, Trudy sends MAC of messages. But these messages fail to pass MAC test. Thus, Bob knows that he is not communicating with Alice.
Therefore, Bob can know that he is not communicating with Alice, in the last step (step6) of SSL hand shake algorithm.
If you found this answer helpful, please upvote and share with other students in your network.