Describe a man-in-the-middle attack on the Diffie-Hellman protocol where the ad- versary shares a key kA with Alice and a (different) key kB with Bob, and Alice and Bob cannot detect that anything is wrong. (problem 10.3 in the textbook)
Consider the following public-key encryption scheme. The public key is (G, q, g, h) and the private key is x, generated exactly as in the El Gamal encryption scheme. In order to encrypt a bit b, the sender does the following:
(a) Ifb=0thenchoseuniformlyy∈Zq andcomputec1 :=gy andc2 :=hy. The cipher text is ⟨c1, c2⟩.
(b) If b = 1 then choose independent uniform y,z ∈ Zq, compute c1 := gy and c2 := gz and set the ciphertext equal to ⟨c1, c2⟩.
Show that it is possible to decrypt efficiently given knowledge of x.
3. How can CRT be used to speed up RSA decryption? 4. Consider the following key-exchange protocol:
(a) Alice chooses uniform k, r ∈ {0, 1}n, and sends s := k ⊕ r to Bob. (b) Bob chooses uniform t ∈ {0, 1}n, and sends u := s ⊕ t to Alice.
(c) Alice computes w := u ⊕ r and sends w to Bob. (d) Alice outputs k and Bob outputs w ⊕ t.
Show that Alice and Bob output the same key. Analyze the security of the scheme (i.e., either prove its security or show a concrete attack). (problem 10.4 in the textbook)
Delivering a high-quality product at a reasonable price is not enough anymore.
That’s why we have developed 5 beneficial guarantees that will make your experience with our service enjoyable, easy, and safe.
You have to be 100% sure of the quality of your product to give a money-back guarantee. This describes us perfectly. Make sure that this guarantee is totally transparent.
Read moreEach paper is composed from scratch, according to your instructions. It is then checked by our plagiarism-detection software. There is no gap where plagiarism could squeeze in.
Read moreThanks to our free revisions, there is no way for you to be unsatisfied. We will work on your paper until you are completely happy with the result.
Read moreYour email is safe, as we store it according to international data protection rules. Your bank details are secure, as we use only reliable payment systems.
Read moreBy sending us your money, you buy the service we provide. Check out our terms and conditions if you prefer business talks to be laid out in official language.
Read more