Reference no: EM13662303
Question 1:
In problem, we will compare the security services that are provided by digital signatures (DS) and message authentication codes (MAC). We assume that Oscar is able to observe all messages sent from Alice to Bob and vice versa. Oscar has no knowledge of any keys but the public one in case of DS. State whether and how (i) DS and (ii) MAC protect against each attack. The value auth (x) is computed with a DS or a MAC algorithm, respectively.
a. (Message integrity) Alice sends a message x = 'Transfer $1000 to Mark° in the clear and also sends auth (x) to Bob. Oscar intercepts the message and replaces "Mark" with "Oscar." Will Bob detect this?
b. (Replay) Alice sends a message x = ^Transfer $1000 to Oscar^ in the clear and also sends auth (x) to Bob. Oscar observes the message and signature and sends them 100 times to Bob. Will Bob detect this?
c. (Sender Authentication with cheating third party) Oscar claims that he sent some message x with a valid auth (x) to Bob, but Alice claims the same. Can Bob clear the question in either case?
d. (Authentication with Bob cheating) Bob claims that he received a message x with a valid signature auth (x) from Alice (e.g.,"Transfer $1000 from Alice to Bob") but Alice claims she has never sent it. Can Alice clear this question in either case?
Hint Decryption is not as hard as you think; use some finesse.
Question 2:
In a public-key system using RSA, you intercept the ciphertext C = 10 sent to a user whose public key is e = 5, n = 35. What is the plaintext M?
1 Consider a Diffie-Hellman scheme with a common prime q = 11 and a primitive root a = 2.
a. If user A has public key Yq = 9, what is A's private key XA?
b. If user B has public key Ya = 3, what is the shared secret key K?
|
Suppose all the energy is transferred to the gas
: A chamber with a fixed volume of 1.0 m 3 contains a monatomic gas at 3.00*10 2 K. The chamber is heated to a temperature of 6.00*10 2 K. This operation requires 20.0 J of heat. (Suppose all the energy is transferred to the gas.) How many gas m..
|
|
What is the speed of the heavier fragment
: An unstable particle at rest breaks up into two fragments of unequal mass. The mass of the lighter fragment is 2.00*10-28 kg, and that of the heavier fragment is 1.64*10-27 kg. If the lighter fragment has a speed of 0.893c after the breakup, what is ..
|
|
Heat energy-how much does temperature increase
: 121.7 J of heat energy are transferred to 38.53 g of mercury. By how much does the temperature increase? (in K) How much heat is needed to raise the temperature of 38.53 g of water with the same amount?
|
|
Show the effective jpy cost of acquiring one usd
: Plains States is considering several hedging alternatives for its receivables to reduce the exchange rate risk arising from the sale - What is the effective JPY cost of acquiring one USD?
|
|
What is the plain text m
: We assume that Oscar is able to observe all messages sent from Alice to Bob and vice versa. Oscar has no knowledge of any keys but the public one in case of DS - Will Bob detect this
|
|
Case study analysis and presentation
: Case study analysis and presentation - Given the Subject Calendar (refer to Subject Outline) and contingent on which case study has been allocated to them, some students may have to study ahead of a lecture and topic being presented in c..
|
|
Distribution of the number of halloween treats
: What is the Z score of a child eating 20 treats - what is the Z score of a child eating 5 treats and faculty or administrative staff member
|
|
Create a transformation matrix
: Find the transformation matrix T02, i.e. T defining {0} with respect to {2}. Learn how to compute the inverse of T20 to get this. Verify that this works by using tranimate to view the movement of frame
|
|
Provide notes as part of the annual report
: You required to provide notes as part of the annual report. For the statement of changes in equity, and the income statement below can you provide notes.
|