(d) Write down the authenticated encryption algorithm based on the same design but using different keys for the encryption and the MAC. Explain why the attack from part (c) cannot be done when the authenticated encryption algorithm uses different keys.

) This question is about why one should use different keys when doing encrypt-then-MAC. It is based on Exercise 9.8 in Boneh-Shoup. Suppose Enc is a block cipher with n-bit blocks. We build an authenticated encryption scheme from Enc by using CBC-mode with random IV , and using a MAC also built from CBC-mode. So an encryption of an n-bit message m is a triple (c0, c1, t) where c0 = IV , c1 = Enck(IV ⊕ m), and t = Enck(Enck(c0) ⊕ c1). (a) Write down the operations and checks performed by the authenticated decryption algorithm on input (r, c, t). (b) Write down an encryption of the n-bit zero message and explain why an attacker who asks for encryptions of zero can get many pairs (r, Enck(r)) for random n-bit strings r. (c) Suppose an attacker who does not know k is given r, c = Enck(r) and r 0 , c0 = Enck(r 0 ) for random r = r 0 . Show that (r, r0 ⊕ c, c0 ) is accepted by the decryption algorithm.

Which of the following is a countermeasure to protect against impersonation attacks in public key cryptography?a.Using longer key lengthsb.Encrypting data with symmetric keysc.Changing private keys frequentlyd.Using digital signatures

Question14Max. score: 1.00You are tasked with ensuring that messages being sent and receivedbetween two systems are both encrypted and authenticated. Which of thefollowing protocols accomplishes this?Diffie-HellmanRSASHA-256VPN

1.Question 1Fill in the blank: In the world of AAA security, “authz” is short for _____.1 pointauthoredauthenticationauthoritarianauthorization2.Question 2Which of the following passwords is the strongest for authenticating to a system?1 pointP@w04d!$$L0N6P@ssword!Password!P@55w0rd!3.Question 3Which of the following are valid multi-factor authentication factors? Select all that apply.1 pointSomething you didSomething you areSomething you haveSomething you know4.Question 4Which of the following are examples of "something you have" for multifactor authentication? Select all that apply.1 pointRSA SecureID token PasswordOne-Time-Password (OTP)PING5.Question 5What is a client certificate used for?1 pointTo authenticate the clientTo authenticate the subordinate CATo authenticate the CATo authenticate the server6.Question 6How might a user protect the data on their mobile device if it is lost or stolen? 1 pointRefrain from updating apps Remote wipes Reporting the loss to an IT support specialistKeep a spare device with all your data 7.Question 7What is used to request access to services in the Kerberos process?1 pointClient IDClient-to-Server ticketTGS session key Ticket Granting Ticket 8.Question 8What are the benefits of using a Single Sign-On (SSO) authentication service? Select all that apply.1 pointOne set of credentials for the userReduce overhead of password assistanceReduce time spent on re-authenticating to servicesThe need for multiple passwords9.Question 9Consider the following scenario: A company is utilizing Google Business applications for their marketing department. These applications should be able to temporarily access a user's email account to send links for review. Why should the company use Open Authorization (OAuth) in this situation? 1 pointGain access through a wireless access pointUtilize a Key Distribution Center serverCompatibility with third party appsAdminister multiple network devices10.Question 10What does a Terminal Access Controller Access Control System Plus (TACACS+) keep track of? Select all that apply. 1 pointCommands that were runTrack user authenticationBandwidth and resource usageSystems users authenticated to

Which of the following statements are true about the 802.11 open system authentication method? Each correct answer represents a complete solution. Choose two.This type of question contains radio buttons and checkboxes for selection of options. Use Tab for navigation and Enter or space to select the option.Aoption AIt is a null authentication algorithm.Boption BIt is more secure than shared-key authentication.Coption CIt is a four-way frame exchange.Doption DIt is one of the authentication processes, which allows the network to be considered as a RSN (Robust Security Network).