Microsoft Word - U XXXXXXXXXXCWK-MAIN-ASSESSMENT.docx CSECCoursework,2019/2020 Page1 School of Computing Module Coordinator Other lecturers Dr Benjamin Aziz Date Issued 3rd February 2020 Code CSEC...

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Microsoft Word - U30606-1-CWK-MAIN-ASSESSMENT.docx CSECCoursework,2019/2020 Page1 School of Computing Module Coordinator Other lecturers Dr Benjamin Aziz Date Issued 3rd February 2020 Code CSEC / U30606 Title CSEC Coursework Schedule and Deliverables Item Value Format Deadline Lat deadline Ecf deadline Report Total mark = 100 Report overall weight = 40% A single .pdf file submitted through Moodle containing your answer to all tasks. You may use the template provided for your answers 2020-05-13 12:00 [GMT] 2020-06-12 12:00 [GMT] Notes and Advice • The Extenuating Circumstances procedure is there to support you if you have had any circumstances (problems) that have been serious or significant enough to prevent you from attending, completing or submitting an assessment on time. • ASDAC are available to any students who disclose a disability or require additional support for their academic studies with a good set of resources on the ASDAC moodle site • The University takes plagiarism seriously. Please ensure you adhere to the plagiarism guidelines. • Any material included in your coursework should be fully cited and referenced in APA format (sixth edition). Detailed advice on referencing is available from http://referencing.port.ac.uk/ • Any material submitted that does not meet format or submission guidelines, or falls outside of the submission deadline could be subject to a cap on your overall result or disqualification entirely. • If you need additional assistance, you can ask your personal tutor, learning support [email protected] and [email protected] or your lecturers. CSECCoursework,2019/2020 Page2 Coursework-relatedInstructions Please read the following instructions carefully. Answer ALL of the following EIGHT questions. Each question carries its own mark and the total coursework mark is 100. The mark for each question and your coursework is calculated as follows: - If you choose the correct option among the multiple choices for a question, you will be awarded a mark “up to” the maximum of the mark allocated for that question. Your awarded mark for the question will depend on the explanation you provide as to why you made the (correct) choice. If you provide no explanation whatsoever, and you chose the correct answer, you will be awarded ONE mark only for that question. - If you choose any of the wrong answers in a question, you get ZERO for that question. - If you do not answer a question, you will be awarded ZERO for that question. - Always choose only one answer per question. If you choose more than one answer in a single question, you will be awarded ZERO for that question. CSECCoursework,2019/2020 Page3 Question1(Marks:15) CryptographicDataObjects B has just received the following message, which represents a cryptographic data object: {( {(KPbB)KPrS mod KPbS}K1, {|(NB, NA, {{({K2}KPbB, NS)}(G1)KPrA mod NA}K1, {|{({G3}(KPbA)KPrS mod KPbS, G2)}K1|}KPrB)|}KPrA )}KBS The following explains various terms in this object and some of the abbreviations used: • {M}K represents the encryption of some message/data M using the key K • {|M|}K represents the digital signing of some message/data M using the key K • NX represents a nonce (i.e. a fresh and possibly random number used once only) generated by X • KpbX represents the public part of the key pair presumably owned by X • KprX represents the private part of the key pair presumably owned by X • KAB represents a symmetric key shared between A and B • K (or K1, K2, K3 etc.) represents some arbitrary key with no assumptions about its scope • M represents some alphanumeric/textual message with no assumptions • G1, G2, G3 etc. are prime numbers which of the following sets of keys, nonces, numbers, and alphanumeric/textual messages “best” represents B’s knowledge, after B applies any number of possible cryptographic operations to the object above, and assuming that B already has access to key K1 and the public key of any agent: a) KBS , G2 , KPrB b) {(KPbB)KPrS mod KPbS , G2 , KBS , KPrB , {(KPbB)KPrS mod KPbS}K1, NA , NB c) NA , NB d) NA , NB , KBS , KPrB e) {(KPbB)KPrS mod KPbS}K1 , {|(NB, NA, {{({K2}KPbB, NS)}(G1)KPrA mod NA}K1, {|{({G3}(KPbA)KPrS mod KPbS, G2)}K1|}KPrB)|}KPrA , NA , NB , KBS , KPrB , {(KPbB)KPrS mod KPbS f) G2 , NA , NB , G1 , KBS , KPrB g) (KPbB)KPrS mod KPbS , NA , NB , G2 , KBS , KPrB h) (KPbB)KPrS mod KPbS , (G1)KPrA mod NA , NA, NB , G2 , KBS , KPrB i) (KPbB)KPrS mod KPbS , G3 , G2 , KBS , KPrB j) (KPbB)KPrS mod KPbS , NA , NB , G2 , KBS , KPrB , G3 , (KPbA)KPrS mod KPbS k) NB Explain your answer below: CSECCoursework,2019/2020 Page4 Question2(Marks:15) AuthenticationProtocols Consider the following 4-message protocol: 1. A ® S: (B, {(A, K1)}KpbS) 2. S ® B: A 3. B ® S: (A, {(B, K2)}KpbS) 4. S ® A: (B, {K2}K1) Which of the following statements is true, at the end of the protocol, and with regards to the purpose of the protocol: a) Both A and B establish a session key K2, and B is sure of A’s identity b) Both A and B establish a session key K1, and B is sure of A’s identity c) Both A and B establish a session key K1, and A is sure of B’s identity d) Both A and B establish a session key K1, and both B and A are sure of each other’s identity e) Both A and B establish a session key K2, and A is sure of B’s identity f) Both A and B establish a session key K1 g) Both A and B establish a session key K2 h) Both A and B authenticate each other by knowing each other’s identities i) A ends up knowing B’s identity j) B ends up knowing A’s identity k) None of the above l) All of the above Explain your answer below: CSECCoursework,2019/2020 Page5 Question3(Marks:10) Non-RepudiationandAnonymityProtocols For the Zhou-Gollman non-repudiation protocol discussed in the lecture on “Non-Repudiation and Anonymity Protocols”, which one of the following statements is false: a) At time point 4, both A and B can produce evidence to prove that they received K b) At time point 2, both A and B can produce evidence to prove that they received a signed message from the other party c) At time point 0, S cannot prove anything d) At time point 3, B cannot produce evidence to prove that A has access to key K e) At time point 1, A can prove that B is alive f) At time point 4, S can prove that A is alive g) At time point 3, S can produce evidence that that A has access to key K h) At time point 0, A is not alive i) At time point 2, A can produce evidence to prove that B is alive j) At time point 4, the protocol terminates Explain your answer below: CSECCoursework,2019/2020 Page6 Question4(Marks:10) ForwardsSecrecyProtocols Consider the following 4-message protocol: 1. A ® S: (B, {(A, K1)}KpbS) 2. S ® B: A 3. B ® S: (A, {(B, K2)}KpbS) 4. S ® A: (B, {K2}K1) Assume three runs of the above protocol, that we call P1, P2 and P3. If after completion of run P3, K1 is compromised, i.e. it is leaked to some external intruder, how would this impact the forward secrecy property of K2 for all the three runs of the protocol P1, P2 and P3? Choose the right answer: a) Compromising K1 in P3 compromises every other key in all of the three runs of the protocol b) The secrecy of P3.K2 is not compromised, and therefore P2.K2 and P1.K2 would remain secret c) Compromising K1 in P3 compromises P3.K2, and therefore, every other previous version of K1 and K2 are also compromised d) The secrecy of P3.K2 is compromised, but P2.K2 and P1.K2 would remain secret since K1 is refreshed after each run, therefore P3.K1 is different from P2.K1 and is different from P1.K1 e) Even though K1 is compromised in P3, K2 is not compromised in any of the three runs Explain your answer below: CSECCoursework,2019/2020 Page7 Question5(Marks:10) AttacksonSecurityProtocols Consider the following 4-message protocol: 1. A ® S: (B, {(A, K1)}KpbS) 2. S ® B: A 3. B ® S: (A, {(B, K2)}KpbS) 4. S ® A: (B, {K2}K1) And the following attack trace: 1. I(A) ® S: (B, {(A, K)}KpbS) 2. S ® B: A 3. B ® S: (A, {(B, K2)}KpbS) 4. S ® I(A): (B, {K2}K) Which one of these changes to the protocol messages would fix the attack trace above, such as the attack then becomes impossible: a) 3. B ® S: (A, {(B, {K2}KpbA)}KpbS) b) 4. S ® A: (B, {K2, A}K1) c) 2. S ® B: {A}KpbB d) 2. S ® B: B e) 3. B ® S: (A, {(B, {K2}KprS)}KpbS) f) 1. A ® S: {(B, A, K1)}KpbS g) 1. A ® S: (A, {(B, K1)}KpbS) h) 4. S ® A: (B, {K1}K2) i) 4. S ® A: (A, B, {K2}K1) j) 2. S ® B: A, B Explain your answer below: CSECCoursework,2019/2020 Page8 Question6(Marks:10) MutationandType-FlawAttacks Consider the following 4-message protocol between A and B, where (N+1) represents the increment of N: 1. A ® B: (A, {NA}KAB) 2. B ® A: {(NA+1, NB)}KAB 3. A ® B: {NB+1}KAB 4. B ® A: {(K’AB, NA)}KAB Which of the following mutations to messages of the protocol above, would constitute a harmful attack: a) 1. A ® B: (C
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