CY-702-D Multimedia Security and Forensics - Nov 2023 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aExplain how the Discrete Cosine Transform (DCT) is used in multimedia compression and why is it considered lossy?
   How to answer

   • Define DCT and its role in transform coding (e.g., JPEG/MPEG).
   • Explain block-wise transform, energy compaction into low-frequency coefficients.
   • Explain quantization / discarding high-frequency coefficients steps.
   • Reason for lossy nature: irreversible quantization and data loss.
2. 7 Marks
   bWhat is meant by the statement that "various industries merge to form interdisciplinary vendors of multimedia information"? Provide examples of such mergers.
   How to answer

   • Interpret the statement about convergence of industries.
   • Explain interdisciplinary vendors of multimedia information.
   • Give examples of mergers e.g., computing, telecom, entertainment, consumer electronics.
   • Significance for multimedia systems.
3. 7 Marks
   aExplain different aspects of virtual reality as a multimedia application.
   How to answer

   • Define virtual reality as multimedia application.
   • Describe aspects: immersion, interactivity, sensory feedback, 3D graphics/audio/video.
   • Explain hardware/software components.
   • Give example applications.
4. 7 Marks
   bDiscuss the importance of resource management in ensuring QoS in multimedia applications. What types of resources are typically managed?
   How to answer

   • Define QoS and need for resource management.
   • Explain importance: bandwidth, delay, jitter guarantees.
   • List typically managed resources: CPU, memory, network bandwidth, buffers.
   • Explain allocation/scheduling/admission control.
5. 7 Marks
   aDiscuss various factors which affect the Quality of Service (QoS) in multimedia delivery.
   How to answer

   • Define QoS in multimedia delivery.
   • Discuss factors: bandwidth, latency, jitter, packet loss, throughput.
   • Discuss network, server and client-side factors.
   • Impact on audio/video quality.
6. 7 Marks
   bExplain how operating systems utilize layers to efficiently manage hardware resources, provide examples of layers in modern operating systems?
   How to answer

   • Explain layered OS architecture concept.
   • Describe layers: hardware, kernel, device drivers, system services, API/application.
   • Explain how layers abstract and manage resources efficiently.
   • Give examples in modern OS like Windows/Linux.
7. 7 Marks
   aExplain the difference between active and passive security attacks in multimedia systems.
   How to answer

   • Define active vs passive attacks.
   • Compare on basis: modification vs eavesdropping, detection difficulty, examples.
   • Give multimedia-specific examples: tampering, DoS vs sniffing, traffic analysis.
   • Explain security implications.
8. 7 Marks
   bWhat is multimedia authentication and why is it important in ensuring the integrity of multimedia content? Provide examples of authentication mechanisms.
   How to answer

   • Define multimedia authentication and integrity.
   • Explain importance against tampering, forgery, piracy.
   • Describe mechanisms: digital signatures, hashes, watermarks, certificates.
   • Give examples for image/audio/video.
9. 14 Marks
   Imagine you are a photographer who wants to protect your digital images from unauthorized use? You have the option to use either visible or invisible watermarks. How would you decide which type of watermark to use for each of the following scenarios and what factors would influence your decision? Explain your reasoning for each scenario.

   1. i)Sharing high-quality photos on your professional portfolio website.
   2. ii)Uploading images to a stock photography platform for sale.
   3. iii)Sending low-resolution preview images to potential clients for review.
   How to answer

   • Define visible vs invisible watermarks with properties.
   • Analyze each scenario: portfolio, stock sale, low-res preview.
   • Recommend watermark type per scenario with factors: deterrence, aesthetics, robustness.
   • Justify decision factors: visibility, removal resistance, quality.
10. 7 Marks
    aExplain the process of digital evidence extraction, including the steps involved and the tools used.
    How to answer

    • Outline evidence extraction phases: identification, preservation, collection, examination.
    • Describe steps: write-blocking, imaging, hashing, chain of custody.
    • List tools: EnCase, FTK, Autopsy, dd, etc.
    • Explain documentation and integrity verification.
11. 7 Marks
    bIn the context of multimedia evidence handling, explain the significance of metadata in digital forensics. How can metadata assist in the authentication and analysis of multimedia files?
    How to answer

    • Define metadata and types: EXIF, ID3, file system metadata.
    • Explain significance in forensics: origin, timestamps, device info.
    • Explain use in authentication: detecting tampering/inconsistencies.
    • Explain use in analysis: timeline, linkage, search.
12. 7 Marks
    aHow can printer and scanner forensics play a role in identifying and mitigating these risks? Provide a case study to illustrate your points.
    How to answer

    • Explain printer/scanner forensic traces: banding, dots, noise, sensor patterns.
    • Explain identification and mitigation of forgery/counterfeit risks.
    • Describe examination techniques and tools.
    • Provide illustrative case study of document forgery detection.
13. 7 Marks
    bHow can digital forensics experts authenticate and validate audio recordings in a legal context? Discuss.
    How to answer

    • Define legal authentication requirements for audio.
    • Explain techniques: waveform/spectrogram analysis, ENF, metadata, hash.
    • Explain chain of custody and expert testimony.
    • Discuss tampering detection: edits, splicing, enhancement validation.
14. 14 Marks
    Write short note (on any two):

    1. a)The Need for computer forensics
    2. b)Protocols
    3. c)Multimedia Content Forensics
    How to answer

    • For each chosen topic give definition and need/scope.
    • Explain key concepts, protocols/methods and applications.
    • Include diagrams/examples where relevant.
    • Conclude with forensic/security significance.