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50.005 Computer System Engineering
Information Systems Technology and Design
Singapore University of Technology and Design
Natalie Agus (Summer 2024)

Submission and Demo

If you have reached this stage, you have completed 95% of this assignment, congratulations! One final step is some administrative work that will help your instructors grade your assignments seamlessly.

Please read this section very very carefully and watch the given demo with your full attention.

You are expected to save two additional files each time a client sends a file to the server under [PROJ_ROOT_DIR]:

  1. Client to save encrypted files to /send_files_enc before sending, with the name: enc_[filename], e.g: enc_image.ppm if it is sending image.ppm to the server.
  2. Server to save received encrypted file to client to /recv_files_enc before decrypting, with the name enc_recv_[filename], e.g: enc_recv_image.ppm.

You should have the following files now:

The new files are mainly (names must be exactly these):

1. server_signed.crt, server_private_key.pem # in source/auth
2. ClientWithSecurity[AP|CP1|CP2].py # in source/
3. ServerWithSecurity[AP|CP1|CP2].py # in source/

All other files inside [PROJ_ROOT_DIR]/files directory must remain as per the original files from the previous sections.

You should then make the final commit of all tracked files so far:

git commit -a -m "feat: save to recv_files_enc and send_files_enc before encrypting and before sending"

You can also put your own large files at [PROJ_ROOT_DIR]/files (>100MB) to test internally, but remove it before pushing to Github since it doesn’t allow you to push any single file >100MB. Please do not use git-lfs.

Print Statements

We will not check your program’s stdout during the demo, so you’re free to print whatever you need or want during the development of the assignment.

Following Protocols Closely (1%)

As stated throughout the handout, you need to stick to the protocol strictly, that is to implement each MODE as specified (send or read exactly as specified in the MODE) so that we can run your server scripts against our answer key client scripts and vice versa. This is where the last 1% of your grade come from.

You may easily ensure this by checking your server against another pair’s client, and vice versa. To summarize:

  • Ensure the padding schemes are correct:
    • You (client/server) use either OAEP or PKCS1v15 for encryption and decryption of file data when RSA is used
    • You (server) use PSS for signing
    • Client uses PKCS1v15 to verify server.crt using cacsertificate’s public key because that’s the padding scheme used by our bot
# OAEP
padding.OAEP(mgf=padding.MGF1(hashes.SHA256()), algorithm=hashes.SHA256(),label=None)`
# PKCS1v15
padding.PKCS1v15()
# PSS
padding.PSS(mgf=padding.MGF1(hashes.SHA256()), salt_length=padding.PSS.MAX_LENGTH)
  • Ensure that Fernet is used to generate symmetric key and utilise it (encryption/decryption)
  • AP: Ensure that your MODE 3: sticks to the protocol
    • Client to send TWO messages first upon connection establishment: M1 (int, indicating the size of incoming message M2) and M2 (the message)
    • Server to respond with FOUR messages (two pairs of size int and the corresponding message). This marks the end of MODE 3
    • No other message exchanges allowed in MODE 3
    • Whatever “fix” you do in AP should not change these facts and should be incorporated into MODE 3 protocol
  • CP1: Ensure that in MODE 1, M1 contains the total encrypted file length (sent by client). It is up to you to send M2 repeatedly as 128-byte chunks or to accumulate encrypted 128 byte chunks and then send it all in one single send() socket call.
  • Do not create any new modes. We only expect: MODE 0 - MODE 4.

Not to worry, things will work seamlessly if you stick to these protocols.

Sustainability and Inclusivity

As mentioned previously in Programming Assignment 1, there have been some ongoing initiatives from SUTD as well as the Engineering Accreditation Board to include more elements of Sustainability, Diversity and Inclusivity. As such, we encourage you to consider the impact of your project on sustainability, as well as any consideration for diversity and inclusion (e.g., different cultures, demographic groups, etc).

Here are some suggestions, it is sufficient to fulfil one from each. You may apply it as any part of your assignment, as long as you’re still following the protocols requested closely. It does not have to be part of your code: e.g if you decide to conduct user testing. Simply highlight your attempts clearly in the README file and write future suggestions (if any).

Failure to show attempts to incorporate initiatives to support sustainability and inclusivity results in -3% (penalty) of your overall grades.

Sustainability Ideas

  1. Optimized File Transfer:
    • Description: Design the protocol to transfer files efficiently, minimizing energy consumption and network usage.
    • Task: Implement features such as file compression before transfer and efficient chunking of data to reduce the amount of data sent over the network while still following the protocols closely
  2. Efficient Encryption Practices:
    • Description: Use energy-efficient practices within the constraints of the Python cryptography modules.
    • Task: Choose the most efficient algorithms provided by the Python cryptography library for encryption and decryption to ensure minimal resource usage while maintaining security.
  3. Logging and Monitoring:
    • Description: Include logging and monitoring to track resource usage during file transfers.
    • Task: Implement logging of CPU, memory, and network usage during file transfers, and analyze these logs to identify and optimize inefficient parts of the protocol.
  4. Documentation of Efficient Practices:
    • Description: Document best practices for writing efficient and sustainable code.
    • Task: Include a section in the README detailing efficient coding practices and optimizations used in the project, encouraging the use of these practices in future development.

Inclusivity Ideas

  1. Accessible User Interface:
    • Description: Design the client interface to be accessible to users with disabilities.
    • Task: Ensure the client application supports accessibility features such as keyboard navigation, screen reader compatibility, and customizable text size and color schemes.
  2. Multilingual Support:
    • Description: Provide support for multiple languages in the client and server applications.
    • Task: Implement localization features allowing users to choose their preferred language for interaction with the client and server.
  3. Clear and Inclusive Documentation:
    • Description: Write clear, detailed documentation that is easy to understand for users of all backgrounds.
    • Task: Create comprehensive documentation that includes step-by-step instructions, clear explanations of technical terms, and helpful examples, avoiding jargon.
  4. User-Friendly Error Messages:
    • Description: Provide informative and user-friendly error messages.
    • Task: Implement error messages that are clear, descriptive, and offer actionable steps to resolve issues, ensuring they are easily understandable for all users.
  5. Inclusivity in Testing:
    • Description: Ensure that the system is tested with a diverse range of users.
    • Task: Conduct user testing with individuals from various backgrounds and with different abilities, gathering feedback to improve the inclusivity and usability of the system.

Don’t forget!

Write a README explaining how your implementation considers both sustainability and inclusivity, detailing the specific features and design choices made to address these aspects as part of your submission. Push it to your project repo.

Do NOT break protocol (e.g add additional MODE).

Submission

Simply push to your github classroom repo before the assignment’s due date. No late submission is allowed

README

You are expected to write a clear and succint README file as part of your project submission, detailing the following:

  1. How to compile and run your programs (server and client)
  2. How client can upload multiple files (if you modify the current starter code)
  3. How you have considered sustainability and/or inclusivity in your assignment

Live Demo

You will be asked to clone your project from the github classroom repo (fresh clone).

Sample Demo

The following video shows the expected interaction between Server and Client processes.

Checkoff Procedure

Please be present at your designated slots (refer to course handout) for your PA2 demo. Even though you have submitted your code, we still want to witness your PA2 in person. You will clone your submitted code (fresh) and run it on a different machine. If you’re doing the project alone, our TA/Instructor will be your client.

If all goes well, you should obtain a maximum score of 8% of your overall 50.005 grades.

Here’s the breakdown of PA2 assessment, based on each feature:

  1. Task 1 (3%): Authentication Protocol
  2. Task 2 (2%): Confidentiality Protocol 1 (CP1)
  3. Task 3 (2%): Confidentiality Protocol 2 (CP2)
  4. Following given protocols closely (1%)
  5. Incorporate attempts to support sustainability and inclusivity (failure to do so results in -3%)

Total maximum PA2 grades: 8%.

Prepare everyone

ALL group members must be present. Failure to turn up during demo grants 0 marks for that person missing the checkoff (unless LOA is granted). You must also be able to answer any questions pertaining to your own code, failure to do so grants us the right to revoke the grades for any task even though the demo was successful. We will ask any group members in random, so ensure that everyone’s on the same page before turning up for the demo. Don’t worry, we will ask basic, reasonable questions.

We reserve the right to revoke any marks given for any features even though the demo is working if you fail to answer some basic query about it. Ensure that you have submitted your own work. We also reserve the right to give you 0 marks and report you for further disciplinary action should we find sufficient evidence of plagiarism and report you to OSA for further disciplinary action.