This is the stencil code for Dropbox. You will implement the functions defined in client.py. Some notes:

• All the code you write should be in client.py; our provided APIs are already imported in client.py for you.
• While you are not permitted to edit the support code files, you may find it helpful to review the comments in the support code files. The crypto library you will use is defined in support/crypto.py. The servers for which you are implementing a client are defined in support/dataserver.py and support/keyserver.py. Finally, support/util.py contains several useful functions for working with bytes. There is example usage of all libraries at the end of each support code file.

To install the support code, you will need to install some dependencies (which are documented in the requirements.txt file). There are many ways to install Python packages. If you are confident that you can install the packages in requirements.txt on your own, you are free to do so however you wish. However, the TAs can only provide direct technical support for the two strategies we recommend here.

Note: This is an experimental installation option for the project. The TAs may not be able to provide technical support for this option; however, if you can get it to work, it's very cool and particularly convenient for working with your partner remotely.

If you don't want to install dependencies locally, you can try an experimental working option where you work on your project code entirely within your browser. To do this:

• Click on the Work in Repl.it button at the top of this file. This will open the repository code in Repl.it, a free online IDE. (You may need to create a Repl.it account if you don't have one already at this point.)
• That's it! Repl.it will open up a virtual machine entirely within your browser and install all of your dependencies into the virtual machine.

You can then run Bash commands in the "Console" on the right-hand side of the screen. You should then test that the installation worked via the Testing the Installation instructions below; you can then run your test cases in the "Console" using the Testing instructions below. To commit changes to the GitHub repository, use the "Version Control" button on the left-hand side of the screen. Refer to the Repl.it Quickstart Guide for more information.

Note that any time you (or your partner) want to work on your project in Repl.it, you should click the "Work in Repl.it" button from the repository page, not directly from your Repl.it account. This allows both you and your partner to work within the same Repl.it instance, which allows you to collaborate "Google Docs"-style.

Note: This strategy applies to only your personal machine! If you are working on a department machine, please see the Department Machines section below.

Follow the instructions in the section below to set up your local environment for working on the project.

First, create a virtual environment using the following strategy:

1. Ensure you are using python3.7 or above by running python3 --version
2. Clone this repo
3. Navigate to the local copy of the repo that you just cloned
4. Inside that directory, run python3 -m venv .env
   • Note that we have added .env/ to the .gitignore so that it will not be pushed to GitHub
5. .env now contains your virtual environment. In order to activate it, run source .env/bin/activate
6. To confirm that the virtual environment has been activated, run which python. The resulting path should end .env/bin/python
7. Once you are done working on the project, you can run deactivate to leave the virtual environment. When you return to the project, you should run source .env/bin/activate again.

Then, while inside of the virtual environment, install the necessary dependencies:

1. Make sure your virtual environment is active
2. Make sure pip is up to date by running pip install --upgrade pip
3. Inside the root directory of your repo, run pip install -r requirements.txt

You can then test your local environment setup with the following comamnds. First, make sure your current working directory is the directory containing your Dropbox repo; also, make sure your virtual environment is activated. Then:

1. Run python client.py

   • It should produce no output. If it exits cleanly, you are good to go.

2. Run python -m support.crypto

   • It should produce no output. If it exits cleanly, you are good to go.

3. Run python -m support.dataserver

   • It should produce the following output:

      random memloc: b'<RANDOM STRING OF BYTES GOES HERE>'
      Specific memloc in hex: b'0000000000000000'
      -------------------
      error testing:
      ERROR: Memloc must be 16 bytes
      exception raised correctly!
      
      ERROR: Datasever can only store raw bytes! You gave val of type <class 'str'>. Please serialize to bytes.
      exception raised correctly!
     

4. Run python -m support.keyserver

   • It should produce the following output:

      Expecting two error messages...
      ERROR: Keyserver tags must be strings, not <class 'int'>
      ERROR: Keyserver keys must of type AsmPublicKey, not <class 'int'>
      Success!
     

You should write tests in test_client.py. There are a few example tests in test_client.py as well as a stencil for your tests. To run the tests you can run

python -m unittest

(This is how we will run our tests against your implementation.)

The tests will be run in alphabetical order. If you run the tests on the stencil code (with no changes), it will run six tests, five of which should fail.

If you are unable to (or don't want to) install the dependencies locally, a properly configured virtual enviroment is available for use on the department machines. To use the virtual enviroment, run source cs166_dropbox_env.