CMPS381 Applied Cryptography - Project

Backend usage

The following code already exists in the secure_messaging.py. Do python secure_messaging.py to see the result.

I have made sure that the data sent to the frontend are in str's (of hex nibbles) and expect those coming from the frontend in that format as well (except for sign_len which should be an int).

from secure_messaging import User

user1 = User("President Biden")
user2 = User("Sheikh Tamim")

# retrieving each other's public key
user1.other_public_key = user2.key.public.hex()
user2.other_public_key = user1.key.public.hex()

# let's say user1 initiates the key exchange
assert user1.key.shared is None and user2.key.shared is None # proving no shared key initially
encrypted_shared_key = user1.send_key_exchange()
user2.receive_key_exchange(encrypted_shared_key)
# by this point, both of the users should have the same shared key
assert user1.key.shared is not None and user1.key.shared == user2.key.shared # proving secret key is shared

# user2 wants to send a message
message = "Dear President Biden, Enter Islam and you will be safe."
ciphertext, nonce, sign_len = user2.encrypt(message)

# user1 receives and decrypts it 
# if success = integrity, authencity and non-repudiation
# if error = at least one of them is not met
received_message = user1.decrypt(ciphertext, nonce, sign_len)
assert message == received_message # proving the sent message is the same as the received one
print(user1.name, "received a message from", user2.name, ":", received_message)

Frontend usage

Everything you need to build a Svelte project, powered by create-svelte;

Creating a project

If you're seeing this, you've probably already done this step. Congrats!

# create a new project in the current directory
npm init svelte@next

# create a new project in my-app
npm init svelte@next my-app

Note: the @next is temporary

Developing

Once you've created a project and installed dependencies with npm install (or pnpm install or yarn), start a development server:

npm run dev

# or start the server and open the app in a new browser tab
npm run dev -- --open

Building

Before creating a production version of your app, install an adapter for your target environment. Then:

npm run build

You can preview the built app with npm run preview, regardless of whether you installed an adapter. This should not be used to serve your app in production.

Final complete version

Visit crypto-app on dockerhub