online_security_project/protocol.md
2024-12-01 19:40:22 +02:00

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# The Protocol
All encryptions are made using RSA (key size to be determined), no symmetric encryptions
are used due to messages being short.
## Registration:
- User sends a register request to server `(phone number, RSA public key)`,
giving them a public key and encrypting using the server's public key
- Server sends the user a `Confirm` message & a 6-digit code
- User sends the server the 6-digit code, signed using the key provided at stage 1
(this message is very short and funny, because its a 6-digit code, signed using the
user's private key, and encrypted using the server's public key)
- Server sends a last `Confirm` and the registration process is done
## "Login"
The users dont need to login, as they dont really need to hold a conenction
to the server, only thing that matters is that every message to the server should
be signed with the user's private key, thus the key acts as a form of credentials
## Passing messages
In order to send a message from A to B, A will ask the server for B's key,
A will then encrypt the message using B's key, signed with A, wrapped in a `SendMessage`
request and ultimately signed by A and encrypted using the server's key.
The server will hold on to the message until B will send a `GetMessages` request
to the server.