A chatting C# application with end-to-end encryption. The main purpuse of application is to deliver solution for secure chatting, where you can be sure your messages will remain private even if server will be misused. The application is now under development. The works on front end hasn't started yet.
Chatovatko is currently tested under Ubuntu 18.04 and Windows 10.
Function overview
- End-to-end encryption
- Backuping encrypted conversations to server
- On live chatting (chat, where messages are not sended, but chat textbox is cloned to recepient)
- Multiplatform client app (UWP/Windows, Android)
- Multiplatform server app (Windows, Linux)
Releases
The last release is 0.3.1. Android app can be downloaded from Google Play. UWP client app isn't available on Microsoft Store and must be sideloaded.
Important technical details
- .NET Core 2.1 used for server-side service and for command-based console application (for testing purpuse)
- .NET Standart 2.0 used for multiplatform client libraries and server-client shared libraries
- Tls 1.2 is used for encrypting communication between server and client and for server verification
- RSA with key size 4096 is used for client verification and sending AES keys
- AES256 used for encrypting messages
- MySql is required as server-side database.
- Sqlite3 is used as client side database
- The project is developed using Visual Studio 2017 and MySql Workbench 8.0
- Also, the project also benefits from Entity Framework Core, Newtonsoft.Json and Pomelo.EntityFrameworkCore.MySql
- SHA256 and SHA1 used for hashing
- Only little endian is supported
Getting started
There is no offical release currently, but you can download git repository and compile. To clone repository, enter to your console:
git clone https://github.com/stastnypremysl/Chatovatko/
For deep technical details, please, visit wiki.
Installation of server
Install MySql 14 and run script Chatovatko/sql/serverBuildScripts/build.sql. It is necessary to have .NET Core 2.1 installed. This manual seems to be useful.
You will need p12 certificate. You can run this script to generate it: Chatovatko/scripts/genarateCert.sh.
Then make a config file. Here is an example for inspiration:
ConnectionString=Server=localhost; database=chatovatko;UID=MyUserName;password=SuperSecretPassword
CertAddress=/mnt/c/keys/private.p12
ServerName=Unforgattable server name
When everything is ready, run server with this command
cd /pathToRepository/Chatovatko/Premy.Chatovatko/Premy.Chatovatko.Server
dotnet run -c Release -- /otherPath/configFile.txt
Server uses TCP in ports 8470-8472.
Console client
Convenstion
<user> means <user_id> or <user_name>. <thread> means <private_thread_id> or unique <thread_name>, which doesn't contain any space and isn't number.
Installation
As it was in server installation, install .NET Core 2.1 haven't done it already. There are no more prerequsities. Just run:
cd /pathToRepository/Chatovatko/Premy.Chatovatko/Premy.Chatovatko.Client.Console
dotnet run -c Release
First run
There are two inicialization commands:
init new <server_address>
This one will generate new p12 certificate and you will be asked to enter path to save it. It is necessary to keep it SAFE! After that you will be asked to enter your new unique username. Username must be 4 chars at least long and can't be longer than 45 chars. It must match regex ^[a-zA-Z][-a-zA-Z0-9_]+$.
init login <server_address>
If you have your p12 certificate, use this one. If the certificate hasn't been paired with this server already, the entered username will be used for your registration. Otherwise the username will be ignored.
Reset/Relogin
If anything goes wrong, you can always relogin. Run
delete database
and continue as first time.
Casual commands
To exit application, just enter
exit
or
quit
If you want to add comments to your script, please respect this convention
# <comment>
-- <comment>
Online only commands
To open new connection to server, use
connect
If a connection crashed, or you just wanted to disconnect, run
disconnect
Pulling and pushing
Almost all changes are kept in local database. It is necessary to push them on server to finalize them. Analogily the same, you need pull if you want to download all changes, which are on server already. Two magical selfdescribing keywords:
push
pull
Searching and saving contacts
You must find, verify and save a contact to your chain (user's private database), if you want to do any further operation with the user. To do so, please enter to your console
search <user>
Trutification
Before you can send messages to an user, you must trustify him. To do so, enter
trust <user>
This will send server information, that you trust this user and it will generate confirmatory message to user's chain. If you've done this first time, it will also create new AES key and send it encryped to server. The key is for encrypting your messages for the user and for his ability of reading it.
The user must have trustifed you to receive your messages.
If you change your mind and want to untrust some user, just enter to console
untrust <user>
Please, remember the already loaded messages from untrusted users will not be loaded again after database deletion.
Offline commands
These commands will be always executed offline and it is necessary to pull/push to keep everything up-to-date.
Lists
To list all saved users, please enter
ls users
To list all of your threads, please enter
ls threads
Each thread has its own private id (id) and its public id (public_id). Private id is unique only on the client, but public id is unique globally.
Thread writeout can be invoced by
ls messages <thread>
Posts
A new thread can be created by
post thread <user> <name>
Please, keep in mind, a name can't contain double space.
To send new message, please enter
post message <thread> <eof>
......................
....message content...
......................
<eof>
Remember that <eof> cannot contain any space.
Rename
A thread can be renamed by
rename <thread> <name>
The rule for <name> are same as you were creating new thread.
Nickname
User's nick name can be set using command
nickname <user> <nick_name>
A nick name can't contain double space.
Delete
To delete message thread, please enter
delete thread <thread>
Messages can be deleted by
delete message <message_id>
Hash
If you want to compute SHA-256 hash of your certificate, use
hash