SimpleX chat prototype is a thin terminal UI on top of [SimpleXMQ](https://github.com/simplex-chat/simplexmq) message broker that uses [SMP protocols](https://github.com/simplex-chat/simplexmq/blob/master/protocol).
- Auto-populated recipient name - just type your messages to reply to the sender once the connection is established.
- Demo SMP server available at `smp1.simplex.im:5223` - you can deploy your own server (`smp-server` executable in [simplexmq](https://github.com/simplex-chat/simplexmq) repo).
- No global identity or any names visible to the server(s), ensuring full privacy of your contacts and conversations.
- E2E encryption, with RSA public key that has to be passed out-of-band (see [How to use SimpleX chat](#how-to-use-simplex-chat)).
- Message signing and verification with automatically generated RSA keys.
- Message integrity validation (via including the digests of the previous messages).
- Authentication of each command/message by SMP servers with automatically generated RSA key pairs.
RSA keys are not used as identity, they are randomly generated for each contact. 2048 bit keys are used, it can be changed to 4096-bit in code via [rsaKeySize setting](https://github.com/simplex-chat/simplex-chat/blob/master/apps/dog-food/Main.hs).
Download the chat binary for your system from the [latest stable release](https://github.com/simplex-chat/simplex-chat/releases) and make it executable as shown below.
On Linux, you can build the chat executable using [docker build with custom output](https://docs.docker.com/engine/reference/commandline/build/#custom-build-outputs):
> **Please note:** If you encounter ``version `GLIBC_2.28' not found`` error, rebuild it with `haskell:8.8.4-stretch` base image (change it in your local [Dockerfile](Dockerfile)).
By default, app data directory is created in the home directory (`~/.simplex`, or `%APPDATA%/simplex` on Windows), and SQLite database file `smp-chat.db` is initialized in it.
The default SMP server is `smp1.simplex.im#pLdiGvm0jD1CMblnov6Edd/391OrYsShw+RgdfR0ChA=` (base-64 encoded string after server host is the transport key digest) - it is pre-configured in the app.
The base-64 encoded string in server address is the digest of RSA transport handshake key that the server will generate on the first run and output its digest.
You can still talk to people using default or any other server - it only affects the location of the message queue when you initiate the connection (and the reply queue can be on another server, as set by the other party's client).
Once you have started the chat, use `/add <name1>` to create a new connection and generate an invitation (`<name1>` is any name you want to use for that contact). The add command will output an invitation. Send this invitation to your contact via any other channel.
The invitation has the format `smp::<server>::<queue_id>::<rsa_public_key_for_this_queue_only>`. The invitation can only be used once and even if this is intercepted, the attacker would not be able to use it to send you the messages via this queue once your contact confirms that the connection is established.
The contact who received the invitation should use `/connect <name2> <invitation>` to accept the connection (`<name2>` is any name that the accepting contact wants to use for you).
They would then use `@<name> <message>` commands to send messages. One may also press Space or just start typing a message to send a message to the contact that was the last.
SimpleX chat stores all your contacts and conversations in a local database file, making it private and portable by design, fully owned and controlled by you.
> **Please note:** SQLite foreign key constraints are disabled by default, and must be **[enabled separately for each database connection](https://sqlite.org/foreignkeys.html#fk_enable)**. The latter can be achieved by running `PRAGMA foreign_keys = ON;` command on an open database connection. By running data altering queries without enabling foreign keys prior to that, you may risk putting your database in an inconsistent state.
1. Switch to application level chat protocol. This will allow to separate physical server connection management from logical chat contacts, and to support all common chat functions.
2. SMP queue redundancy and rotation in SMP agent protocol.
3. Symmetric groups support in SMP agent protocol, as a foundation for chat groups.
4. Delivery confirmation in SMP agent protocol.
5. Multi-agent/device data synchronisation - to use chat on multiple devices.
6. Synchronous streams support in SMP and SMP agent protocols, to support file transfer.
7. Terminal chat UI and mobile apps.
8. Scripts for simple SMP server deployment to hosting providers: Linode, Digital Ocean and Heroku.
9. Public broadcast channels.
10. Optional public contact/group addresses using DNS to establish connections, but not using it to send and receive messages - in this way you will keep all your contacts and groups even if you lose the control of the domain.
## Disclaimer
System and protocol security have not been audited yet. As such, it is not advised to use SimpleX chat for high security communications.
