40 lines
2.4 KiB
Markdown
40 lines
2.4 KiB
Markdown
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# Trinitrix Backend API (TriBA)
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## Basic concept
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The core starts a CBS as its child process and gives it as first Arg a base64 encoded UUID.
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The CBS then connects to the local fs (or namespaced) socket.
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After performing a handshake, which includes exchange of encryption keys, all communication
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between core and CBS is encrypted (AES256-GCM-SIV) and serialized using [MessagePack](https://msgpack.org)
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## Packets
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Post-Handshake communication is structured in packets, which have the following structure in their raw form:
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| Size (bytes) | Type | Content |
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|--------------|-------------------|--------------------------------------------------------------------|
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| 4 | uint32 | The size of the payload. |
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| - | encrypted payload | The AES-GCM-SIV encrypted MessagePack serialization of the packet. |
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A decrypted and deserialized packet looks like this:
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| Size | Name | Type | Content |
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|------|--------|--------|-------------------------------------------------------------------------------------------------------------------|
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| 8 | `id` | uint64 | The ID of _this_ packet. Is expected to be an incrementing counter. |
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| - | `body` | enum | The actual packet date. (this will be better documented, as soon, as I dive into the mPack serialization details) |
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## Handshake
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The handshaking process after connecting to the socket looks as follows:
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1. The CBS sends its ID as 16 raw bytes.
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2. When the ID is not known to the core, it aborts the handshaking process by closing the connection.
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3. The core sends its Public Key for this connection. Again just 32 raw bytes.
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4. The CBS sends its Public Key for this connection.
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5. The core sends a 12 byte nonce value.
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6. __Connection Upgrade:__ From this point on, all communication is structured by packets.
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The packet encryption key is calculated using x25519 Diffie-Hellman and the previously exchanged keys.
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The nonce from step 5 will be used as nonce for all packets.
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7. The CBS sends the `HandshakeUpgradeConnection` packet.
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8. (In here there is going to happen API version information exchange etc.)
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9. The Core responds with `HandshakeSuccess`
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