The network that hides both ends
Tor is the only way in or out of Aphotic. Below is what it does, without the mystique.
Why Tor at all
Encryption hides what you say. Tor hides everything around it.
Encryption protects the words in a message. Somebody watching the network still sees who is talking to whom, at what times, how often, and where the server is. For most people who might come after you, that pattern is worth more than the words.
Tor goes after exactly that. Your internet provider can see that you use Tor and nothing about what for. Our server never learns your IP address. And because the Aphotic server exists only inside Tor, you never learn where it is either.
Onion routing
Three layers, three relays: no relay sees the whole picture
Your phone wraps every packet in three layers of encryption, one for each computer on the way. Each of those computers, called relays, peels off exactly one layer and learns only two things: where the packet just came from, and where it goes next. The first one knows who you are but not where you're going, and the last one knows the destination but not who you are, so nobody in the chain holds both halves.
first( second( meeting point( your message )))
- No single relay can connect the sender to the destination
- The relays are run by thousands of independent volunteers around the world
- Your route through them is thrown away and rebuilt roughly every ten minutes
Circuits
Guard, middle, exit: why Aphotic never uses an exit
An ordinary Tor route ends with an exit relay, the machine that steps back out onto the normal internet to fetch a website for you. That last hop can see the traffic leaving, which makes it the most watched and most attacked position in Tor's design. Your first hop stays the same for weeks. If it changed constantly you'd eventually land on a hostile one by chance, so Tor picks a vetted one and sticks with it.
Aphotic traffic never leaves the Tor network, because our server lives inside it. An Aphotic connection has no exit hop, which means the most-watched position in Tor is missing from it.
Two circuits that meet in the middle
The Aphotic server never publishes an IP address anywhere. It builds its own route into the Tor network and announces itself only through an encrypted listing. Your app picks a meeting point, builds a three-hop route to it, and the server comes to meet it from the other side.
The two routes are joined into one tunnel, encrypted the whole way. The server's side is one hop longer than yours, because Tor adds a hop whenever the far end of a route was chosen by somebody else, and the extra protection the server runs adds one more. The relay at the meeting point sees nothing but scrambled data going past. Neither side can learn the other's IP address even if it wanted to.
- Tor relays end to end
- 6–7
- exit relays involved
- 0
- IP addresses exchanged
- 0
Tor relays end to end
exit relays involved
IP addresses exchanged
The address
The .onion address is the key
An onion address is 56 characters long because it is the server's public key, written out as text. Reaching the address proves you're talking to whoever holds the matching private key, and there is no way to fake that. No name lookup or certificate authority is involved, so there's nothing to poison and nobody to trick into issuing a bogus certificate.
The server's address is built into the app. You never type it and there's nothing to get wrong. The only thing you enter when you first open Aphotic is your 16-character license key. Later on, Settings > Network lets you move to a different server from the signed list.
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.onion
Built in
Tor ships inside the app
Tor starts on its own when you open Aphotic, so there's no Orbot to install and nothing to configure. You can't switch it off either: the server has no ordinary address, so there would be nothing to fall back to.
Starting cold takes a moment, because Tor has to fetch the list of relays and build its routes before it can find anything. Meanwhile Aphotic shows you what it's doing, line by line:
> Bootstrapped 5% (conn): Connecting to a relay
> Bootstrapped 25% (loading_status): Asking for networkstatus consensus
> Bootstrapped 75% (enough_dirinfo): Loaded enough directory info to build circuits
> Bootstrapped 90% (ap_handshake_done): Handshake finished with a relay to build circuits
> Bootstrapped 100% (done): Done
After the first run, Aphotic keeps that network data, so later starts are much quicker. On a network that blocks Tor outright, the startup stops with a visible failure that you can retry. Support for the bridges that get around such blocks is on the roadmap.
Six machines between you and anyone curious
Tor starts by itself the first time you open the app. The only thing you enter is your 16-character license key.