triangles_v5/doc/i2p.md

I2P support (SAM v3)

Triangles runs over I2P in addition to Tor, giving the wallet a second anonymous network and a .b32.i2p address shown directly above the .onion address in the status bar.

I2P is on by default and works the same way as the embedded Tor: the wallet auto-launches a bundled i2pd router as a managed child process, enables its SAM bridge, and connects to it. The user does not have to install or configure anything — provided the i2pd binary ships with the wallet.

Shipping the i2pd binary

Like tor.exe, the wallet looks for an i2pd executable in several places and launches the first one it finds:

1. Next to the wallet executable (recommended): i2pd.exe (Windows) / i2pd (Linux/macOS), or in an i2pd/ subfolder beside it.
2. In the data directory (or its i2pd/ subfolder).
3. Common system locations (/usr/bin/i2pd, Homebrew, C:\i2pd\…, etc.).

Get i2pd from https://i2pd.website/ (or your package manager) and place the binary next to the wallet in your build/packaging step. That's the only manual part, and it's a packaging concern, not something the end user does.

If no i2pd binary is found, the wallet logs a notice and continues with Tor only — I2P is strictly additive and never blocks start-up.

What happens at start-up

1. If a SAM bridge is already listening on 127.0.0.1:7656 (e.g. you run your own router), the wallet uses it and does not launch its own.
2. Otherwise it writes i2pd.conf into <datadir>/i2pd/ (SAM enabled, other services off), launches i2pd, and waits for the SAM bridge to come up.
3. The SAM client then loads/creates a persistent destination (<datadir>/i2p_private_key), opens a STREAM session, derives the .b32.i2p address (base32(SHA-256(destination))), accepts inbound I2P streams, and dials outbound .b32.i2p peers.
4. On wallet exit, the SAM session is closed and the i2pd child process is terminated (an external router you started yourself is left running).

The first session takes a little longer while i2pd builds tunnels; the address appears once the bridge is ready.

Options

-i2p                 Enable I2P; auto-launches bundled i2pd (default: 1; -i2p=0 to disable)
-i2psam=<ip:port>    SAM bridge address (default: 127.0.0.1:7656).
                     A non-loopback address disables the bundled router and
                     connects to that external bridge instead.

Checking it

• GUI: the .b32.i2p address sits on top of the .onion in the status bar; click either to copy.
• RPC: getinfo shows toraddress and i2paddress; getnetworkinfo shows toraddress and an i2p object (enabled, active, address, peers).

Notes / limitations

• The address serialization format carries a flag for I2P addresses, so all nodes must run this build to exchange I2P peers; an old peers.dat is discarded.
• i2p_private_key is your stable I2P identity — back it up, don't delete it.
• This was implemented without a build/CI environment here; build and test against a real i2pd before relying on it.