Appendix AC — Nostr Bridge Specification (EventBus over Nostr)

AC.1. Purpose

Full specification of the nostr-bridge-d daemon, providing transparent integration of the local EventBus with the decentralized Nostr network.

AC.2. Implementation in Rust (nostr-sdk 0.33)

// Cargo.toml
[dependencies]
Nostr-sdk = { version = "0.33", features = ["nip44", "socks"] }
Tokio = { version = "1.0", features = ["full"] }
Serde = { version = "1.0", features = ["derive"] }
Serde_json = "1.0"
Log = "0.4"

// main.rs (fragment)
Use nostr_sdk::prelude::*;
Use std::str::FromStr;

Pub struct NostrBridge {
    Client: Client,
    Identity: Keys,
    Local_rx: tokio::sync::broadcast::Receiver<InternalEvent>,
}

Impl NostrBridge {
    Pub async fn new(secret_key: &str, relays: Vec<String>, local_rx: …) -> Result<Self> {
        Let identity = Keys::from_sk_str(secret_key)?;
        Let proxy = std::net::SocketAddr::from_str("127.0.0.1:9050")?;
        Let opts = Options::new().proxy(proxy).wait_for_send(true);
        Let client = Client::with_opts(&identity, opts);
        For relay in relays {
            Client.add_relay(relay).await?;
        }
        Client.connect().await;
        Ok(Self { client, identity, local_rx })
    }

    Async fn broadcast_to_nostr(&self, event: InternalEvent) -> Result<()> {
        Let kind = match event.topic.as_str() {
            "economic" => Kind::Custom(20001),
            "security" => Kind::Custom(20002),
            "infra" => Kind::Custom(20003),
            "command" => Kind::Custom(20000),
            _ => Kind::Custom(20003),
        };
        Let payload = serde_json::to_string(&event.payload)?;
        Let encrypted = nip44::encrypt(
            &self.identity.secret_key()?,
            &receiver_pubkey, // from configuration
            Payload,
            Nip44::Version::V2,
        )?;
        Let nostr_event = EventBuilder::new(kind, encrypted, [])
            .to_event(&self.identity)?;
        Self.client.send_event(nostr_event).await?;
        Ok(())
    }
}

AC.3. Example of Event Encapsulation

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AC.4. Deployment of a Hidden .onion Relay

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