Add native Dosh host trust foundation

src/bin/dosh-auth.rs

@@ -2,13 +2,16 @@ use anyhow::{Context, Result};
 use clap::Parser;
 use dosh::auth::{build_bootstrap, encode_bootstrap, load_or_create_server_secret};
 use dosh::config::load_server_config;
+use dosh::native::{host_public_key, host_public_key_line, load_or_create_host_key};
 
 #[derive(Debug, Parser)]
 struct Args {
     #[arg(long, default_value_t = 1)]
     protocol: u8,
     #[arg(long)]
-    nonce: String,
+    nonce: Option<String>,
+    #[arg(long)]
+    host_key: bool,
     #[arg(long, default_value = "default")]
     session: String,
     #[arg(long, default_value = "read-write")]
@@ -25,8 +28,13 @@ fn main() -> Result<()> {
     let args = Args::parse();
     anyhow::ensure!(args.protocol == 1, "unsupported protocol {}", args.protocol);
     let config = load_server_config(None)?;
+    if args.host_key {
+        let signing_key = load_or_create_host_key(&config)?;
+        println!("{}", host_public_key_line(&host_public_key(&signing_key)));
+        return Ok(());
+    }
     let secret = load_or_create_server_secret(&config)?;
-    let nonce = parse_nonce(&args.nonce)?;
+    let nonce = parse_nonce(args.nonce.as_deref().context("--nonce is required")?)?;
     let size = parse_size(&args.size)?;
     let user = std::env::var("USER").unwrap_or_else(|_| "unknown".to_string());
     let udp_host = args.udp_host.unwrap_or_else(|| "127.0.0.1".to_string());