# Auth & API keys
The Rust SDK now targets server-side and trusted environments. Use a **secret API key** or a backend-issued customer bearer token.
## API key listing (server-side)
```rust
use modelrelay::{Client, Config};
#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
let client = Client::new(Config {
api_key: Some(std::env::var("MODELRELAY_API_KEY")?),
..Default::default()
})?;
let keys = client.api_keys().list().await?;
for key in keys {
println!("{} ({})", key.redacted_key, key.kind);
}
Ok(())
}
```