nats.docs/developing-with-nats/security/creds.md

Authenticating with a Credentials File

The 2.0 version of NATS server introduced the idea of JWT-based authentication. Clients interact with this new scheme using a user JWT and the private key from an NKey pair. To help make connecting with a JWT easier, the client libraries support the concept of a credentials file. This file contains both the private key and the JWT and can be generated with the nsc tool. The contents will look like the following and should be protected because it contains a private key. This creds file is unused and only for example purposes.

-----BEGIN NATS USER JWT-----
eyJ0eXAiOiJqd3QiLCJhbGciOiJlZDI1NTE5In0.eyJqdGkiOiJUVlNNTEtTWkJBN01VWDNYQUxNUVQzTjRISUw1UkZGQU9YNUtaUFhEU0oyWlAzNkVMNVJBIiwiaWF0IjoxNTU4MDQ1NTYyLCJpc3MiOiJBQlZTQk0zVTQ1REdZRVVFQ0tYUVM3QkVOSFdHN0tGUVVEUlRFSEFKQVNPUlBWV0JaNEhPSUtDSCIsIm5hbWUiOiJvbWVnYSIsInN1YiI6IlVEWEIyVk1MWFBBU0FKN1pEVEtZTlE3UU9DRldTR0I0Rk9NWVFRMjVIUVdTQUY3WlFKRUJTUVNXIiwidHlwZSI6InVzZXIiLCJuYXRzIjp7InB1YiI6e30sInN1YiI6e319fQ.6TQ2ilCDb6m2ZDiJuj_D_OePGXFyN3Ap2DEm3ipcU5AhrWrNvneJryWrpgi_yuVWKo1UoD5s8bxlmwypWVGFAA
------END NATS USER JWT------

************************* IMPORTANT *************************
NKEY Seed printed below can be used to sign and prove identity.
NKEYs are sensitive and should be treated as secrets.

-----BEGIN USER NKEY SEED-----
SUAOY5JZ2WJKVR4UO2KJ2P3SW6FZFNWEOIMAXF4WZEUNVQXXUOKGM55CYE
------END USER NKEY SEED------

*************************************************************

Given a creds file, a client can authenticate as a specific user belonging to a specific account:

{% tabs %} {% tab title="Go" %}

nc, err := nats.Connect("127.0.0.1", nats.UserCredentials("path_to_creds_file"))
if err != nil {
    log.Fatal(err)
}
defer nc.Close()

// Do something with the connection

{% endtab %}

{% tab title="Java" %}

Options options = new Options.Builder().
            server("nats://localhost:4222").
            authHandler(Nats.credentials("path_to_creds_file")).
            build();
Connection nc = Nats.connect(options);

// Do something with the connection

nc.close();

{% endtab %}

{% tab title="JavaScript" %}

// credentials file contains the JWT and the secret signing key
let credsFile = path.join(confDir, 'credsfile.creds');

let nc = NATS.connect({
    url: server.nats,
    userCreds: credsFile
});

{% endtab %}

{% tab title="Python" %}

nc = NATS()

async def error_cb(e):
    print("Error:", e)

await nc.connect("nats://localhost:4222",
                 user_credentials="path_to_creds_file",
                 error_cb=error_cb,
                 )

# Do something with the connection

await nc.close()

{% endtab %}

{% tab title="TypeScript" %}

// credentials file contains the JWT and the secret signing key
let credsFile = path.join(confDir, 'credsfile.creds');

let nc = await connect({
    url: server.nats,
    userCreds: credsFile
});

{% endtab %} {% endtabs %}