---
lang: en
title: 'API docs: security.subject'
keywords: LoopBack 4.0, LoopBack 4, Node.js, TypeScript, OpenAPI
sidebar: lb4_sidebar
editurl: https://github.com/loopbackio/loopback-next/tree/master/packages/security
permalink: /doc/en/lb4/apidocs.security.subject.html
---

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[Home](./index.md) &gt; [@loopback/security](./security.md) &gt; [Subject](./security.subject.md)

## Subject interface

`Subject` represents both security state and operations for a single request. It's the `who` for security.

Such operations include: - authentication (login) - authorization (access control) - session access - logout

**Signature:**

```typescript
export interface Subject 
```

## Properties

<table><thead><tr><th>

Property


</th><th>

Modifiers


</th><th>

Type


</th><th>

Description


</th></tr></thead>
<tbody><tr><td markdown="1">

[authorities](./security.subject.authorities.md)


</td><td markdown="1">


</td><td markdown="1">

Set&lt;[Permission](./security.permission.md)<!-- -->&gt;


</td><td markdown="1">

An array of authorities granted by the user to the client application. One example is {@<!-- -->link https://tools.ietf.org/html/rfc6749\#section-3.3 \| oAuth2 scopes).


</td></tr>
<tr><td markdown="1">

[credentials](./security.subject.credentials.md)


</td><td markdown="1">


</td><td markdown="1">

Set&lt;[Credential](./security.credential.md)<!-- -->&gt;


</td><td markdown="1">

An array of credentials, such as password, access token, or private/public keys.


</td></tr>
<tr><td markdown="1">

[principals](./security.subject.principals.md)


</td><td markdown="1">


</td><td markdown="1">

Set&lt;[TypedPrincipal](./security.typedprincipal.md)<!-- -->&gt;


</td><td markdown="1">

An array of principals. It can include information about the current user, the client application, and granted authorities.

`Subject` represents both security state and operations for a single application user.

Such operations include: - authentication (login) - authorization (access control) - session access - logout


</td></tr>
</tbody></table>