Amazon Cognito offers two main components for managing user authentication and identity management: User Pools and Identity Pools. Both are used in different scenarios and have distinct purposes. Here’s a comparison to help clarify the differences between them:
Amazon Cognito User Pool:
A User Pool is primarily focused on user authentication, and it provides a user directory that can be used to manage sign-up, sign-in, and user profiles.
Key Features of User Pools:
- User Authentication:
- Provides built-in user registration and sign-in services.
- Handles account creation, login, password recovery, and multi-factor authentication (MFA).
- User Management:
- Stores and manages user profiles.
- You can store custom attributes for each user, such as address, phone number, etc.
- Token Generation:
- Upon successful authentication, Cognito User Pools provide JWT (JSON Web Tokens) for access tokens, ID tokens, and refresh tokens.
- These tokens can be used to authorize access to AWS services, and applications can validate these tokens for user identity.
- User Sign-Up/Sign-In:
- You can set up and customize sign-up and sign-in flows, including adding email/phone verification and password policies.
- Federated Identities:
- Supports authentication via social providers (like Google, Facebook) or enterprise identity providers (like Active Directory via SAML).
- Custom Authentication Flow:
- If needed, you can build a custom authentication flow with AWS Lambda triggers, for example, to add custom user validation, pre-sign-up checks, etc.
- Security Features:
- Built-in support for MFA, email/phone verification, and password policies (minimum length, complexity).
- Supports advanced features like adaptive authentication based on risk (e.g., changing locations, unfamiliar devices).
Use Case for User Pools:
- When you need to manage user registration, authentication, and profile management.
- Ideal for applications that require direct control over user authentication and identity.
Amazon Cognito Identity Pool:
An Identity Pool enables federated identities and allows you to give authenticated users temporary access to AWS resources. It is used to authorize access to AWS services like S3, DynamoDB, or Lambda, based on the identity and permissions of the user.
Key Features of Identity Pools:
- Federated Identities:
- Supports both authenticated and unauthenticated users.
- Allows users to authenticate via Cognito User Pools, social logins (e.g., Facebook, Google), or SAML-based identity providers (e.g., Active Directory).
- Temporary AWS Credentials:
- After authenticating via an identity pool, users are issued temporary AWS credentials (via AWS STS).
- These credentials provide fine-grained access to AWS resources, like allowing a user to read from an S3 bucket or invoke a Lambda function.
- Access Control:
- IAM roles and policies are assigned based on the authenticated identity, enabling control over what AWS resources the user can access.
- Unauthenticated Identities:
- You can enable guest access for users who don’t want to sign in or authenticate but still need limited access to AWS resources.
- Security:
- Access control is managed through IAM roles, which are assigned based on the authenticated identity (either through User Pools or other authentication sources).
- You can configure access policies to specify the AWS services and resources users can access.
Use Case for Identity Pools:
- When you need to allow users to access AWS resources directly, after they have authenticated, via temporary credentials.
- Ideal for applications that need to give users fine-grained access to AWS services or resources (like S3 or DynamoDB) based on their identity.
Key Differences Between User Pools and Identity Pools:
| Feature | User Pool | Identity Pool |
|---|---|---|
| Primary Purpose | User authentication and management | Federated identity management and granting AWS access |
| Use Case | Sign-up, sign-in, and managing user profiles | Accessing AWS resources using temporary credentials |
| Tokens Provided | Provides JWT tokens (ID, Access, Refresh tokens) | Provides temporary AWS credentials (via STS) |
| AWS Integration | Not directly integrated with AWS resources | Direct integration with AWS resources (S3, DynamoDB, Lambda, etc.) |
| Federated Identities | Supports federation from identity providers like Google, Facebook, SAML, etc. | Supports federation from Cognito User Pools, social logins, or external IdPs (Google, Facebook, etc.) |
| IAM Role | No direct IAM role association | Can assign IAM roles to grant access to AWS resources |
| Unauthenticated Access | Not supported | Supports unauthenticated (guest) access to AWS resources |
Common Scenario: Using Both Together:
In many cases, User Pools and Identity Pools are used together:
- User Pools handle the authentication process, verifying who the user is and managing their profile.
- Identity Pools then use the authenticated identity from the User Pool to issue temporary AWS credentials and control the user’s access to AWS services like S3 or DynamoDB.
For example:
- A user authenticates with a Cognito User Pool (using email/password or social login).
- After successful authentication, the user’s identity is passed to an Identity Pool, which then assigns the user temporary credentials (via AWS STS).
- The user can now access AWS services according to the IAM policies attached to the identity pool.