Which AWS service is designated for user authentication and authorization specifically for OAuth 2.0?

Amazon Cognito is designed specifically for user authentication and authorization, and it fully supports the OAuth 2.0 protocol. This service is particularly useful for managing user sign-ups, sign-ins, and access control, making it straightforward to integrate with web and mobile applications.

By utilizing Amazon Cognito, developers can easily enable secure access to their applications through features such as user pools for authenticating users and identity pools for granting permissions to access AWS resources. With its built-in support for OAuth 2.0, Amazon Cognito allows for the creation of access tokens and id tokens, which are essential for implementing authorization flows in applications. This makes it an optimal choice for applications that require user authentication via social identity providers, like Google or Facebook, as well as custom authentication systems.

The other services mentioned do not primarily focus on user authentication and authorization through OAuth 2.0. AWS IAM, for instance, is more about managing access permissions for AWS services and resources, while the AWS Directory Service facilitates identity management using LDAP or Microsoft Active Directory rather than focusing on OAuth protocols. AWS Secrets Manager is designed for managing sensitive information, like API keys and secrets, but does not handle user authentication directly. Thus, Amazon Cognito stands out as the best solution for this