MSDN Documentation

Authorization Guide

This guide provides an in-depth look at how authorization works within our APIs, ensuring that users and applications only access resources they are permitted to. We will cover the core concepts, common patterns, and best practices for implementing secure authorization in your applications.

Understanding Authorization

Authorization is the process of determining whether a user or application has the necessary permissions to perform a specific action or access a particular resource. This is distinct from authentication, which verifies the identity of the user or application.

Key Concepts

• Permissions: Specific rights granted to a user or application (e.g., "read:user_profile", "write:comments").
• Roles: Collections of permissions assigned to users or groups (e.g., "Administrator", "Editor", "Viewer").
• Scopes: Define the level of access an application requests for a user (often used in OAuth 2.0).
• Policies: Rules that define when access is granted based on user attributes, resource attributes, and environmental conditions.

Common Authorization Models

Role-Based Access Control (RBAC)

RBAC is a widely adopted model where access decisions are based on the roles assigned to users. Each role has a set of permissions. This simplifies management by grouping permissions into roles rather than assigning them individually to users.

if (user.hasRole('Administrator')) {
    // Allow deletion
    deleteUser(userId);
} else {
    // Deny access
    throw new ForbiddenError('Insufficient permissions');
}
                

Attribute-Based Access Control (ABAC)

ABAC offers a more granular approach where access is granted based on a set of attributes associated with the user, the resource, the action, and the environment. Policies are defined using these attributes.

policy: {
    description: "Access to sensitive financial data",
    rules: [
        {
            effect: "allow",
            conditions: {
                AND: [
                    {"attribute": "user.department", "operator": "equals", "value": "Finance"},
                    {"attribute": "environment.currentTime", "operator": "between", "value": ["09:00", "17:00"]}
                ]
            }
        }
    ]
}
                

Implementing Authorization with OAuth 2.0 Scopes

When integrating with our APIs using OAuth 2.0, applications request specific scopes during the authorization flow. These scopes define the granular permissions the application is granted for the user's account.

Common Scopes:

• user.read: Allows reading basic user profile information.
• user.write: Allows updating user profile information.
• data.read.all: Allows reading all available data for the user.
• data.write.sensitive: Allows writing sensitive data on behalf of the user.

When an API request is made, the token will contain the granted scopes. The API endpoint must validate that the token includes the necessary scope for the requested operation.

function handleApiRequest(request) {
    const token = request.headers.get('Authorization');
    const requiredScope = 'data.read.all';

    if (!token) {
        throw new UnauthorizedError('No token provided.');
    }

    const claims = decodeToken(token); // Assume decodeToken extracts claims from JWT

    if (!claims.scopes || !claims.scopes.includes(requiredScope)) {
        throw new ForbiddenError(`Required scope '${requiredScope}' not granted.`);
    }

    // Proceed with accessing the data
    return fetchData();
}
                

Best Practices

• Principle of Least Privilege: Grant only the minimum permissions necessary for a user or application to perform its intended function.
• Centralize Policy Management: Use a dedicated authorization service or library to manage and enforce policies consistently.
• Regularly Audit Permissions: Periodically review user roles and application permissions to ensure they are still appropriate.
• Securely Store and Transmit Credentials: Never hardcode sensitive credentials or tokens. Use secure storage mechanisms.
• Be Specific with Scopes: Define granular scopes that precisely match the functionality of your application.