You've built a great backend application and now it's time to add authentication and authorization. But where do you start?
There are many ways to implement authentication and authorization for backend applications. In this article, we'll give you an overview of the most common methods and offer some practical tips for each.
Authentication is the process of verifying that a user is who they claim to be. The most common way to do this is with a username and password.
When a user tries to log in to your application, you'll need to check that their username and password are correct. This can be done with a database of users or with an external service like Active Directory.
If the username and password are correct, you'll need to generate a token that the user can use to access the application. This token should be unique to the user and should be stored securely.
One way to generate a token is to use a JSON Web Token (JWT). JWTs contain information about the user and are signed with a secret. This means that you can be sure that the token has not been tampered with.
To use a JWT, you'll first need to create a secret. This can be done with a tool like openssl:
openssl rand -base64 32
Once you have a secret, you can create a JWT:
jwt.sign({ user_id: 1 }, secret, { expiresIn: '1h' })
This will generate a token that expires in one hour. You can use this token to authenticate the user when they make a request to your application.
To verify the token, you'll need the secret that was used to create it. You can then use this to verify the token:
jwt.verify(token, secret)
If the token is valid, you can be sure that the user is who they claim to be.
Another way to generate a token is to use a tool like Auth0. Auth0 is a service that provides authentication and authorization as a service. This means that you don't have to worry about building your own authentication and authorization system.
With Auth0, you can create a token by signing a user in with their username and password. Auth0 will then generate a token for the user. This token can be used to authenticate the user when they make a request to your application.
To verify the token, you'll need to use the Auth0 service. You can then use the Auth0 service to verify the token and get information about the user:
auth0.verifyToken(token, function(err, user) {
if (err) {
// the token is invalid
} else {
// the token is valid
// you can use the user object to get information about the user
}
})
Auth0 also provides a way to generate tokens for API calls. This means that you can use Auth0 to authenticate and authorize users for your API.
Authorization is the process of determining whether a user has access to a certain resource. For example, you might want to allow a user to read a file, but not write to it. Or you might want to allow a user to delete a record, but not create or update it.
There are two common ways to implement authorization: role-based access control and claim-based access control.
With role-based access control, a user is assigned a role. This role defines what the user is allowed to do. For example, a user might have the role of "admin" which allows them to access all resources. Or a user might have the role of "user" which only allows them to access certain resources.
With claim-based access control, a user is assigned one or more claims. Each claim defines what the user is allowed to do. For example, a user might have the claim of "can_read" which allows them to read a resource. Or a user might have the claim of "can_write" which allows them to write to a resource.
To implement authorization, you'll need to decide which approach to use. We recommend using role-based access control for most applications.
Once you've decided which approach to use, you'll need to implement it.
If you're using role-based access control, you'll need to create a roles table in your database. This table will contain the roles that your users can be assigned. Each role will have a name and a description.
You'll also need to create a users table. This table will contain the users in your system. Each user will have a role_id that corresponds to a role in the roles table.
To authorize a user, you'll need to check their role_id against the roles table. For example, if a user is trying to access a resource that they don't have permission to, you can return an error:
if (user.role_id != 1) {
return res.status(403).send('You do not have permission to access this resource');
}
If you're using claim-based access control, you'll need to create a claims table in your database. This table will contain the claims that your users can be assigned. Each claim will have a name and a description.
You'll also need to create a user_claims table. This table will contain the claims for each user. Each claim will have a user_id that corresponds to a user in the users table.
To authorize a user, you'll need to check their user_claims table. For example, if a user is trying to access a resource that they don't have permission to, you can return an error:
if (!user_claims.includes('can_read')) {
return res.status(403).send('You do not have permission to access this resource');
}
There are many ways to implement authentication and authorization for backend applications. In this article, we've given you an overview of the most common methods and offered some practical tips for each.
We hope this article has been helpful and that you now have a better understanding of how to implement authentication and authorization for your backend application.