What is the process of establishing the identity of user or service that wants to access a resource?

Before you create users, you should understand how IAM works. IAM provides the infrastructure necessary to control authentication and authorization for your account. The IAM infrastructure includes the following elements:

Terms

Learn more about IAM terms.

IAM Resources

The user, group, role, policy, and identity provider objects that are stored in IAM. As with other AWS services, you can add, edit, and remove resources from IAM.

The IAM resource objects that are used to identify and group. You can attach a policy to an IAM identity. These include users, groups, and roles.

The IAM resource objects that AWS uses for authentication. These include IAM users and roles.

A person or application that uses the AWS account root user, an IAM user, or an IAM role to sign in and make requests to AWS. Principals include federated users and assumed roles.

Principal

A principal is a person or application that can make a request for an action or operation on an AWS resource. The principal is authenticated as the AWS account root user or an IAM entity to make requests to AWS. As a best practice, do not use your root user credentials for your daily work. Instead, create IAM entities (users and roles). You can also support federated users or programmatic access to allow an application to access your AWS account.

Request

When a principal tries to use the AWS Management Console, the AWS API, or the AWS CLI, that principal sends a request to AWS. The request includes the following information:

• Actions or operations – The actions or operations that the principal wants to perform. This can be an action in the AWS Management Console, or an operation in the AWS CLI or AWS API.

• Resources – The AWS resource object upon which the actions or operations are performed.

• Principal – The person or application that used an entity (user or role) to send the request. Information about the principal includes the policies that are associated with the entity that the principal used to sign in.

• Environment data – Information about the IP address, user agent, SSL enabled status, or the time of day.

• Resource data – Data related to the resource that is being requested. This can include information such as a DynamoDB table name or a tag on an Amazon EC2 instance.

AWS gathers the request information into a request context, which is used to evaluate and authorize the request.

Authentication

A principal must be authenticated (signed in to AWS) using their credentials to send a request to AWS. Some services, such as Amazon S3 and AWS STS, allow a few requests from anonymous users. However, they are the exception to the rule.

To authenticate from the console as a root user, you must sign in with your email address and password. As an IAM user, provide your account ID or alias, and then your user name and password. To authenticate from the API or AWS CLI, you must provide your access key and secret key. You might also be required to provide additional security information. For example, AWS recommends that you use multi-factor authentication (MFA) to increase the security of your account. To learn more about the IAM entities that AWS can authenticate, see IAM users and IAM roles.

You must also be authorized (allowed) to complete your request. During authorization, AWS uses values from the request context to check for policies that apply to the request. It then uses the policies to determine whether to allow or deny the request. Most policies are stored in AWS as JSON documents and specify the permissions for principal entities. There are several types of policies that can affect whether a request is authorized. To provide your users with permissions to access the AWS resources in their own account, you need only identity-based policies. Resource-based policies are popular for granting cross-account access. The other policy types are advanced features and should be used carefully.

AWS checks each policy that applies to the context of your request. If a single permissions policy includes a denied action, AWS denies the entire request and stops evaluating. This is called an explicit deny. Because requests are denied by default, AWS authorizes your request only if every part of your request is allowed by the applicable permissions policies. The evaluation logic for a request within a single account follows these general rules:

• By default, all requests are denied. (In general, requests made using the AWS account root user credentials for resources in the account are always allowed.)

• An explicit allow in any permissions policy (identity-based or resource-based) overrides this default.

• The existence of an Organizations SCP, IAM permissions boundary, or a session policy overrides the allow. If one or more of these policy types exists, they must all allow the request. Otherwise, it is implicitly denied.

• An explicit deny in any policy overrides any allows.

To learn more about how all types of policies are evaluated, see Policy evaluation logic. If you need to make a request in a different account, a policy in the other account must allow you to access the resource and the IAM entity that you use to make the request must have an identity-based policy that allows the request.

Actions or operations

After your request has been authenticated and authorized, AWS approves the actions or operations in your request. Operations are defined by a service, and include things that you can do to a resource, such as viewing, creating, editing, and deleting that resource. For example, IAM supports approximately 40 actions for a user resource, including the following actions:

• CreateUser

• DeleteUser

• GetUser

• UpdateUser

To allow a principal to perform an operation, you must include the necessary actions in a policy that applies to the principal or the affected resource. To see a list of actions, resource types, and condition keys supported by each service, see Actions, Resources, and Condition Keys for AWS Services.

Resources

After AWS approves the operations in your request, they can be performed on the related resources within your account. A resource is an object that exists within a service. Examples include an Amazon EC2 instance, an IAM user, and an Amazon S3 bucket. The service defines a set of actions that can be performed on each resource. If you create a request to perform an unrelated action on a resource, that request is denied. For example, if you request to delete an IAM role but provide an IAM group resource, the request fails. To see AWS service tables that identify which resources are affected by an action, see Actions, Resources, and Condition Keys for AWS Services.

What's the difference between authentication and authorization? Authentication confirms that users are who they say they are. Authorization gives those users permission to access a resource.

While authentication and authorization might sound similar, they are distinct security processes in the world of identity and access management (IAM).

What Is Authentication?

Authentication is the act of validating that users are whom they claim to be. This is the first step in any security process. 

Complete an authentication process with:

• Passwords. Usernames and passwords are the most common authentication factors. If a user enters the correct data, the system assumes the identity is valid and grants access.
• One-time pins. Grant access for only one session or transaction.
• Authentication apps. Generate security codes via an outside party that grants access.
• Biometrics. A user presents a fingerprint or eye scan to gain access to the system. 

In some instances, systems require the successful verification of more than one factor before granting access. This multi-factor authentication (MFA) requirement is often deployed to increase security beyond what passwords alone can provide.

What Is Authorization?

Authorization in system security is the process of giving the user permission to access a specific resource or function. This term is often used interchangeably with access control or client privilege.

Giving someone permission to download a particular file on a server or providing individual users with administrative access to an application are good examples of authorization.

In secure environments, authorization must always follow authentication. Users should first prove that their identities are genuine before an organization’s administrators grant them access to the requested resources.

Authentication vs. Authorization

Despite the similar-sounding terms, authentication and authorization are separate steps in the login process. Understanding the difference between the two is key to successfully implementing an IAM solution.

Let's use an analogy to outline the differences.

Consider a person walking up to a locked door to provide care to a pet while the family is away on vacation. That person needs:

• Authentication, in the form of a key. The lock on the door only grants access to someone with the correct key in much the same way that a system only grants access to users who have the correct credentials.
• Authorization, in the form of permissions. Once inside, the person has the authorization to access the kitchen and open the cupboard that holds the pet food. The person may not have permission to go into the bedroom for a quick nap. 

Authentication and authorization work together in this example. A pet sitter has the right to enter the house (authentication), and once there, they have access to certain areas (authorization).

Systems implement these concepts in the same way, so it’s crucial that IAM administrators understand how to utilize both:

• Authentication. Let every staff member access your workplace systems if they provide the right credentials in response to your chosen authentication requirements.
• Authorization. Grant permission to department-specific files, and reserve access to confidential data, such as financial information, as needed. Ensure that employees have access to the files they need to do their jobs. 

Understand the difference between authentication and authorization, and implement IAM solutions that have strong support for both. You will protect your organization against data breaches and enable your workforce to be more productive.

Granting Permissions with Okta

Okta Lifecycle Management gives you an at-a-glance view of user permissions, meaning you can easily grant and revoke access to your systems and tools as needed. Meanwhile, Okta Adaptive MFA lets you safeguard your infrastructure behind your choice of authentication factors. 

For example, make production orders accessible only to certain users who may then have to authenticate using both their company credentials and voice recognition. 

The opportunities to streamline IAM in your organization are endless. Find out how Okta can keep you, your employees, and your enterprise safe.