# How Amazon Comprehend works with IAM
<a name="security_iam_service-with-iam"></a>

Before you use IAM to manage access to Amazon Comprehend, learn what IAM features are available to use with Amazon Comprehend.






**IAM features you can use with Amazon Comprehend**  

| IAM feature | Amazon Comprehend support | 
| --- | --- | 
|  [Identity-based policies](#security_iam_service-with-iam-id-based-policies)  |   Yes  | 
|  [Resource-based policies](#security_iam_service-with-iam-resource-based-policies)  |   Yes  | 
|  [Policy actions](#security_iam_service-with-iam-id-based-policies-actions)  |   Yes  | 
|  [Policy resources](#security_iam_service-with-iam-id-based-policies-resources)  |   Yes  | 
|  [Policy condition keys (service-specific)](#security_iam_service-with-iam-id-based-policies-conditionkeys)  |   Yes  | 
|  [ACLs](#security_iam_service-with-iam-acls)  |   No   | 
|  [ABAC (tags in policies)](#security_iam_service-with-iam-tags)  |   Partial  | 
|  [Temporary credentials](#security_iam_service-with-iam-roles-tempcreds)  |   Yes  | 
|  [Forward access sessions (FAS)](#security_iam_service-with-iam-principal-permissions)  |   Yes  | 
|  [Service roles](#security_iam_service-with-iam-roles-service)  |   Yes  | 
|  [Service-linked roles](#security_iam_service-with-iam-roles-service-linked)  |   No   | 

To get a high-level view of how Amazon Comprehend and other AWS services work with most IAM features, see [AWS services that work with IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_aws-services-that-work-with-iam.html) in the *IAM User Guide*.

## Identity-based policies for Amazon Comprehend
<a name="security_iam_service-with-iam-id-based-policies"></a>

**Supports identity-based policies:** Yes

Identity-based policies are JSON permissions policy documents that you can attach to an identity, such as an IAM user, group of users, or role. These policies control what actions users and roles can perform, on which resources, and under what conditions. To learn how to create an identity-based policy, see [Define custom IAM permissions with customer managed policies](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies_create.html) in the *IAM User Guide*.

With IAM identity-based policies, you can specify allowed or denied actions and resources as well as the conditions under which actions are allowed or denied. To learn about all of the elements that you can use in a JSON policy, see [IAM JSON policy elements reference](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements.html) in the *IAM User Guide*.

### Identity-based policy examples for Amazon Comprehend
<a name="security_iam_service-with-iam-id-based-policies-examples"></a>



To view examples of Amazon Comprehend identity-based policies, see [Identity-based policy examples for Amazon Comprehend](security_iam_id-based-policy-examples.md).

## Resource-based policies within Amazon Comprehend
<a name="security_iam_service-with-iam-resource-based-policies"></a>

**Supports resource-based policies:** Yes

Resource-based policies are JSON policy documents that you attach to a resource. Examples of resource-based policies are IAM *role trust policies* and Amazon S3 *bucket policies*. In services that support resource-based policies, service administrators can use them to control access to a specific resource. For the resource where the policy is attached, the policy defines what actions a specified principal can perform on that resource and under what conditions. You must [specify a principal](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements_principal.html) in a resource-based policy. Principals can include accounts, users, roles, federated users, or AWS services.

To enable cross-account access, you can specify an entire account or IAM entities in another account as the principal in a resource-based policy. For more information, see [Cross account resource access in IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies-cross-account-resource-access.html) in the *IAM User Guide*.

The Amazon Comprehend service supports only one type of resource-based policy (a *custom model policy*), which is attached to a custom model. This policy defines other accounts that can use the custom model.

To learn how to attach a resource-based policy to a custom model, see [Resource-based policies for custom models](custom-copy-sharing.md#custom-copy-sharing-example-policy).

## Policy actions for Amazon Comprehend
<a name="security_iam_service-with-iam-id-based-policies-actions"></a>

**Supports policy actions:** Yes

Administrators can use AWS JSON policies to specify who has access to what. That is, which **principal** can perform **actions** on what **resources**, and under what **conditions**.

The `Action` element of a JSON policy describes the actions that you can use to allow or deny access in a policy. Include actions in a policy to grant permissions to perform the associated operation.



To see a list of Amazon Comprehend actions, see [Actions defined by Amazon Comprehend](https://docs.aws.amazon.com/service-authorization/latest/reference/list_amazoncomprehend.html#amazoncomprehend-actions-as-permissions) in the *Service Authorization Reference*.

Policy actions in Amazon Comprehend use the following prefix before the action:

```
comprehend
```

To specify multiple actions in a single statement, separate them with commas.

```
"Action": [
      "comprehend:DetectSentiment",
      "comprehend:ClassifyDocument"
         ]
```





You can specify multiple actions using wildcards (\$1). For example, to specify all actions that begin with the word `Describe`, include the following action:

```
"Action": "comprehend:Describe*"
```

Don't use wildcards to specify all of the actions for a service. Use the best practice of granting least privilege when you specify the permissions in a policy.

To view examples of Amazon Comprehend identity-based policies, see [Identity-based policy examples for Amazon Comprehend](security_iam_id-based-policy-examples.md).

## Policy resources for Amazon Comprehend
<a name="security_iam_service-with-iam-id-based-policies-resources"></a>

**Supports policy resources:** Yes

Administrators can use AWS JSON policies to specify who has access to what. That is, which **principal** can perform **actions** on what **resources**, and under what **conditions**.

The `Resource` JSON policy element specifies the object or objects to which the action applies. As a best practice, specify a resource using its [Amazon Resource Name (ARN)](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference-arns.html). For actions that don't support resource-level permissions, use a wildcard (\$1) to indicate that the statement applies to all resources.

```
"Resource": "*"
```

To see a list of Amazon Comprehend resource types and their ARNs, see [Resources defined by Amazon Comprehend](https://docs.aws.amazon.com/service-authorization/latest/reference/list_amazoncomprehend.html#amazoncomprehend-resources-for-iam-policies) in the *Service Authorization Reference*. To learn with which actions you can specify the ARN of each resource, see [Actions defined by Amazon Comprehend](https://docs.aws.amazon.com/service-authorization/latest/reference/list_amazoncomprehend.html#amazoncomprehend-actions-as-permissions).





## Policy condition keys for Amazon Comprehend
<a name="security_iam_service-with-iam-id-based-policies-conditionkeys"></a>

**Supports service-specific policy condition keys:** Yes

Administrators can use AWS JSON policies to specify who has access to what. That is, which **principal** can perform **actions** on what **resources**, and under what **conditions**.

The `Condition` element specifies when statements execute based on defined criteria. You can create conditional expressions that use [condition operators](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements_condition_operators.html), such as equals or less than, to match the condition in the policy with values in the request. To see all AWS global condition keys, see [AWS global condition context keys](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_condition-keys.html) in the *IAM User Guide*.

To see a list of Amazon Comprehend condition keys, see [Condition keys for Amazon Comprehend](https://docs.aws.amazon.com/service-authorization/latest/reference/list_amazoncomprehend.html#amazoncomprehend-policy-keys) in the *Service Authorization Reference*. To learn with which actions and resources you can use a condition key, see [Actions defined by Amazon Comprehend](https://docs.aws.amazon.com/service-authorization/latest/reference/list_amazoncomprehend.html#amazoncomprehend-actions-as-permissions).

To view examples of Amazon Comprehend identity-based policies, see [Identity-based policy examples for Amazon Comprehend](security_iam_id-based-policy-examples.md).

## ACLs in Amazon Comprehend
<a name="security_iam_service-with-iam-acls"></a>

**Supports ACLs:** No 

Access control lists (ACLs) control which principals (account members, users, or roles) have permissions to access a resource. ACLs are similar to resource-based policies, although they do not use the JSON policy document format.

## ABAC with Amazon Comprehend
<a name="security_iam_service-with-iam-tags"></a>

**Supports ABAC (tags in policies):** Partial

Attribute-based access control (ABAC) is an authorization strategy that defines permissions based on attributes called tags. You can attach tags to IAM entities and AWS resources, then design ABAC policies to allow operations when the principal's tag matches the tag on the resource.

To control access based on tags, you provide tag information in the [condition element](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_policies_elements_condition.html) of a policy using the `aws:ResourceTag/key-name`, `aws:RequestTag/key-name`, or `aws:TagKeys` condition keys.

If a service supports all three condition keys for every resource type, then the value is **Yes** for the service. If a service supports all three condition keys for only some resource types, then the value is **Partial**.

For more information about ABAC, see [Define permissions with ABAC authorization](https://docs.aws.amazon.com/IAM/latest/UserGuide/introduction_attribute-based-access-control.html) in the *IAM User Guide*. To view a tutorial with steps for setting up ABAC, see [Use attribute-based access control (ABAC)](https://docs.aws.amazon.com/IAM/latest/UserGuide/tutorial_attribute-based-access-control.html) in the *IAM User Guide*.

For more information about tagging Amazon Comprehend resources, see [Tagging your resources](tagging.md).

## Using temporary credentials with Amazon Comprehend
<a name="security_iam_service-with-iam-roles-tempcreds"></a>

**Supports temporary credentials:** Yes

Temporary credentials provide short-term access to AWS resources and are automatically created when you use federation or switch roles. AWS recommends that you dynamically generate temporary credentials instead of using long-term access keys. For more information, see [Temporary security credentials in IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_credentials_temp.html) and [AWS services that work with IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_aws-services-that-work-with-iam.html) in the *IAM User Guide*.

## Forward access sessions for Amazon Comprehend
<a name="security_iam_service-with-iam-principal-permissions"></a>

**Supports forward access sessions (FAS):** Yes

 Forward access sessions (FAS) use the permissions of the principal calling an AWS service, combined with the requesting AWS service to make requests to downstream services. For policy details when making FAS requests, see [Forward access sessions](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_forward_access_sessions.html). 

## Service roles for Amazon Comprehend
<a name="security_iam_service-with-iam-roles-service"></a>

**Supports service roles:** Yes

 A service role is an [IAM role](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles.html) that a service assumes to perform actions on your behalf. An IAM administrator can create, modify, and delete a service role from within IAM. For more information, see [Create a role to delegate permissions to an AWS service](https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_create_for-service.html) in the *IAM User Guide*. 

**Warning**  
Changing the permissions for a service role might break Amazon Comprehend functionality. Edit service roles only when Amazon Comprehend provides guidance to do so.

To use the Amazon Comprehend asynchronous operations, you must grant Amazon Comprehend access to the Amazon S3 bucket that contains your document collection. You do this by creating a data access role in your account with a trust policy to trust the Amazon Comprehend service principal.

For a policy example, see [Role-based permissions required for asynchronous operations](security_iam_id-based-policy-examples.md#auth-role-permissions)

## Service-linked roles for Amazon Comprehend
<a name="security_iam_service-with-iam-roles-service-linked"></a>

**Supports service-linked roles:** No 

 A service-linked role is a type of service role that is linked to an AWS service. The service can assume the role to perform an action on your behalf. Service-linked roles appear in your AWS account and are owned by the service. An IAM administrator can view, but not edit the permissions for service-linked roles. 

For details about creating or managing service-linked roles, see [AWS services that work with IAM](https://docs.aws.amazon.com/IAM/latest/UserGuide/reference_aws-services-that-work-with-iam.html). Find a service in the table that includes a `Yes` in the **Service-linked role** column. Choose the **Yes** link to view the service-linked role documentation for that service.