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AWS Security Token Service
API Reference (API Version 2011-06-15)

AssumeRoleWithWebIdentity

Returns a set of temporary security credentials for users who have been authenticated in a mobile or web application with a web identity provider, such as Amazon Cognito, Login with Amazon, Facebook, Google, or any OpenID Connect-compatible identity provider.

Note

For mobile applications, we recommend that you use Amazon Cognito. You can use Amazon Cognito with the AWS SDK for iOS and the AWS SDK for Android to uniquely identify a user and supply the user with a consistent identity throughout the lifetime of an application.

To learn more about Amazon Cognito, see Amazon Cognito Overview in the AWS SDK for Android Developer Guide guide and Amazon Cognito Overview in the AWS SDK for iOS Developer Guide.

Calling AssumeRoleWithWebIdentity does not require the use of AWS security credentials. Therefore, you can distribute an application (for example, on mobile devices) that requests temporary security credentials without including long-term AWS credentials in the application, and without deploying server-based proxy services that use long-term AWS credentials. Instead, the identity of the caller is validated by using a token from the web identity provider. For a comparison of AssumeRoleWithWebIdentity with the other APIs that produce temporary credentials, see Requesting Temporary Security Credentials and Comparing the AWS STS APIs in the IAM User Guide.

The temporary security credentials returned by this API consist of an access key ID, a secret access key, and a security token. Applications can use these temporary security credentials to sign calls to AWS service APIs.

The credentials are valid for the duration that you specified when calling AssumeRoleWithWebIdentity, which can be from 900 seconds (15 minutes) to a maximum of 3600 seconds (1 hour). The default is 1 hour.

The temporary security credentials created by AssumeRoleWithWebIdentity can be used to make API calls to any AWS service with the following exception: you cannot call the STS service's GetFederationToken or GetSessionToken APIs.

Optionally, you can pass an IAM access policy to this operation. If you choose not to pass a policy, the temporary security credentials that are returned by the operation have the permissions that are defined in the access policy of the role that is being assumed. If you pass a policy to this operation, the temporary security credentials that are returned by the operation have the permissions that are allowed by both the access policy of the role that is being assumed, and the policy that you pass. This gives you a way to further restrict the permissions for the resulting temporary security credentials. You cannot use the passed policy to grant permissions that are in excess of those allowed by the access policy of the role that is being assumed. For more information, see Permissions for AssumeRole, AssumeRoleWithSAML, and AssumeRoleWithWebIdentity in the IAM User Guide.

Before your application can call AssumeRoleWithWebIdentity, you must have an identity token from a supported identity provider and create a role that the application can assume. The role that your application assumes must trust the identity provider that is associated with the identity token. In other words, the identity provider must be specified in the role's trust policy.

Important

Calling AssumeRoleWithWebIdentity can result in an entry in your AWS CloudTrail logs. The entry includes the Subject of the provided Web Identity Token. We recommend that you avoid using any personally identifiable information (PII) in this field. For example, you could instead use a GUID or a pairwise identifier, as suggested in the OIDC specification.

For more information about how to use web identity federation and the AssumeRoleWithWebIdentity API, see the following resources:

Request Parameters

For information about the parameters that are common to all actions, see Common Parameters.

DurationSeconds

The duration, in seconds, of the role session. The value can range from 900 seconds (15 minutes) to 3600 seconds (1 hour). By default, the value is set to 3600 seconds.

Note

This is separate from the duration of a console session that you might request using the returned credentials. The request to the federation endpoint for a console sign-in token takes a SessionDuration parameter that specifies the maximum length of the console session, separately from the DurationSeconds parameter on this API. For more information, see Creating a URL that Enables Federated Users to Access the AWS Management Console in the IAM User Guide.

Type: Integer

Valid Range: Minimum value of 900. Maximum value of 3600.

Required: No

Policy

An IAM policy in JSON format.

The policy parameter is optional. If you pass a policy, the temporary security credentials that are returned by the operation have the permissions that are allowed by both the access policy of the role that is being assumed, and the policy that you pass. This gives you a way to further restrict the permissions for the resulting temporary security credentials. You cannot use the passed policy to grant permissions that are in excess of those allowed by the access policy of the role that is being assumed. For more information, see Permissions for AssumeRoleWithWebIdentity in the IAM User Guide.

The format for this parameter, as described by its regex pattern, is a string of characters up to 2048 characters in length. The characters can be any ASCII character from the space character to the end of the valid character list (\u0020-\u00FF). It can also include the tab (\u0009), linefeed (\u000A), and carriage return (\u000D) characters.

Note

The policy plain text must be 2048 bytes or shorter. However, an internal conversion compresses it into a packed binary format with a separate limit. The PackedPolicySize response element indicates by percentage how close to the upper size limit the policy is, with 100% equaling the maximum allowed size.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 2048.

Pattern: [\u0009\u000A\u000D\u0020-\u00FF]+

Required: No

ProviderId

The fully qualified host component of the domain name of the identity provider.

Specify this value only for OAuth 2.0 access tokens. Currently www.amazon.com and graph.facebook.com are the only supported identity providers for OAuth 2.0 access tokens. Do not include URL schemes and port numbers.

Do not specify this value for OpenID Connect ID tokens.

Type: String

Length Constraints: Minimum length of 4. Maximum length of 2048.

Required: No

RoleArn

The Amazon Resource Name (ARN) of the role that the caller is assuming.

Type: String

Length Constraints: Minimum length of 20. Maximum length of 2048.

Pattern: [\u0009\u000A\u000D\u0020-\u007E\u0085\u00A0-\uD7FF\uE000-\uFFFD\u10000-\u10FFFF]+

Required: Yes

RoleSessionName

An identifier for the assumed role session. Typically, you pass the name or identifier that is associated with the user who is using your application. That way, the temporary security credentials that your application will use are associated with that user. This session name is included as part of the ARN and assumed role ID in the AssumedRoleUser response element.

The regex used to validate this parameter is a string of characters consisting of upper- and lower-case alphanumeric characters with no spaces. You can also include underscores or any of the following characters: =,.@-

Type: String

Length Constraints: Minimum length of 2. Maximum length of 64.

Pattern: [\w+=,.@-]*

Required: Yes

WebIdentityToken

The OAuth 2.0 access token or OpenID Connect ID token that is provided by the identity provider. Your application must get this token by authenticating the user who is using your application with a web identity provider before the application makes an AssumeRoleWithWebIdentity call.

Type: String

Length Constraints: Minimum length of 4. Maximum length of 2048.

Required: Yes

Response Elements

The following elements are returned by the service.

AssumedRoleUser

The Amazon Resource Name (ARN) and the assumed role ID, which are identifiers that you can use to refer to the resulting temporary security credentials. For example, you can reference these credentials as a principal in a resource-based policy by using the ARN or assumed role ID. The ARN and ID include the RoleSessionName that you specified when you called AssumeRole.

Type: AssumedRoleUser object

Audience

The intended audience (also known as client ID) of the web identity token. This is traditionally the client identifier issued to the application that requested the web identity token.

Type: String

Credentials

The temporary security credentials, which include an access key ID, a secret access key, and a security token.

Note: The size of the security token that STS APIs return is not fixed. We strongly recommend that you make no assumptions about the maximum size. As of this writing, the typical size is less than 4096 bytes, but that can vary. Also, future updates to AWS might require larger sizes.

Type: Credentials object

PackedPolicySize

A percentage value that indicates the size of the policy in packed form. The service rejects any policy with a packed size greater than 100 percent, which means the policy exceeded the allowed space.

Type: Integer

Valid Range: Minimum value of 0.

Provider

The issuing authority of the web identity token presented. For OpenID Connect ID Tokens this contains the value of the iss field. For OAuth 2.0 access tokens, this contains the value of the ProviderId parameter that was passed in the AssumeRoleWithWebIdentity request.

Type: String

SubjectFromWebIdentityToken

The unique user identifier that is returned by the identity provider. This identifier is associated with the WebIdentityToken that was submitted with the AssumeRoleWithWebIdentity call. The identifier is typically unique to the user and the application that acquired the WebIdentityToken (pairwise identifier). For OpenID Connect ID tokens, this field contains the value returned by the identity provider as the token's sub (Subject) claim.

Type: String

Length Constraints: Minimum length of 6. Maximum length of 255.

Errors

For information about the errors that are common to all actions, see Common Errors.

ExpiredToken

The web identity token that was passed is expired or is not valid. Get a new identity token from the identity provider and then retry the request.

HTTP Status Code: 400

IDPCommunicationError

The request could not be fulfilled because the non-AWS identity provider (IDP) that was asked to verify the incoming identity token could not be reached. This is often a transient error caused by network conditions. Retry the request a limited number of times so that you don't exceed the request rate. If the error persists, the non-AWS identity provider might be down or not responding.

HTTP Status Code: 400

IDPRejectedClaim

The identity provider (IdP) reported that authentication failed. This might be because the claim is invalid.

If this error is returned for the AssumeRoleWithWebIdentity operation, it can also mean that the claim has expired or has been explicitly revoked.

HTTP Status Code: 403

InvalidIdentityToken

The web identity token that was passed could not be validated by AWS. Get a new identity token from the identity provider and then retry the request.

HTTP Status Code: 400

MalformedPolicyDocument

The request was rejected because the policy document was malformed. The error message describes the specific error.

HTTP Status Code: 400

PackedPolicyTooLarge

The request was rejected because the policy document was too large. The error message describes how big the policy document is, in packed form, as a percentage of what the API allows.

HTTP Status Code: 400

RegionDisabled

STS is not activated in the requested region for the account that is being asked to generate credentials. The account administrator must use the IAM console to activate STS in that region. For more information, see Activating and Deactivating AWS STS in an AWS Region in the IAM User Guide.

HTTP Status Code: 403

Example

Sample Request

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https://sts.amazonaws.com/ ?Action=AssumeRoleWithWebIdentity &DurationSeconds=3600 &ProviderId=www.amazon.com &RoleSessionName=app1 &RoleArn=arn:aws:iam::123456789012:role/FederatedWebIdentityRole &WebIdentityToken=Atza%7CIQEBLjAsAhRFiXuWpUXuRvQ9PZL3GMFcYevydwIUFAHZwXZXX XXXXXXJnrulxKDHwy87oGKPznh0D6bEQZTSCzyoCtL_8S07pLpr0zMbn6w1lfVZKNTBdDansFB mtGnIsIapjI6xKR02Yc_2bQ8LZbUXSGm6Ry6_BG7PrtLZtj_dfCTj92xNGed-CrKqjG7nPBjNI L016GGvuS5gSvPRUxWES3VYfm1wl7WTI7jn-Pcb6M-buCgHhFOzTQxod27L9CqnOLio7N3gZAG psp6n1-AJBOCJckcyXe2c6uD0srOJeZlKUm2eTDVMf8IehDVI0r1QOnTV6KzzAI3OY87Vd_cVMQ &Version=2011-06-15

Sample Response

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<AssumeRoleWithWebIdentityResponse xmlns="https://sts.amazonaws.com/doc/2011-06-15/"> <AssumeRoleWithWebIdentityResult> <SubjectFromWebIdentityToken>amzn1.account.AF6RHO7KZU5XRVQJGXK6HB56KR2A</SubjectFromWebIdentityToken> <Audience>client.5498841531868486423.1548@apps.example.com</Audience> <AssumedRoleUser> <Arn>arn:aws:sts::123456789012:assumed-role/FederatedWebIdentityRole/app1</Arn> <AssumedRoleId>AROACLKWSDQRAOEXAMPLE:app1</AssumedRoleId> </AssumedRoleUser> <Credentials> <SessionToken>AQoDYXdzEE0a8ANXXXXXXXXNO1ewxE5TijQyp+IEXAMPLE</SessionToken> <SecretAccessKey>wJalrXUtnFEMI/K7MDENG/bPxRfiCYzEXAMPLEKEY</SecretAccessKey> <Expiration>2014-10-24T23:00:23Z</Expiration> <AccessKeyId>AKIAIOSFODNN7EXAMPLE</AccessKeyId> </Credentials> <Provider>www.amazon.com</Provider> </AssumeRoleWithWebIdentityResult> <ResponseMetadata> <RequestId>ad4156e9-bce1-11e2-82e6-6b6efEXAMPLE</RequestId> </ResponseMetadata> </AssumeRoleWithWebIdentityResponse>

See Also

For more information about using this API in one of the language-specific AWS SDKs, see the following: