aws_sts
AWS Security Token Service
AWS Security Token Service (STS) enables you to request temporary, limited-privilege credentials for AWS Identity and Access Management (IAM) users or for users that you authenticate (federated users).
This guide provides descriptions of the STS API. For more information about using this service, see Temporary Security Credentials.Summary
Functions
-
assume_role(Client, Input)
Returns a set of temporary security credentials that you can use to access AWS resources that you might not normally have access to.
- assume_role(Client, Input, Options)
-
assume_role_with_saml(Client, Input)
Returns a set of temporary security credentials for users who have been authenticated via a SAML authentication response.
- assume_role_with_saml(Client, Input, Options)
-
assume_role_with_web_identity(Client, Input)
Returns a set of temporary security credentials for users who have been authenticated in a mobile or web application with a web identity provider.
- assume_role_with_web_identity(Client, Input, Options)
-
decode_authorization_message(Client, Input)
Decodes additional information about the authorization status of a request from an encoded message returned in response to an AWS request.
- decode_authorization_message(Client, Input, Options)
-
get_access_key_info(Client, Input)
Returns the account identifier for the specified access key ID.
- get_access_key_info(Client, Input, Options)
-
get_caller_identity(Client, Input)
Returns details about the IAM user or role whose credentials are used to call the operation.
- get_caller_identity(Client, Input, Options)
-
get_federation_token(Client, Input)
Returns a set of temporary security credentials (consisting of an access key ID, a secret access key, and a security token) for a federated user.
- get_federation_token(Client, Input, Options)
-
get_session_token(Client, Input)
Returns a set of temporary credentials for an AWS account or IAM user.
- get_session_token(Client, Input, Options)
Functions
assume_role(Client, Input)
Returns a set of temporary security credentials that you can use to access AWS resources that you might not normally have access to.
These temporary credentials consist of an access key ID, a secret access
key, and a security token. Typically, you use AssumeRole
within your
account or for cross-account access. For a comparison of AssumeRole
with
other API operations that produce temporary credentials, see Requesting
Temporary Security Credentials and Comparing the AWS STS API operations in
the IAM User Guide.
You cannot use AWS account root user credentials to call AssumeRole
. You
must use credentials for an IAM user or an IAM role to call AssumeRole
.
For cross-account access, imagine that you own multiple accounts and need to access resources in each account. You could create long-term credentials in each account to access those resources. However, managing all those credentials and remembering which one can access which account can be time consuming. Instead, you can create one set of long-term credentials in one account. Then use temporary security credentials to access all the other accounts by assuming roles in those accounts. For more information about roles, see IAM Roles in the IAM User Guide.
Session Duration
By default, the temporary security credentials created by AssumeRole
last for one hour. However, you can use the optional DurationSeconds
parameter to specify the duration of your session. You can provide a value
from 900 seconds (15 minutes) up to the maximum session duration setting
for the role. This setting can have a value from 1 hour to 12 hours. To
learn how to view the maximum value for your role, see View the Maximum
Session Duration Setting for a Role in the IAM User Guide. The maximum
session duration limit applies when you use the AssumeRole*
API
operations or the assume-role*
CLI commands. However the limit does not
apply when you use those operations to create a console URL. For more
information, see Using IAM Roles in the IAM User Guide.
Permissions
The temporary security credentials created by AssumeRole
can be used to
make API calls to any AWS service with the following exception: You cannot
call the AWS STS GetFederationToken
or GetSessionToken
API operations.
(Optional) You can pass inline or managed session policies to this operation. You can pass a single JSON policy document to use as an inline session policy. You can also specify up to 10 managed policies to use as managed session policies. The plain text that you use for both inline and managed session policies can't exceed 2,048 characters. Passing policies to this operation returns new temporary credentials. The resulting session's permissions are the intersection of the role's identity-based policy and the session policies. You can use the role's temporary credentials in subsequent AWS API calls to access resources in the account that owns the role. You cannot use session policies to grant more permissions than those allowed by the identity-based policy of the role that is being assumed. For more information, see Session Policies in the IAM User Guide.
To assume a role from a different account, your AWS account must be trusted by the role. The trust relationship is defined in the role's trust policy when the role is created. That trust policy states which accounts are allowed to delegate that access to users in the account.
A user who wants to access a role in a different account must also have
permissions that are delegated from the user account administrator. The
administrator must attach a policy that allows the user to call
AssumeRole
for the ARN of the role in the other account. If the user is
in the same account as the role, then you can do either of the following:
Attach a policy to the user (identical to the previous user in a different account).
Add the user as a principal directly in the role's trust policy.
In this case, the trust policy acts as an IAM resource-based policy. Users in the same account as the role do not need explicit permission to assume the role. For more information about trust policies and resource-based policies, see IAM Policies in the IAM User Guide.
Tags
(Optional) You can pass tag key-value pairs to your session. These tags are called session tags. For more information about session tags, see Passing Session Tags in STS in the IAM User Guide.
An administrator must grant you the permissions necessary to pass session tags. The administrator can also create granular permissions to allow you to pass only specific session tags. For more information, see Tutorial: Using Tags for Attribute-Based Access Control in the IAM User Guide.
You can set the session tags as transitive. Transitive tags persist during role chaining. For more information, see Chaining Roles with Session Tags in the IAM User Guide.
Using MFA with AssumeRole
(Optional) You can include multi-factor authentication (MFA) information
when you call AssumeRole
. This is useful for cross-account scenarios to
ensure that the user that assumes the role has been authenticated with an
AWS MFA device. In that scenario, the trust policy of the role being
assumed includes a condition that tests for MFA authentication. If the
caller does not include valid MFA information, the request to assume the
role is denied. The condition in a trust policy that tests for MFA
authentication might look like the following example.
"Condition": {"Bool": {"aws:MultiFactorAuthPresent": true}}
For more information, see Configuring MFA-Protected API Access in the IAM User Guide guide.
To use MFA withAssumeRole
, you pass values for the SerialNumber
and
TokenCode
parameters. The SerialNumber
value identifies the user's
hardware or virtual MFA device. The TokenCode
is the time-based one-time
password (TOTP) that the MFA device produces.
assume_role(Client, Input, Options)
assume_role_with_saml(Client, Input)
Returns a set of temporary security credentials for users who have been authenticated via a SAML authentication response.
This operation provides a mechanism for tying an enterprise identity store
or directory to role-based AWS access without user-specific credentials or
configuration. For a comparison of AssumeRoleWithSAML
with the other API
operations that produce temporary credentials, see Requesting Temporary
Security Credentials and Comparing the AWS STS API operations in the IAM
User Guide.
The temporary security credentials returned by this operation 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 services.
Session Duration
By default, the temporary security credentials created by
AssumeRoleWithSAML
last for one hour. However, you can use the optional
DurationSeconds
parameter to specify the duration of your session. Your
role session lasts for the duration that you specify, or until the time
specified in the SAML authentication response's SessionNotOnOrAfter
value, whichever is shorter. You can provide a DurationSeconds
value
from 900 seconds (15 minutes) up to the maximum session duration setting
for the role. This setting can have a value from 1 hour to 12 hours. To
learn how to view the maximum value for your role, see View the Maximum
Session Duration Setting for a Role in the IAM User Guide. The maximum
session duration limit applies when you use the AssumeRole*
API
operations or the assume-role*
CLI commands. However the limit does not
apply when you use those operations to create a console URL. For more
information, see Using IAM Roles in the IAM User Guide.
Permissions
The temporary security credentials created by AssumeRoleWithSAML
can be
used to make API calls to any AWS service with the following exception:
you cannot call the STS GetFederationToken
or GetSessionToken
API
operations.
(Optional) You can pass inline or managed session policies to this operation. You can pass a single JSON policy document to use as an inline session policy. You can also specify up to 10 managed policies to use as managed session policies. The plain text that you use for both inline and managed session policies can't exceed 2,048 characters. Passing policies to this operation returns new temporary credentials. The resulting session's permissions are the intersection of the role's identity-based policy and the session policies. You can use the role's temporary credentials in subsequent AWS API calls to access resources in the account that owns the role. You cannot use session policies to grant more permissions than those allowed by the identity-based policy of the role that is being assumed. For more information, see Session Policies in the IAM User Guide.
Calling AssumeRoleWithSAML
does not require the use of AWS security
credentials. The identity of the caller is validated by using keys in the
metadata document that is uploaded for the SAML provider entity for your
identity provider.
Calling AssumeRoleWithSAML
can result in an entry in your AWS CloudTrail
logs. The entry includes the value in the NameID
element of the SAML
assertion. We recommend that you use a NameIDType
that is not associated
with any personally identifiable information (PII). For example, you could
instead use the persistent identifier
(urn:oasis:names:tc:SAML:2.0:nameid-format:persistent
).
Tags
(Optional) You can configure your IdP to pass attributes into your SAML assertion as session tags. Each session tag consists of a key name and an associated value. For more information about session tags, see Passing Session Tags in STS in the IAM User Guide.
You can pass up to 50 session tags. The plain text session tag keys can’t exceed 128 characters and the values can’t exceed 256 characters. For these and additional limits, see IAM and STS Character Limits in the IAM User Guide.
An AWS conversion compresses the passed session policies and session tags
into a packed binary format that has a separate limit. Your request can
fail for this limit even if your plain text meets the other requirements.
The PackedPolicySize
response element indicates by percentage how close
the policies and tags for your request are to the upper size limit.
You can pass a session tag with the same key as a tag that is attached to the role. When you do, session tags override the role's tags with the same key.
An administrator must grant you the permissions necessary to pass session tags. The administrator can also create granular permissions to allow you to pass only specific session tags. For more information, see Tutorial: Using Tags for Attribute-Based Access Control in the IAM User Guide.
You can set the session tags as transitive. Transitive tags persist during role chaining. For more information, see Chaining Roles with Session Tags in the IAM User Guide.
SAML Configuration
Before your application can call AssumeRoleWithSAML
, you must configure
your SAML identity provider (IdP) to issue the claims required by AWS.
Additionally, you must use AWS Identity and Access Management (IAM) to
create a SAML provider entity in your AWS account that represents your
identity provider. You must also create an IAM role that specifies this
SAML provider in its trust policy.
For more information, see the following resources:
About SAML 2.0-based Federation in the IAM User Guide.
Creating SAML Identity Providers in the IAM User Guide.
Configuring a Relying Party and Claims in the IAM User Guide.
Creating a Role for SAML 2.0 Federation in the IAM User Guide.
assume_role_with_saml(Client, Input, Options)
assume_role_with_web_identity(Client, Input)
Returns a set of temporary security credentials for users who have been authenticated in a mobile or web application with a web identity provider.
Example providers include Amazon Cognito, Login with Amazon, Facebook, Google, or any OpenID Connect-compatible identity provider.
For mobile applications, we recommend that you use Amazon Cognito. You can use Amazon Cognito with the AWS SDK for iOS Developer Guide and the AWS SDK for Android Developer Guide to uniquely identify a user. You can also supply the user with a consistent identity throughout the lifetime of an application.
To learn more about Amazon Cognito, see Amazon Cognito Overview in AWS SDK for Android Developer 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. You also
don't need to deploy 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 API operations that produce
temporary credentials, see Requesting Temporary Security Credentials and
Comparing the AWS STS API operations 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 API operations.
Session Duration
By default, the temporary security credentials created by
AssumeRoleWithWebIdentity
last for one hour. However, you can use the
optional DurationSeconds
parameter to specify the duration of your
session. You can provide a value from 900 seconds (15 minutes) up to the
maximum session duration setting for the role. This setting can have a
value from 1 hour to 12 hours. To learn how to view the maximum value for
your role, see View the Maximum Session Duration Setting for a Role in the
IAM User Guide. The maximum session duration limit applies when you use
the AssumeRole*
API operations or the assume-role*
CLI commands.
However the limit does not apply when you use those operations to create a
console URL. For more information, see Using IAM Roles in the IAM User
Guide.
Permissions
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 GetFederationToken
or
GetSessionToken
API operations.
(Optional) You can pass inline or managed session policies to this operation. You can pass a single JSON policy document to use as an inline session policy. You can also specify up to 10 managed policies to use as managed session policies. The plain text that you use for both inline and managed session policies can't exceed 2,048 characters. Passing policies to this operation returns new temporary credentials. The resulting session's permissions are the intersection of the role's identity-based policy and the session policies. You can use the role's temporary credentials in subsequent AWS API calls to access resources in the account that owns the role. You cannot use session policies to grant more permissions than those allowed by the identity-based policy of the role that is being assumed. For more information, see Session Policies in the IAM User Guide.
Tags
(Optional) You can configure your IdP to pass attributes into your web identity token as session tags. Each session tag consists of a key name and an associated value. For more information about session tags, see Passing Session Tags in STS in the IAM User Guide.
You can pass up to 50 session tags. The plain text session tag keys can’t exceed 128 characters and the values can’t exceed 256 characters. For these and additional limits, see IAM and STS Character Limits in the IAM User Guide.
An AWS conversion compresses the passed session policies and session tags
into a packed binary format that has a separate limit. Your request can
fail for this limit even if your plain text meets the other requirements.
The PackedPolicySize
response element indicates by percentage how close
the policies and tags for your request are to the upper size limit.
You can pass a session tag with the same key as a tag that is attached to the role. When you do, the session tag overrides the role tag with the same key.
An administrator must grant you the permissions necessary to pass session tags. The administrator can also create granular permissions to allow you to pass only specific session tags. For more information, see Tutorial: Using Tags for Attribute-Based Access Control in the IAM User Guide.
You can set the session tags as transitive. Transitive tags persist during role chaining. For more information, see Chaining Roles with Session Tags in the IAM User Guide.
Identities
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.
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:
Using Web Identity Federation API Operations for Mobile Apps and Federation Through a Web-based Identity Provider.
Web Identity Federation Playground. Walk through the process of authenticating through Login with Amazon, Facebook, or Google, getting temporary security credentials, and then using those credentials to make a request to AWS.
AWS SDK for iOS Developer Guide and AWS SDK for Android Developer Guide. These toolkits contain sample apps that show how to invoke the identity providers. The toolkits then show how to use the information from these providers to get and use temporary security credentials.
Web Identity Federation with Mobile Applications. This article discusses web identity federation and shows an example of how to use web identity federation to get access to content in Amazon S3.
assume_role_with_web_identity(Client, Input, Options)
decode_authorization_message(Client, Input)
Decodes additional information about the authorization status of a request from an encoded message returned in response to an AWS request.
For example, if a user is not authorized to perform an operation that he
or she has requested, the request returns a Client.UnauthorizedOperation
response (an HTTP 403 response). Some AWS operations additionally return
an encoded message that can provide details about this authorization
failure.
Only certain AWS operations return an encoded authorization message. The documentation for an individual operation indicates whether that operation returns an encoded message in addition to returning an HTTP code.
The message is encoded because the details of the authorization status can
constitute privileged information that the user who requested the
operation should not see. To decode an authorization status message, a
user must be granted permissions via an IAM policy to request the
DecodeAuthorizationMessage
(sts:DecodeAuthorizationMessage
) action.
The decoded message includes the following type of information:
Whether the request was denied due to an explicit deny or due to the absence of an explicit allow. For more information, see Determining Whether a Request is Allowed or Denied in the IAM User Guide.
The principal who made the request.
The requested action.
The requested resource.
The values of condition keys in the context of the user's request.
decode_authorization_message(Client, Input, Options)
get_access_key_info(Client, Input)
Returns the account identifier for the specified access key ID.
Access keys consist of two parts: an access key ID (for example,
AKIAIOSFODNN7EXAMPLE
) and a secret access key (for example,
wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY
). For more information about
access keys, see Managing Access Keys for IAM Users in the IAM User Guide.
When you pass an access key ID to this operation, it returns the ID of the
AWS account to which the keys belong. Access key IDs beginning with AKIA
are long-term credentials for an IAM user or the AWS account root user.
Access key IDs beginning with ASIA
are temporary credentials that are
created using STS operations. If the account in the response belongs to
you, you can sign in as the root user and review your root user access
keys. Then, you can pull a credentials report to learn which IAM user owns
the keys. To learn who requested the temporary credentials for an ASIA
access key, view the STS events in your CloudTrail logs in the IAM User
Guide.
get_access_key_info(Client, Input, Options)
get_caller_identity(Client, Input)
Returns details about the IAM user or role whose credentials are used to call the operation.
No permissions are required to perform this operation. If an administrator adds a policy to your IAM user or role that explicitly denies access to thests:GetCallerIdentity
action, you can still perform this operation.
Permissions are not required because the same information is returned when
an IAM user or role is denied access. To view an example response, see I
Am Not Authorized to Perform: iam:DeleteVirtualMFADevice in the IAM User
Guide.
get_caller_identity(Client, Input, Options)
get_federation_token(Client, Input)
Returns a set of temporary security credentials (consisting of an access key ID, a secret access key, and a security token) for a federated user.
A typical use is in a proxy application that gets temporary security
credentials on behalf of distributed applications inside a corporate
network. You must call the GetFederationToken
operation using the
long-term security credentials of an IAM user. As a result, this call is
appropriate in contexts where those credentials can be safely stored,
usually in a server-based application. For a comparison of
GetFederationToken
with the other API operations that produce temporary
credentials, see Requesting Temporary Security Credentials and Comparing
the AWS STS API operations in the IAM User Guide.
You can create a mobile-based or browser-based app that can authenticate
users using a web identity provider like Login with Amazon, Facebook,
Google, or an OpenID Connect-compatible identity provider. In this case,
we recommend that you use Amazon Cognito or AssumeRoleWithWebIdentity
.
For more information, see Federation Through a Web-based Identity Provider
in the IAM User Guide.
You can also call GetFederationToken
using the security credentials of
an AWS account root user, but we do not recommend it. Instead, we
recommend that you create an IAM user for the purpose of the proxy
application. Then attach a policy to the IAM user that limits federated
users to only the actions and resources that they need to access. For more
information, see IAM Best Practices in the IAM User Guide.
Session duration
The temporary credentials are valid for the specified duration, from 900 seconds (15 minutes) up to a maximum of 129,600 seconds (36 hours). The default session duration is 43,200 seconds (12 hours). Temporary credentials that are obtained by using AWS account root user credentials have a maximum duration of 3,600 seconds (1 hour).
Permissions
You can use the temporary credentials created by GetFederationToken
in
any AWS service except the following:
You cannot call any IAM operations using the AWS CLI or the AWS API.
You cannot call any STS operations except
GetCallerIdentity
.
You must pass an inline or managed session policy to this operation. You can pass a single JSON policy document to use as an inline session policy. You can also specify up to 10 managed policies to use as managed session policies. The plain text that you use for both inline and managed session policies can't exceed 2,048 characters.
Though the session policy parameters are optional, if you do not pass a
policy, then the resulting federated user session has no permissions. When
you pass session policies, the session permissions are the intersection of
the IAM user policies and the session policies that you pass. This gives
you a way to further restrict the permissions for a federated user. You
cannot use session policies to grant more permissions than those that are
defined in the permissions policy of the IAM user. For more information,
see Session Policies in the IAM User Guide. For information about using
GetFederationToken
to create temporary security credentials, see
GetFederationToken—Federation Through a Custom Identity Broker.
You can use the credentials to access a resource that has a resource-based
policy. If that policy specifically references the federated user session
in the Principal
element of the policy, the session has the permissions
allowed by the policy. These permissions are granted in addition to the
permissions granted by the session policies.
Tags
(Optional) You can pass tag key-value pairs to your session. These are called session tags. For more information about session tags, see Passing Session Tags in STS in the IAM User Guide.
An administrator must grant you the permissions necessary to pass session tags. The administrator can also create granular permissions to allow you to pass only specific session tags. For more information, see Tutorial: Using Tags for Attribute-Based Access Control in the IAM User Guide.
Tag key–value pairs are not case sensitive, but case is preserved. This means that you cannot have separateDepartment
and department
tag
keys. Assume that the user that you are federating has the
Department
=Marketing
tag and you pass the department
=engineering
session tag. Department
and department
are not saved as separate tags,
and the session tag passed in the request takes precedence over the user
tag.
get_federation_token(Client, Input, Options)
get_session_token(Client, Input)
Returns a set of temporary credentials for an AWS account or IAM user.
The credentials consist of an access key ID, a secret access key, and a
security token. Typically, you use GetSessionToken
if you want to use
MFA to protect programmatic calls to specific AWS API operations like
Amazon EC2 StopInstances
. MFA-enabled IAM users would need to call
GetSessionToken
and submit an MFA code that is associated with their MFA
device. Using the temporary security credentials that are returned from
the call, IAM users can then make programmatic calls to API operations
that require MFA authentication. If you do not supply a correct MFA code,
then the API returns an access denied error. For a comparison of
GetSessionToken
with the other API operations that produce temporary
credentials, see Requesting Temporary Security Credentials and Comparing
the AWS STS API operations in the IAM User Guide.
Session Duration
The GetSessionToken
operation must be called by using the long-term AWS
security credentials of the AWS account root user or an IAM user.
Credentials that are created by IAM users are valid for the duration that
you specify. This duration can range from 900 seconds (15 minutes) up to a
maximum of 129,600 seconds (36 hours), with a default of 43,200 seconds
(12 hours). Credentials based on account credentials can range from 900
seconds (15 minutes) up to 3,600 seconds (1 hour), with a default of 1
hour.
Permissions
The temporary security credentials created by GetSessionToken
can be
used to make API calls to any AWS service with the following exceptions:
You cannot call any IAM API operations unless MFA authentication information is included in the request.
You cannot call any STS API except
AssumeRole
orGetCallerIdentity
.
We recommend that you do not call GetSessionToken
with AWS
account root user credentials. Instead, follow our best practices by
creating one or more IAM users, giving them the necessary permissions, and
using IAM users for everyday interaction with AWS.
The credentials that are returned by GetSessionToken
are based on
permissions associated with the user whose credentials were used to call
the operation. If GetSessionToken
is called using AWS account root user
credentials, the temporary credentials have root user permissions.
Similarly, if GetSessionToken
is called using the credentials of an IAM
user, the temporary credentials have the same permissions as the IAM user.
GetSessionToken
to create temporary
credentials, go to Temporary Credentials for Users in Untrusted
Environments in the IAM User Guide.