Amazon Cognito Identity Provider
API Reference (API Version 2016-04-18)

InitiateAuth

Initiates the authentication flow.

Request Syntax

{ "AnalyticsMetadata": { "AnalyticsEndpointId": "string" }, "AuthFlow": "string", "AuthParameters": { "string" : "string" }, "ClientId": "string", "ClientMetadata": { "string" : "string" }, "UserContextData": { "EncodedData": "string" } }

Request Parameters

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

The request accepts the following data in JSON format.

AnalyticsMetadata

The Amazon Pinpoint analytics metadata for collecting metrics for InitiateAuth calls.

Type: AnalyticsMetadataType object

Required: No

AuthFlow

The authentication flow for this call to execute. The API action will depend on this value. For example:

  • REFRESH_TOKEN_AUTH will take in a valid refresh token and return new tokens.

  • USER_SRP_AUTH will take in USERNAME and SRP_A and return the SRP variables to be used for next challenge execution.

  • USER_PASSWORD_AUTH will take in USERNAME and PASSWORD and return the next challenge or tokens.

Valid values include:

  • USER_SRP_AUTH: Authentication flow for the Secure Remote Password (SRP) protocol.

  • REFRESH_TOKEN_AUTH/REFRESH_TOKEN: Authentication flow for refreshing the access token and ID token by supplying a valid refresh token.

  • CUSTOM_AUTH: Custom authentication flow.

  • USER_PASSWORD_AUTH: Non-SRP authentication flow; USERNAME and PASSWORD are passed directly. If a user migration Lambda trigger is set, this flow will invoke the user migration Lambda if the USERNAME is not found in the user pool.

ADMIN_NO_SRP_AUTH is not a valid value.

Type: String

Valid Values: USER_SRP_AUTH | REFRESH_TOKEN_AUTH | REFRESH_TOKEN | CUSTOM_AUTH | ADMIN_NO_SRP_AUTH | USER_PASSWORD_AUTH

Required: Yes

AuthParameters

The authentication parameters. These are inputs corresponding to the AuthFlow that you are invoking. The required values depend on the value of AuthFlow:

  • For USER_SRP_AUTH: USERNAME (required), SRP_A (required), SECRET_HASH (required if the app client is configured with a client secret), DEVICE_KEY

  • For REFRESH_TOKEN_AUTH/REFRESH_TOKEN: REFRESH_TOKEN (required), SECRET_HASH (required if the app client is configured with a client secret), DEVICE_KEY

  • For CUSTOM_AUTH: USERNAME (required), SECRET_HASH (if app client is configured with client secret), DEVICE_KEY

Type: String to string map

Required: No

ClientId

The app client ID.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 128.

Pattern: [\w+]+

Required: Yes

ClientMetadata

A map of custom key-value pairs that you can provide as input for certain custom workflows that this action triggers.

You create custom workflows by assigning AWS Lambda functions to user pool triggers. When you use the InitiateAuth API action, Amazon Cognito invokes the AWS Lambda functions that are specified for various triggers. The ClientMetadata value is passed as input to the functions for only the following triggers:

  • Pre signup

  • Pre authentication

  • User migration

When Amazon Cognito invokes the functions for these triggers, it passes a JSON payload, which the function receives as input. This payload contains a validationData attribute, which provides the data that you assigned to the ClientMetadata parameter in your InitiateAuth request. In your function code in AWS Lambda, you can process the validationData value to enhance your workflow for your specific needs.

When you use the InitiateAuth API action, Amazon Cognito also invokes the functions for the following triggers, but it does not provide the ClientMetadata value as input:

  • Post authentication

  • Custom message

  • Pre token generation

  • Create auth challenge

  • Define auth challenge

  • Verify auth challenge

For more information, see Customizing User Pool Workflows with Lambda Triggers in the Amazon Cognito Developer Guide.

Note

Take the following limitations into consideration when you use the ClientMetadata parameter:

  • Amazon Cognito does not store the ClientMetadata value. This data is available only to AWS Lambda triggers that are assigned to a user pool to support custom workflows. If your user pool configuration does not include triggers, the ClientMetadata parameter serves no purpose.

  • Amazon Cognito does not validate the ClientMetadata value.

  • Amazon Cognito does not encrypt the the ClientMetadata value, so don't use it to provide sensitive information.

Type: String to string map

Required: No

UserContextData

Contextual data such as the user's device fingerprint, IP address, or location used for evaluating the risk of an unexpected event by Amazon Cognito advanced security.

Type: UserContextDataType object

Required: No

Response Syntax

{ "AuthenticationResult": { "AccessToken": "string", "ExpiresIn": number, "IdToken": "string", "NewDeviceMetadata": { "DeviceGroupKey": "string", "DeviceKey": "string" }, "RefreshToken": "string", "TokenType": "string" }, "ChallengeName": "string", "ChallengeParameters": { "string" : "string" }, "Session": "string" }

Response Elements

If the action is successful, the service sends back an HTTP 200 response.

The following data is returned in JSON format by the service.

AuthenticationResult

The result of the authentication response. This is only returned if the caller does not need to pass another challenge. If the caller does need to pass another challenge before it gets tokens, ChallengeName, ChallengeParameters, and Session are returned.

Type: AuthenticationResultType object

ChallengeName

The name of the challenge which you are responding to with this call. This is returned to you in the AdminInitiateAuth response if you need to pass another challenge.

Valid values include the following. Note that all of these challenges require USERNAME and SECRET_HASH (if applicable) in the parameters.

  • SMS_MFA: Next challenge is to supply an SMS_MFA_CODE, delivered via SMS.

  • PASSWORD_VERIFIER: Next challenge is to supply PASSWORD_CLAIM_SIGNATURE, PASSWORD_CLAIM_SECRET_BLOCK, and TIMESTAMP after the client-side SRP calculations.

  • CUSTOM_CHALLENGE: This is returned if your custom authentication flow determines that the user should pass another challenge before tokens are issued.

  • DEVICE_SRP_AUTH: If device tracking was enabled on your user pool and the previous challenges were passed, this challenge is returned so that Amazon Cognito can start tracking this device.

  • DEVICE_PASSWORD_VERIFIER: Similar to PASSWORD_VERIFIER, but for devices only.

  • NEW_PASSWORD_REQUIRED: For users which are required to change their passwords after successful first login. This challenge should be passed with NEW_PASSWORD and any other required attributes.

Type: String

Valid Values: SMS_MFA | SOFTWARE_TOKEN_MFA | SELECT_MFA_TYPE | MFA_SETUP | PASSWORD_VERIFIER | CUSTOM_CHALLENGE | DEVICE_SRP_AUTH | DEVICE_PASSWORD_VERIFIER | ADMIN_NO_SRP_AUTH | NEW_PASSWORD_REQUIRED

ChallengeParameters

The challenge parameters. These are returned to you in the InitiateAuth response if you need to pass another challenge. The responses in this parameter should be used to compute inputs to the next call (RespondToAuthChallenge).

All challenges require USERNAME and SECRET_HASH (if applicable).

Type: String to string map

Session

The session which should be passed both ways in challenge-response calls to the service. If the InitiateAuth or RespondToAuthChallenge API call determines that the caller needs to go through another challenge, they return a session with other challenge parameters. This session should be passed as it is to the next RespondToAuthChallenge API call.

Type: String

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

Errors

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

InternalErrorException

This exception is thrown when Amazon Cognito encounters an internal error.

HTTP Status Code: 500

InvalidLambdaResponseException

This exception is thrown when the Amazon Cognito service encounters an invalid AWS Lambda response.

HTTP Status Code: 400

InvalidParameterException

This exception is thrown when the Amazon Cognito service encounters an invalid parameter.

HTTP Status Code: 400

InvalidSmsRoleAccessPolicyException

This exception is returned when the role provided for SMS configuration does not have permission to publish using Amazon SNS.

HTTP Status Code: 400

InvalidSmsRoleTrustRelationshipException

This exception is thrown when the trust relationship is invalid for the role provided for SMS configuration. This can happen if you do not trust cognito-idp.amazonaws.com or the external ID provided in the role does not match what is provided in the SMS configuration for the user pool.

HTTP Status Code: 400

InvalidUserPoolConfigurationException

This exception is thrown when the user pool configuration is invalid.

HTTP Status Code: 400

NotAuthorizedException

This exception is thrown when a user is not authorized.

HTTP Status Code: 400

PasswordResetRequiredException

This exception is thrown when a password reset is required.

HTTP Status Code: 400

ResourceNotFoundException

This exception is thrown when the Amazon Cognito service cannot find the requested resource.

HTTP Status Code: 400

TooManyRequestsException

This exception is thrown when the user has made too many requests for a given operation.

HTTP Status Code: 400

UnexpectedLambdaException

This exception is thrown when the Amazon Cognito service encounters an unexpected exception with the AWS Lambda service.

HTTP Status Code: 400

UserLambdaValidationException

This exception is thrown when the Amazon Cognito service encounters a user validation exception with the AWS Lambda service.

HTTP Status Code: 400

UserNotConfirmedException

This exception is thrown when a user is not confirmed successfully.

HTTP Status Code: 400

UserNotFoundException

This exception is thrown when a user is not found.

HTTP Status Code: 400

See Also

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