Responds to the authentication challenge.


This action might generate an SMS text message. Starting June 1, 2021, US telecom carriers require you to register an origination phone number before you can send SMS messages to US phone numbers. If you use SMS text messages in Amazon Cognito, you must register a phone number with Amazon Pinpoint. Amazon Cognito uses the registered number automatically. Otherwise, Amazon Cognito users who must receive SMS messages might not be able to sign up, activate their accounts, or sign in.

If you have never used SMS text messages with Amazon Cognito or any other Amazon Web Service, Amazon Simple Notification Service might place your account in the SMS sandbox. In sandbox mode , you can send messages only to verified phone numbers. After you test your app while in the sandbox environment, you can move out of the sandbox and into production. For more information, see SMS message settings for Amazon Cognito user pools in the Amazon Cognito Developer Guide .

See also: AWS API Documentation

Request Syntax

response = client.respond_to_auth_challenge(
        'string': 'string'
        'AnalyticsEndpointId': 'string'
        'IpAddress': 'string',
        'EncodedData': 'string'
        'string': 'string'
  • ClientId (string) --


    The app client ID.

  • ChallengeName (string) --


    The challenge name. For more information, see InitiateAuth.

    ADMIN_NO_SRP_AUTH isn't a valid value.
  • Session (string) -- The session that should be passed both ways in challenge-response calls to the service. If InitiateAuth or RespondToAuthChallenge API call determines that the caller must pass another challenge, they return a session with other challenge parameters. This session should be passed as it is to the next RespondToAuthChallenge API call.
  • ChallengeResponses (dict) --

    The challenge responses. These are inputs corresponding to the value of ChallengeName , for example:


    SECRET_HASH (if app client is configured with client secret) applies to all of the inputs that follow (including SOFTWARE_TOKEN_MFA ).



    PASSWORD_VERIFIER requires DEVICE_KEY when you sign in with a remembered device.

    • NEW_PASSWORD_REQUIRED : NEW_PASSWORD , USERNAME , SECRET_HASH (if app client is configured with client secret). To set any required attributes that Amazon Cognito returned as requiredAttributes in the InitiateAuth response, add a userAttributes.attributename parameter. This parameter can also set values for writable attributes that aren't required by your user pool.


    In a NEW_PASSWORD_REQUIRED challenge response, you can't modify a required attribute that already has a value. In RespondToAuthChallenge , set a value for any keys that Amazon Cognito returned in the requiredAttributes parameter, then use the UpdateUserAttributes API operation to modify the value of any additional attributes.

    • SOFTWARE_TOKEN_MFA : USERNAME and SOFTWARE_TOKEN_MFA_CODE are required attributes.
    • DEVICE_PASSWORD_VERIFIER requires everything that PASSWORD_VERIFIER requires, plus DEVICE_KEY .
    • MFA_SETUP requires USERNAME , plus you must use the session value returned by VerifySoftwareToken in the Session parameter.
    • (string) --
      • (string) --
  • AnalyticsMetadata (dict) --

    The Amazon Pinpoint analytics metadata that contributes to your metrics for RespondToAuthChallenge calls.

    • AnalyticsEndpointId (string) --

      The endpoint ID.

  • UserContextData (dict) --

    Contextual data about your user session, such as the device fingerprint, IP address, or location. Amazon Cognito advanced security evaluates the risk of an authentication event based on the context that your app generates and passes to Amazon Cognito when it makes API requests.

    • IpAddress (string) --

      The source IP address of your user's device.

    • EncodedData (string) --

      Encoded device-fingerprint details that your app collected with the Amazon Cognito context data collection library. For more information, see Adding user device and session data to API requests.

  • ClientMetadata (dict) --

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

    You create custom workflows by assigning Lambda functions to user pool triggers. When you use the RespondToAuthChallenge API action, Amazon Cognito invokes any functions that are assigned to the following triggers: post authentication , pre token generation , define auth challenge , create auth challenge , and verify auth challenge . When Amazon Cognito invokes any of these functions, it passes a JSON payload, which the function receives as input. This payload contains a clientMetadata attribute, which provides the data that you assigned to the ClientMetadata parameter in your RespondToAuthChallenge request. In your function code in Lambda, you can process the clientMetadata value to enhance your workflow for your specific needs.

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


    When you use the ClientMetadata parameter, remember that Amazon Cognito won't do the following:

    • Store the ClientMetadata value. This data is available only to Lambda triggers that are assigned to a user pool to support custom workflows. If your user pool configuration doesn't include triggers, the ClientMetadata parameter serves no purpose.
    • Validate the ClientMetadata value.
    • Encrypt the ClientMetadata value. Don't use Amazon Cognito to provide sensitive information.
    • (string) --
      • (string) --
Return type



Response Syntax

    'Session': 'string',
    'ChallengeParameters': {
        'string': 'string'
    'AuthenticationResult': {
        'AccessToken': 'string',
        'ExpiresIn': 123,
        'TokenType': 'string',
        'RefreshToken': 'string',
        'IdToken': 'string',
        'NewDeviceMetadata': {
            'DeviceKey': 'string',
            'DeviceGroupKey': 'string'

Response Structure

  • (dict) --

    The response to respond to the authentication challenge.

    • ChallengeName (string) --

      The challenge name. For more information, see InitiateAuth.

    • Session (string) --

      The session that should be passed both ways in challenge-response calls to the service. If the caller must pass another challenge, they return a session with other challenge parameters. This session should be passed as it is to the next RespondToAuthChallenge API call.

    • ChallengeParameters (dict) --

      The challenge parameters. For more information, see InitiateAuth.

      • (string) --
        • (string) --
    • AuthenticationResult (dict) --

      The result returned by the server in response to the request to respond to the authentication challenge.

      • AccessToken (string) --

        A valid access token that Amazon Cognito issued to the user who you want to authenticate.

      • ExpiresIn (integer) --

        The expiration period of the authentication result in seconds.

      • TokenType (string) --

        The token type.

      • RefreshToken (string) --

        The refresh token.

      • IdToken (string) --

        The ID token.

      • NewDeviceMetadata (dict) --

        The new device metadata from an authentication result.

        • DeviceKey (string) --

          The device key.

        • DeviceGroupKey (string) --

          The device group key.


  • CognitoIdentityProvider.Client.exceptions.ResourceNotFoundException
  • CognitoIdentityProvider.Client.exceptions.InvalidParameterException
  • CognitoIdentityProvider.Client.exceptions.NotAuthorizedException
  • CognitoIdentityProvider.Client.exceptions.CodeMismatchException
  • CognitoIdentityProvider.Client.exceptions.ExpiredCodeException
  • CognitoIdentityProvider.Client.exceptions.UnexpectedLambdaException
  • CognitoIdentityProvider.Client.exceptions.UserLambdaValidationException
  • CognitoIdentityProvider.Client.exceptions.InvalidPasswordException
  • CognitoIdentityProvider.Client.exceptions.InvalidLambdaResponseException
  • CognitoIdentityProvider.Client.exceptions.TooManyRequestsException
  • CognitoIdentityProvider.Client.exceptions.InvalidUserPoolConfigurationException
  • CognitoIdentityProvider.Client.exceptions.MFAMethodNotFoundException
  • CognitoIdentityProvider.Client.exceptions.PasswordResetRequiredException
  • CognitoIdentityProvider.Client.exceptions.UserNotFoundException
  • CognitoIdentityProvider.Client.exceptions.UserNotConfirmedException
  • CognitoIdentityProvider.Client.exceptions.InvalidSmsRoleAccessPolicyException
  • CognitoIdentityProvider.Client.exceptions.InvalidSmsRoleTrustRelationshipException
  • CognitoIdentityProvider.Client.exceptions.AliasExistsException
  • CognitoIdentityProvider.Client.exceptions.InternalErrorException
  • CognitoIdentityProvider.Client.exceptions.SoftwareTokenMFANotFoundException
  • CognitoIdentityProvider.Client.exceptions.ForbiddenException