CognitoIdentityProvider / Client / initiate_auth

initiate_auth#

CognitoIdentityProvider.Client.initiate_auth(**kwargs)#

Initiates sign-in for a user in the Amazon Cognito user directory. You can’t sign in a user with a federated IdP with InitiateAuth. For more information, see Adding user pool sign-in through a third party.

Note

Amazon Cognito doesn’t evaluate Identity and Access Management (IAM) policies in requests for this API operation. For this operation, you can’t use IAM credentials to authorize requests, and you can’t grant IAM permissions in policies. For more information about authorization models in Amazon Cognito, see Using the Amazon Cognito user pools API and user pool endpoints.

Note

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 Services 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.

Request Syntax

response = client.initiate_auth(
    AuthFlow='USER_SRP_AUTH'|'REFRESH_TOKEN_AUTH'|'REFRESH_TOKEN'|'CUSTOM_AUTH'|'ADMIN_NO_SRP_AUTH'|'USER_PASSWORD_AUTH'|'ADMIN_USER_PASSWORD_AUTH'|'USER_AUTH',
    AuthParameters={
        'string': 'string'
    },
    ClientMetadata={
        'string': 'string'
    },
    ClientId='string',
    AnalyticsMetadata={
        'AnalyticsEndpointId': 'string'
    },
    UserContextData={
        'IpAddress': 'string',
        'EncodedData': 'string'
    },
    Session='string'
)

Parameters:

AuthFlow (string) –
[REQUIRED]

The authentication flow that you want to initiate. Each AuthFlow has linked AuthParameters that you must submit. The following are some example flows and their parameters.
- USER_AUTH: Request a preferred authentication type or review available authentication types. From the offered authentication types, select one in a challenge response and then authenticate with that method in an additional challenge response.
- REFRESH_TOKEN_AUTH: Receive new ID and access tokens when you pass a REFRESH_TOKEN parameter with a valid refresh token as the value.
- USER_SRP_AUTH: Receive secure remote password (SRP) variables for the next challenge, PASSWORD_VERIFIER, when you pass USERNAME and SRP_A parameters.
- USER_PASSWORD_AUTH: Receive new tokens or the next challenge, for example SOFTWARE_TOKEN_MFA, when you pass USERNAME and PASSWORD parameters.
All flows

USER_AUTH

The entry point for sign-in with passwords, one-time passwords, and WebAuthN authenticators.

USER_SRP_AUTH

Username-password authentication with the Secure Remote Password (SRP) protocol. For more information, see Use SRP password verification in custom authentication flow.

REFRESH_TOKEN_AUTH and REFRESH_TOKEN

Provide a valid refresh token and receive new ID and access tokens. For more information, see Using the refresh token.

CUSTOM_AUTH

Custom authentication with Lambda triggers. For more information, see Custom authentication challenge Lambda triggers.

USER_PASSWORD_AUTH

Username-password authentication with the password sent directly in the request. For more information, see Admin authentication flow.

ADMIN_USER_PASSWORD_AUTH is a flow type of AdminInitiateAuth and isn’t valid for InitiateAuth. ADMIN_NO_SRP_AUTH is a legacy server-side username-password flow and isn’t valid for InitiateAuth.
AuthParameters (dict) –
The authentication parameters. These are inputs corresponding to the AuthFlow that you’re invoking. The required values depend on the value of AuthFlow:
- For USER_AUTH: USERNAME (required), PREFERRED_CHALLENGE. If you don’t provide a value for PREFERRED_CHALLENGE, Amazon Cognito responds with the AvailableChallenges parameter that specifies the available sign-in methods.
- 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 USER_PASSWORD_AUTH: USERNAME (required), PASSWORD (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. To start the authentication flow with password verification, include ChallengeName: SRP_A and SRP_A: (The SRP_A Value).
For more information about SECRET_HASH, see Computing secret hash values. For information about DEVICE_KEY, see Working with user devices in your user pool.
- (string) –
  - (string) –
ClientMetadata (dict) –
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 Lambda functions to user pool triggers. When you use the InitiateAuth API action, Amazon Cognito invokes the 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 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 doesn’t provide the ClientMetadata value as input:
- Post authentication
- Custom message
- Pre token generation
- Create auth challenge
- Define auth challenge
- Custom email sender
- Custom SMS sender
For more information, see Customizing user pool Workflows with Lambda Triggers in the Amazon Cognito Developer Guide.
Note
When you use the ClientMetadata parameter, note 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 send sensitive information in this parameter.
- (string) –
  - (string) –
ClientId (string) –
[REQUIRED]

The app client ID.
AnalyticsMetadata (dict) –
The Amazon Pinpoint analytics metadata that contributes to your metrics for InitiateAuth calls.
- AnalyticsEndpointId (string) –
  
  The endpoint ID. Information that you want to pass to Amazon Pinpoint about where to send notifications.
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.

For more information, see Collecting data for threat protection in applications.
- 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.
Session (string) – The optional session ID from a ConfirmSignUp API request. You can sign in a user directly from the sign-up process with the USER_AUTH authentication flow.

Return type:

dict

Returns:

Response Syntax

{
    'ChallengeName': 'SMS_MFA'|'EMAIL_OTP'|'SOFTWARE_TOKEN_MFA'|'SELECT_MFA_TYPE'|'MFA_SETUP'|'PASSWORD_VERIFIER'|'CUSTOM_CHALLENGE'|'SELECT_CHALLENGE'|'DEVICE_SRP_AUTH'|'DEVICE_PASSWORD_VERIFIER'|'ADMIN_NO_SRP_AUTH'|'NEW_PASSWORD_REQUIRED'|'SMS_OTP'|'PASSWORD'|'WEB_AUTHN'|'PASSWORD_SRP',
    'Session': 'string',
    'ChallengeParameters': {
        'string': 'string'
    },
    'AuthenticationResult': {
        'AccessToken': 'string',
        'ExpiresIn': 123,
        'TokenType': 'string',
        'RefreshToken': 'string',
        'IdToken': 'string',
        'NewDeviceMetadata': {
            'DeviceKey': 'string',
            'DeviceGroupKey': 'string'
        }
    },
    'AvailableChallenges': [
        'SMS_MFA'|'EMAIL_OTP'|'SOFTWARE_TOKEN_MFA'|'SELECT_MFA_TYPE'|'MFA_SETUP'|'PASSWORD_VERIFIER'|'CUSTOM_CHALLENGE'|'SELECT_CHALLENGE'|'DEVICE_SRP_AUTH'|'DEVICE_PASSWORD_VERIFIER'|'ADMIN_NO_SRP_AUTH'|'NEW_PASSWORD_REQUIRED'|'SMS_OTP'|'PASSWORD'|'WEB_AUTHN'|'PASSWORD_SRP',
    ]
}

Response Structure

(dict) –

Initiates the authentication response.
- ChallengeName (string) –
  
  The name of the challenge that you’re responding to with this call. This name is returned in the InitiateAuth response if you must pass another challenge.
  
  Valid values include the following:
  
  Note
  All of the following challenges require USERNAME and SECRET_HASH (if applicable) in the parameters.
  - WEB_AUTHN: Respond to the challenge with the results of a successful authentication with a passkey, or webauthN, factor. These are typically biometric devices or security keys.
  - PASSWORD: Respond with USER_PASSWORD_AUTH parameters: USERNAME (required), PASSWORD (required), SECRET_HASH (required if the app client is configured with a client secret), DEVICE_KEY.
  - PASSWORD_SRP: Respond with USER_SRP_AUTH parameters: USERNAME (required), SRP_A (required), SECRET_HASH (required if the app client is configured with a client secret), DEVICE_KEY.
  - SELECT_CHALLENGE: Respond to the challenge with USERNAME and an ANSWER that matches one of the challenge types in the AvailableChallenges response parameter.
  - SMS_MFA: Next challenge is to supply an ``SMS_MFA_CODE``that your user pool delivered in an SMS message.
  - EMAIL_OTP: Next challenge is to supply an EMAIL_OTP_CODE that your user pool delivered in an email message.
  - 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 activated 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 who are required to change their passwords after successful first login. Respond to this challenge with NEW_PASSWORD and any required attributes that Amazon Cognito returned in the requiredAttributes parameter. You can also set values for attributes that aren’t required by your user pool and that your app client can write. For more information, see RespondToAuthChallenge. Amazon Cognito only returns this challenge for users who have temporary passwords. Because of this, and because in some cases you can create users who don’t have values for required attributes, take care to collect and submit required-attribute values for all users who don’t have passwords. You can create a user in the Amazon Cognito console without, for example, a required birthdate attribute. The API response from Amazon Cognito won’t prompt you to submit a birthdate for the user if they don’t have a password.
  Note
  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.
  - MFA_SETUP: For users who are required to setup an MFA factor before they can sign in. The MFA types activated for the user pool will be listed in the challenge parameters MFAS_CAN_SETUP value. To set up software token MFA, use the session returned here from InitiateAuth as an input to AssociateSoftwareToken. Use the session returned by VerifySoftwareToken as an input to RespondToAuthChallenge with challenge name MFA_SETUP to complete sign-in. To set up SMS MFA, an administrator should help the user to add a phone number to their account, and then the user should call InitiateAuth again to restart sign-in.
- Session (string) –
  
  The session that should pass both ways in challenge-response calls to the service. If the caller must pass another challenge, they return a session with other challenge parameters. Include this session identifier in a RespondToAuthChallenge API request.
- ChallengeParameters (dict) –
  
  The challenge parameters. These are returned in the InitiateAuth response if you must pass another challenge. The responses in this parameter should be used to compute inputs to the next call ( RespondToAuthChallenge).
  
  All challenges require USERNAME. They also require SECRET_HASH if your app client has a client secret.
  - (string) –
    - (string) –
- AuthenticationResult (dict) –
  
  The result of the authentication response. This result is only returned if the caller doesn’t need to pass another challenge. If the caller does need to pass another challenge before it gets tokens, ChallengeName, ChallengeParameters, and Session are returned.
  - AccessToken (string) –
    
    Your user’s access token.
  - ExpiresIn (integer) –
    
    The expiration period of the authentication result in seconds.
  - TokenType (string) –
    
    The intended use of the token, for example Bearer.
  - RefreshToken (string) –
    
    Your user’s refresh token.
  - IdToken (string) –
    
    Your user’s ID token.
  - NewDeviceMetadata (dict) –
    
    The new device metadata from an authentication result.
    - DeviceKey (string) –
      
      The device key, an identifier used in generating the DEVICE_PASSWORD_VERIFIER for device SRP authentication.
    - DeviceGroupKey (string) –
      
      The device group key, an identifier used in generating the DEVICE_PASSWORD_VERIFIER for device SRP authentication.
- AvailableChallenges (list) –
  
  This response parameter prompts a user to select from multiple available challenges that they can complete authentication with. For example, they might be able to continue with passwordless authentication or with a one-time password from an SMS message.
  - (string) –

Exceptions

CognitoIdentityProvider.Client.exceptions.ResourceNotFoundException
CognitoIdentityProvider.Client.exceptions.InvalidParameterException
CognitoIdentityProvider.Client.exceptions.NotAuthorizedException
CognitoIdentityProvider.Client.exceptions.TooManyRequestsException
CognitoIdentityProvider.Client.exceptions.UnexpectedLambdaException
CognitoIdentityProvider.Client.exceptions.InvalidUserPoolConfigurationException
CognitoIdentityProvider.Client.exceptions.UserLambdaValidationException
CognitoIdentityProvider.Client.exceptions.InvalidLambdaResponseException
CognitoIdentityProvider.Client.exceptions.PasswordResetRequiredException
CognitoIdentityProvider.Client.exceptions.UserNotFoundException
CognitoIdentityProvider.Client.exceptions.UserNotConfirmedException
CognitoIdentityProvider.Client.exceptions.InternalErrorException
CognitoIdentityProvider.Client.exceptions.InvalidSmsRoleAccessPolicyException
CognitoIdentityProvider.Client.exceptions.InvalidEmailRoleAccessPolicyException
CognitoIdentityProvider.Client.exceptions.InvalidSmsRoleTrustRelationshipException
CognitoIdentityProvider.Client.exceptions.ForbiddenException