Declares an authentication flow and initiates sign-in for a user in the Amazon Cognito user directory. Amazon Cognito might respond with an additional challenge or an AuthenticationResult that contains the outcome of a successful authentication. You can't sign in a user with a federated IdP with InitiateAuth. For more information, see Authentication.
Amazon Cognito doesn't evaluate AWS 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.
NoteThis 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 AWS 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{
"AnalyticsMetadata": {
"AnalyticsEndpointId": "string"
},
"AuthFlow": "string",
"AuthParameters": {
"string" : "string"
},
"ClientId": "string",
"ClientMetadata": {
"string" : "string"
},
"Session": "string",
"UserContextData": {
"EncodedData": "string",
"IpAddress": "string"
}
}For information about the parameters that are common to all actions, see Common Parameters.
The request accepts the following data in JSON format.
Information that supports analytics outcomes with Amazon Pinpoint, including the user's endpoint ID. The endpoint ID is a destination for Amazon Pinpoint push notifications, for example a device identifier, email address, or phone number.
Type: AnalyticsMetadataType object
Required: No
The authentication flow that you want to initiate. Each AuthFlow has linked AuthParameters that you must submit. The following are some example flows.
Include the required InitiateAuth:AuthParameters for the flow that you choose.
The entry point for choice-based authentication with passwords, one-time passwords, and WebAuthn authenticators. 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. To activate this setting, your user pool must be in the Essentials tier or higher.
Username-password authentication with the Secure Remote Password (SRP) protocol. For more information, see Use SRP password verification in custom authentication flow.
Receive new ID and access tokens when you pass a REFRESH_TOKEN parameter with a valid refresh token as the value. For more information, see Using the refresh token.
Custom authentication with Lambda triggers. For more information, see Custom authentication challenge Lambda triggers.
Client-side username-password authentication with the password sent directly in the request. For more information about client-side and server-side authentication, see SDK authorization models.
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.
Type: String
Valid Values: USER_SRP_AUTH | REFRESH_TOKEN_AUTH | REFRESH_TOKEN | CUSTOM_AUTH | ADMIN_NO_SRP_AUTH | USER_PASSWORD_AUTH | ADMIN_USER_PASSWORD_AUTH | USER_AUTH
Required: Yes
The authentication parameters. These are inputs corresponding to the AuthFlow that you're invoking.
The following are some authentication flows and their parameters. Add a SECRET_HASH parameter if your app client has a client secret. Add DEVICE_KEY if you want to bypass multi-factor authentication with a remembered device.
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.
USERNAME (required)
SRP_A (required)
USERNAME (required)
PASSWORD (required)
USERNAME (required)
ChallengeName: SRP_A (when doing SRP authentication before custom challenges)
SRP_A: (An SRP_A value) (when doing SRP authentication before custom challenges)
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.
Type: String to string map
Key Length Constraints: Minimum length of 0. Maximum length of 131072.
Value Length Constraints: Minimum length of 0. Maximum length of 131072.
Required: No
The ID of the app client that your user wants to sign in to.
Type: String
Length Constraints: Minimum length of 1. Maximum length of 128.
Pattern: [\w+]+
Required: Yes
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 send an InitiateAuth request, 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 sign-up
Pre authentication
User migration
When Amazon Cognito invokes the functions for these triggers, it passes a JSON payload as input to the function. This payload contains a validationData attribute with the data that you assigned to the ClientMetadata parameter in your InitiateAuth request. In your function, validationData can contribute to operations that require data that isn't in the default payload.
InitiateAuth requests invokes the following triggers without ClientMetadata 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 Using Lambda triggers in the Amazon Cognito Developer Guide.
NoteWhen you use the ClientMetadata parameter, note that Amazon Cognito won't do the following:
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 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.
Type: String to string map
Key Length Constraints: Minimum length of 0. Maximum length of 131072.
Value Length Constraints: Minimum length of 0. Maximum length of 131072.
Required: No
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. When you pass the session ID to InitiateAuth, Amazon Cognito assumes the SMS or email message one-time verification password from ConfirmSignUp as the primary authentication factor. You're not required to submit this code a second time. This option is only valid for users who have confirmed their sign-up and are signing in for the first time within the authentication flow session duration of the session ID.
Type: String
Length Constraints: Minimum length of 20. Maximum length of 2048.
Required: No
Contextual data about your user session like the device fingerprint, IP address, or location. Amazon Cognito threat protection 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.
Type: UserContextDataType object
Required: No
{
"AuthenticationResult": {
"AccessToken": "string",
"ExpiresIn": number,
"IdToken": "string",
"NewDeviceMetadata": {
"DeviceGroupKey": "string",
"DeviceKey": "string"
},
"RefreshToken": "string",
"TokenType": "string"
},
"AvailableChallenges": [ "string" ],
"ChallengeName": "string",
"ChallengeParameters": {
"string" : "string"
},
"Session": "string"
}If the action is successful, the service sends back an HTTP 200 response.
The following data is returned in JSON format by the service.
The result of a successful and complete authentication request. This result is only returned if the user doesn't need to pass another challenge. If they must pass another challenge before they get tokens, Amazon Cognito returns a challenge in ChallengeName, ChallengeParameters, and Session response parameters.
Type: AuthenticationResultType object
This response parameter lists the available authentication challenges that users can select from in choice-based authentication. For example, they might be able to choose between passkey authentication, a one-time password from an SMS message, and a traditional password.
Type: Array of strings
Valid Values: 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
The name of an additional authentication challenge that you must respond to.
Collect the challenge response from the user and submit it in a RespondToAuthChallenge request. To link this response to the new request, include the Session response parameter in the next request.
Possible challenges include the following:
NoteAll of the following challenges require USERNAME and, when the app client has a client secret, SECRET_HASH in the parameters. Include a DEVICE_KEY for device authentication.
WEB_AUTHN: Respond to the challenge with the results of a successful authentication with a WebAuthn authenticator, or passkey, as CREDENTIAL. Examples of WebAuthn authenticators include biometric devices and security keys.
PASSWORD: Respond with the user's password as PASSWORD.
PASSWORD_SRP: Respond with the initial SRP secret as SRP_A.
SELECT_CHALLENGE: Respond with a challenge selection as ANSWER. It must be one of the challenge types in the AvailableChallenges response parameter. Add the parameters of the selected challenge, for example USERNAME and SMS_OTP.
SMS_MFA: Respond with the code that your user pool delivered in an SMS message, as SMS_MFA_CODE
EMAIL_MFA: Respond with the code that your user pool delivered in an email message, as EMAIL_MFA_CODE
EMAIL_OTP: Respond with the code that your user pool delivered in an email message, as EMAIL_OTP_CODE .
SMS_OTP: Respond with the code that your user pool delivered in an SMS message, as SMS_OTP_CODE.
PASSWORD_VERIFIER: Respond with the second stage of SRP secrets as PASSWORD_CLAIM_SIGNATURE, PASSWORD_CLAIM_SECRET_BLOCK, and TIMESTAMP.
CUSTOM_CHALLENGE: This is returned if your custom authentication flow determines that the user should pass another challenge before tokens are issued. The parameters of the challenge are determined by your Lambda function and issued in the ChallengeParameters of a challenge response.
DEVICE_SRP_AUTH: Respond with the initial parameters of device SRP authentication. For more information, see Signing in with a device.
DEVICE_PASSWORD_VERIFIER: Respond with PASSWORD_CLAIM_SIGNATURE, PASSWORD_CLAIM_SECRET_BLOCK, and TIMESTAMP after client-side SRP calculations. For more information, see Signing in with a device.
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.
Amazon Cognito only returns this challenge for users who have temporary passwords. When you create passwordless users, you must provide values for all required attributes.
NoteIn a NEW_PASSWORD_REQUIRED challenge response, you can't modify a required attribute that already has a value. In AdminRespondToAuthChallenge or RespondToAuthChallenge, set a value for any keys that Amazon Cognito returned in the requiredAttributes parameter, then use the AdminUpdateUserAttributes or 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 time-based one-time password (TOTP) MFA, use the session returned in this challenge from InitiateAuth or AdminInitiateAuth as an input to AssociateSoftwareToken. Then, use the session returned by VerifySoftwareToken as an input to RespondToAuthChallenge or AdminRespondToAuthChallenge with challenge name MFA_SETUP to complete sign-in.
To set up SMS or email MFA, collect a phone_number or email attribute for the user. Then restart the authentication flow with an InitiateAuth or AdminInitiateAuth request.
Type: String
Valid Values: 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
The required parameters of the ChallengeName challenge.
Collect the challenge response from the user and submit it in a RespondToAuthChallenge request. To link this response to the new request, include the Session response parameter in the next request.
All challenges require USERNAME. They also require SECRET_HASH if your app client has a client secret.
Type: String to string map
Key Length Constraints: Minimum length of 0. Maximum length of 131072.
Value Length Constraints: Minimum length of 0. Maximum length of 131072.
The session identifier that links a challenge response to the initial authentication request. If the user must pass another challenge, Amazon Cognito returns a session ID and challenge parameters.
Include this session ID in a RespondToAuthChallenge API request.
Type: String
Length Constraints: Minimum length of 20. Maximum length of 2048.
For information about the errors that are common to all actions, see Common Errors.
This exception is thrown when AWS WAF doesn't allow your request based on a web ACL that's associated with your user pool.
HTTP Status Code: 400
This exception is thrown when Amazon Cognito encounters an internal error.
HTTP Status Code: 500
This exception is thrown when Amazon Cognito isn't allowed to use your email identity. HTTP status code: 400.
HTTP Status Code: 400
This exception is thrown when Amazon Cognito encounters an invalid AWS Lambda response.
HTTP Status Code: 400
This exception is thrown when the Amazon Cognito service encounters an invalid parameter.
HTTP Status Code: 400
This exception is returned when the role provided for SMS configuration doesn't have permission to publish using Amazon SNS.
HTTP Status Code: 400
This exception is thrown when the trust relationship is not valid for the role provided for SMS configuration. This can happen if you don't 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
This exception is thrown when the user pool configuration is not valid.
HTTP Status Code: 400
This exception is thrown when a user isn't authorized.
HTTP Status Code: 400
This exception is thrown when a password reset is required.
HTTP Status Code: 400
This exception is thrown when the Amazon Cognito service can't find the requested resource.
HTTP Status Code: 400
This exception is thrown when the user has made too many requests for a given operation.
HTTP Status Code: 400
This exception is thrown when Amazon Cognito encounters an unexpected exception with AWS Lambda.
HTTP Status Code: 400
Exception that is thrown when you attempt to perform an operation that isn't enabled for the user pool client.
HTTP Status Code: 400
This exception is thrown when the Amazon Cognito service encounters a user validation exception with the AWS Lambda service.
HTTP Status Code: 400
This exception is thrown when a user isn't confirmed successfully.
HTTP Status Code: 400
This exception is thrown when a user isn't found.
HTTP Status Code: 400
The following example starts the user testuser in the passkey authentication flow. The user pool and app client have password, passkey, and OTP options. User verification is set to preferred for the user pool, so the user isn't required to have a passkey with user-verification support.
POST HTTP/1.1
Host: cognito-idp.us-east-1.amazonaws.com
X-Amz-Date: 20230613T200059Z
Accept-Encoding: gzip, deflate, br
X-Amz-Target: AWSCognitoIdentityProviderService.InitiateAuth
User-Agent: <UserAgentString>
Authorization: AWS4-HMAC-SHA256 Credential=<Credential>, SignedHeaders=<Headers>, Signature=<Signature>
Content-Length: <PayloadSizeBytes>
{
"AuthFlow": "USER_AUTH",
"ClientId": "1example23456789",
"AuthParameters": {
"USERNAME": "testuser",
"PREFERRED_CHALLENGE": "WEB_AUTHN"
}
}HTTP/1.1 200 OK
Date: Tue, 13 Jun 2023 20:00:59 GMT
Content-Type: application/x-amz-json-1.0
Content-Length: <PayloadSizeBytes>
x-amzn-requestid: a1b2c3d4-e5f6-a1b2-c3d4-EXAMPLE11111
Connection: keep-alive
{
"AvailableChallenges": [
"PASSWORD_SRP",
"PASSWORD",
"EMAIL_OTP",
"WEB_AUTHN"
],
"ChallengeName": "WEB_AUTHN",
"ChallengeParameters": {
"CREDENTIAL_REQUEST_OPTIONS": "{\"challenge\":\"[challenge string]\",\"timeout\":180000,\"rpId\":\"auth.example.com\",\"allowCredentials\":[{\"type\":\"public-key\",\"id\":\"[key ID]\",\"transports\":[]},{\"type\":\"public-key\",\"id\":\"[key ID]\",\"transports\":[\"internal\"]}],\"userVerification\":\"preferred\"}"
},
"Session": "AYABeC1-y8qooiuysEv0uM4wAqQAHQABAAdTZXJ2aWNlABBDb2duaXRvVXNlclBvb2xzAAEAB2F3cy1rbXMAS2Fybjphd3M6a21zOnVzLXd..."
}The following example requests sign-in for the user testuser in a user pool where they're eligible for sign in with email OTP.
POST HTTP/1.1
Host: cognito-idp.us-east-1.amazonaws.com
X-Amz-Date: 20230613T200059Z
Accept-Encoding: gzip, deflate, br
X-Amz-Target: AWSCognitoIdentityProviderService.InitiateAuth
User-Agent: <UserAgentString>
Authorization: AWS4-HMAC-SHA256 Credential=<Credential>, SignedHeaders=<Headers>, Signature=<Signature>
Content-Length: <PayloadSizeBytes>
{
"AuthFlow": "USER_AUTH",
"ClientId": "1example23456789",
"AuthParameters": {
"USERNAME": "testuser",
"PREFERRED_CHALLENGE": "EMAIL_OTP"
}
}HTTP/1.1 200 OK
Date: Tue, 13 Jun 2023 20:00:59 GMT
Content-Type: application/x-amz-json-1.0
Content-Length: <PayloadSizeBytes>
x-amzn-requestid: a1b2c3d4-e5f6-a1b2-c3d4-EXAMPLE11111
Connection: keep-alive
{
"AvailableChallenges": [
"PASSWORD_SRP",
"PASSWORD",
"EMAIL_OTP",
"WEB_AUTHN"
],
"ChallengeName": "EMAIL_OTP",
"ChallengeParameters": {
"CODE_DELIVERY_DELIVERY_MEDIUM": "EMAIL",
"CODE_DELIVERY_DESTINATION": "t***@e***"
},
"Session": "AYABeC1-y8qooiuysEv0uM4wAqQAHQABAAdTZXJ2aWNlABBDb2duaXRvVXNlclBvb2xzAAEAB2F3cy1rbXMAS2Fybjphd3M6a21zOnVzLXd..."
}The following example signs in the user mytestuser with analytics data, client metadata, and user context data for advanced security.
POST HTTP/1.1
Host: cognito-idp.us-west-2.amazonaws.com
X-Amz-Date: 20230613T200059Z
Accept-Encoding: gzip, deflate, br
X-Amz-Target: AWSCognitoIdentityProviderService.InitiateAuth
User-Agent: <UserAgentString>
Authorization: AWS4-HMAC-SHA256 Credential=<Credential>, SignedHeaders=<Headers>, Signature=<Signature>
Content-Length: <PayloadSizeBytes>
{
"AuthFlow": "USER_PASSWORD_AUTH",
"ClientId": "1example23456789",
"AuthParameters": {
"USERNAME": "mytestuser",
"PASSWORD": "This-is-my-test-99!",
"SECRET_HASH": "oT5ZkS8ctnrhYeeGsGTvOzPhoc/Jd1cO5fueBWFVmp8="
},
"AnalyticsMetadata": {
"AnalyticsEndpointId": "d70b2ba36a8c4dc5a04a0451a31a1e12"
},
"UserContextData": {
"EncodedData": "AmazonCognitoAdvancedSecurityData_object",
"IpAddress": "192.0.2.1"
},
"ClientMetadata": {
"MyTestKey": "MyTestValue"
}
}HTTP/1.1 200 OK
Date: Tue, 13 Jun 2023 20:00:59 GMT
Content-Type: application/x-amz-json-1.0
Content-Length: <PayloadSizeBytes>
x-amzn-requestid: a1b2c3d4-e5f6-a1b2-c3d4-EXAMPLE11111
Connection: keep-alive
{
"ChallengeName": "SOFTWARE_TOKEN_MFA",
"ChallengeParameters": {
"USER_ID_FOR_SRP": "mytestuser",
"FRIENDLY_DEVICE_NAME": "mytestauthenticator"
},
"Session": "AYABeC1-y8qooiuysEv0uM4wAqQAHQABAAdTZXJ2aWNlABBDb2duaXRvVXNlclBvb2xzAAEAB2F3cy1rbXMAS2Fybjphd3M6a21zOnVzLXd..."
}The following example exchanges a refresh token for access and ID tokens.
Sample RequestPOST HTTP/1.1
Host: cognito-idp.us-west-2.amazonaws.com
X-Amz-Date: 20230613T200059Z
Accept-Encoding: gzip, deflate, br
X-Amz-Target: AWSCognitoIdentityProviderService.InitiateAuth
User-Agent: <UserAgentString>
Authorization: AWS4-HMAC-SHA256 Credential=<Credential>, SignedHeaders=<Headers>, Signature=<Signature>
Content-Length: <PayloadSizeBytes>
{
"AuthFlow": "REFRESH_TOKEN",
"ClientId": "1example23456789",
"AuthParameters": {
"REFRESH_TOKEN": "eyJ123abcEXAMPLE",
"SECRET_HASH": "7P85/EXAMPLE"
}
}HTTP/1.1 200 OK
Date: Tue, 13 Jun 2023 20:00:59 GMT
Content-Type: application/x-amz-json-1.0
Content-Length: <PayloadSizeBytes>
x-amzn-requestid: a1b2c3d4-e5f6-a1b2-c3d4-EXAMPLE11111
Connection: keep-alive
{
"AuthenticationResult": {
"AccessToken": "eyJra456defEXAMPLE",
"ExpiresIn": 3600,
"IdToken": "eyJra789ghiEXAMPLE",
"TokenType": "Bearer"
},
"ChallengeParameters": {}
}For more information about using this API in one of the language-specific AWS SDKs, see the following:
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