Non-hosted sessions
Last updated: February 15, 2023
For full control over your 3D Secure (3DS) authentication flow, use non-hosted sessions. These will be initiated by your back end.
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Non-hosted sessions are suitable for authentications initiated for both browsers and mobile apps.
All Sessions API endpoints will accept a valid JSON web token (JWT) bearer token. These short-lived tokens can be generated using your client id and secret, which you will have received when you created your account.
Tokens must contain the scope sessions:browser for browser channel flows or sessions:app for native mobile app channel flows. If you are unsure of the channel you're going to use when you request the session, you can include both scopes.
All endpoints following the request to create a new session will also accept the session secret; creating a session will return a session_secret property, which can be used in the Authorization header of subsequent requests for that session.
The session_secret is short-lived randomly generated string that can only be used for actions taken on a specific session, reducing the chance of it being leaked. This way the front end does not have to have access to the client secrets required to create JWT tokens (which, if exposed to the front end, can risk being leaked to malicious third parties).
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Note that any endpoint accessible with session_secret can also be accessed with a valid JWT token. This can be useful if you intend to access the endpoints from your back end, for instance, because you proxy the requests instead of making them directly from the front end.
Learn more about exemptions.
In regions where SCA is mandated, following the Payment Services Directive (PSD2) means the initial cardholder-initiated transaction (CIT) payment will require SCA. As such, you must authenticate the CIT with a challenge in these mandated regions.
In your API request, set authentication_type to recurring or installment.
You will also need to send the recurring or installment object with the following required fields.
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For Visa payments, the initial customer-initiated transaction (CIT) to set up a recurring or installment series should be processed as a regular authentication. The additional fields described in the following fields are not required.
| Field name | Description |
|---|---|
Only applies to | Integer |
| Integer |
| String |
For non-recurring or non-installment payments, these fields will be ignored if they are sent to the API.
This is the first step to starting a 3DS authentication flow with Sessions. Authenticate the call with an access token and perform it from your back end.
For the full API specification, see the API reference.
post
https://api.checkout.com/sessions
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To increase the likelihood of frictionless authentication, add additional data fields when requesting a session.
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If you create a session with channel data, there is no need to update the channel data later on. A javascript_enabled field is required in the channel data to use 3DS version 2.2.0. See step 4 for more information.
You should receive a 202 - Accepted response, with a status of pending. It will also contain:
The session
id(prefixed bysid_), which you'll use to get the session details in the next step.A
_links.three_ds_method_urlURL, where the cardholder should be redirected to complete the Issuer Fingerprint, if the card supports this feature.A
next_actionsproperty, which will tell you what action(s) to take next.
With the introduction of 3DS version 2.2.0, you may receive a 2.2.0 value in the protocol_version field in the response.
Next, you need to gather the device data (meaning the details of the browser or mobile app that initiated the session) in order to make an authentication request. To do so, get the current session details with the following request.
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You can skip this step if your back end forwards the response of requesting a new session to your front end.
For the full API specification, see the API reference.
get
https://api.checkout.com/sessions/{session_id}
You will get a response with the property next_actions, which will tell you what you need to do next.
| Field name | Description |
|---|---|
string | The unique identifier of the session. |
array | Specifies what action to take to complete the session. Will be one of: |
string | The status of the session. Should be |
If there is no three_ds_method_url property available in the response, Sessions will automatically set the three_ds_method_completion property to U and continue the flow. You do not have to make a POST request to the Issuer Fingerprint endpoint. The following actions will be collect_channel_data, challenge_cardholder or complete, with their corresponding status pending, challenged or one of approved, declined, rejected or expired.
If one of the next actions after creating the session was issuer_fingerprint, this step must be completed before proceeding with the session.
This involves the customer's browser contacting the Access Control Server directly so that the latter can calculate a fingerprint of it.
To do this, you first need to construct the following payload:
This payload needs to be base64 encoded and sent to the three_ds_method_url property of the _links object of the session using a POST request and putting the base64 encoded data in a form field called threeDSMethodData.
This will trigger a POST redirect to the threeDSMethodNotificationURL with a form parameter named threeDSMethodData. This will be a base64 encoded payload that, when decoded, will look like the following:
If you do not wish to handle the notification manually you can use our interceptor application to do it for you. To do so, set the threeDSMethodNotificationURL with the applicable endpoint:
post
https://api.checkout.com/sessions-interceptor/3ds-method-notification
After you POST the threeDSMethodData, you can be notified about the completion by listening for a browser event as follows:
Where messageCallback is a function with the following signature:
And event.data will contain the following object:
In order to update the three_ds_method_completion property, you'll need to send a POST request to the issuer_fingerprint property of the _links object of the session.
Once you've received the message, the fingerprint has completed successfully and you can set the three_ds_method_completion property to Y.
If you don't receive the message within 10 seconds of initiating the flow, set this property to N. You will need to implement a timeout logic to account for this.
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The response you receive from the Notification of Completion will only contain threeDSServerTransID and not a value of Y/N/U. The three_ds_method_completion property is determined only by which route the Issuer Fingerprint step takes.
Alternatively, if the session was created without channel data and you need to submit this after the Issuer Fingerprint step, you can make a single POST request to /sessions/{id}/collect-data (see Step 4) with the three_ds_method_completion property in the payload. This means you don't need to make a separate PUT request to /sessions/{id}/issuer-fingerprint.
Once you've completed the relevant actions indicated by the next_actions property, you need to update the session with the collected device data to make the authentication request.
A javascript_enabled field is introduced in the channel data for 3DS version 2.2.0. If this field is not provided in the request, we will add it and default the value to true.
Note
If you created the session with channel data, there is no need to complete this step. This step will be handled by our mobile SDKs for mobile app flows.
For the full API specification, see the API reference.
put
https://api.checkout.com/sessions/{session_id}/collect-data
| Field name | Description |
|---|---|
required string | Indicates the interface (either |
required string | Exact content of the HTTP accept headers as sent to the 3DS Requestor from the cardholder’s browser. |
required boolean | Boolean that represents the ability of the cardholder browser to execute Java. The value is returned from the |
optional boolean | Boolean that represents the ability of the cardholder browser to execute JavaScript. Default: |
required string | Value representing the browser language as defined in IETF BCP47. Returned from the |
required string | Value representing the bit depth of the color palette for displaying images, in bits per pixel. Obtained from the cardholder's browser using the |
required string | Total height of the cardholder’s screen in pixels. Value is returned from the |
required string | Total width of the cardholder’s screen in pixels. Value is returned from the |
required string | Time difference between UTC time and the local time of the cardholder's browser, in minutes. |
required string | Exact content of the HTTP user-agent header. |
required string | IP address of the browser as returned by the HTTP headers to the 3DS Requestor. |
optional string | Indicates whether the 3DS Method successfully completed.
|
Once the update is received, an authentication request will be sent, returning an authentication response from the issuer with the outcome of the authentication: approved, attempted, unavailable, declined, rejected, or challenged.
This outcome sets the next_actions property in the update response, letting you know what to do next.
If an exemption was sent in the request and was successfully applied, you should expect an exemption object in the response.
| Field name | Description |
|---|---|
string | The unique identifier of the session. |
array | Specifies what action to take to complete the session.
|
string | The status of the session. Should be |
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This is only relevant for browser-based authentications. Our mobile SDKs will handle the challenge flow for mobile app authentications.
If, after completing the issuer fingerprint and channel data steps, the authentication is approved/declined immediately—the "frictionless" flow—you can proceed to complete the session.
If not, the cardholder will now be challenged to provide additional information to authenticate the payment—the "challenge" flow.
The next_actions field will contain the challenge_cardholder action (see example above). To proceed, create the challenge request (CReq) message as follows:
| Challenge window size value | Size |
|---|---|
01 | 250-400px |
02 | 390-400px |
03 | 500-600px |
04 | 600-400px |
05 | Full screen |
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The style of the challenge window style is dependent on the issuer, so the above sizes may not be exact. We recommend that you render the challenge inside a frame so you have full control over the final size on your page.
Once the CReq message is constructed, it must be base64 encoded and posted to the acs.url property of the session, in a form field named creq. Ensure that the encoded CReq message does not contain any padding.
If the CReq message was successful, the response will be the HTML needed to render the challenge.
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The challenge is dependent on the card issuer, so the actual HTML may look different, but there should be a form for the cardholder to complete the challenge.
If you want to be notified about the completion of the challenge, you can register an event handler on your page as follows:
Where messageCallback is a function with the following signature:
And event.data will contain the following object:
Where threeDSServerTransID is the transaction_id of the session and transStatus is one of the following values:
| Value | Description |
|---|---|
| Authentication/Verification Successful |
| Not Authenticated/Account Not Verified (transaction denied) |
| Authentication/Account Verification Could Not Be Performed (a technical or other problem, as indicated in ARes or RReq) |
| Attempts Processing Performed (not authenticated/verified, but a proof of attempted authentication/verification is provided) |
| Authentication/Account Verification Rejected (issuer has rejected transaction) |
Once the challenge has been completed, the session should move to a final state, allowing you to (optionally) complete the session.
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At this point the session should contain the eci and cryptogram (CAVV/AVV) properties needed for authorization, but these will only be returned when retrieving the session using a JWT token and not the session_secret. This is to protect them from leaking to the client side.
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The challenge flow should be completed within 15 minutes of initiating the flow. If this is not the case, the status of the challenge can be set to U.
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This is an optional step providing an easy way for you to be notified about the completion of the authentication.
Once the session is in a final state (approved, declined, rejected, unavailable, or attempted), you can choose to complete it.
This triggers a POST to the completion.callback_url field of the session and will respond with 204 if the call was successful or 500 otherwise. Alternatively, you can GET the session details to inspect it and verify its final status.
For the full API specification, see the API reference.
post
https://api.checkout.com/sessions/{session_id}/complete
If successful, we will use the callback_url to share the authentication outcome with you (see example below). If we receive a 2XX response from you, you will then get a successful 204 response with no content. If the payment was authenticated, you're now ready to authorize and complete the payment.
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If the authentication is approved ("response_code": "Y") or attempted ("A"), you can authorize the payment. If the authentication is unavailable due to technical issues ("U"), you can decide whether or not to proceed with the payment, based on your risk assessment.
With the introduction of 3DS version 2.2.0, you may receive a 2.2.0 value in the protocol_version field in the response.
| Field name | Description |
|---|---|
string, 36 chars | The unique identifier for the session. |
integer | The amount in the major currency. |
string | The three-letter ISO currency code. |
string (enum) | Indicates the status of the session. One of:
|
string | Indicates the type of payment this session is for. |
string (enum) | Indicates the category of the authentication request. One of:
|
string, maximum 100 chars | A reference you can later use to identify this payment, such as an order number. |
boolean | Indicates whether the authentication was successful. |
string, maximum 50 chars | The 3DS version used for authentication. Possible values:
|
string (enum) | The response from the DS or ACS which indicates whether a transaction qualifies as an authenticated transaction or account verification. One of:
|
string | The response from the direct server (DS) or access control server (ACS) which provides information on why the
|
string, 28 chars | A payment system-specific value provided as part of the access control server (ACS) registration for each supported direct server (DS). |
string, 2 chars | The electronic commerce indicator (ECI). |
boolean | Indicates whether this session involved a challenge. |
Below are the possible values of the status field, which tell you the current status of the session.
| Field name | Description |
|---|---|
| Authentication has been requested and the session has been started. The session |
| The 3DS server has updated the authentication with channel data collected by the SDKs and has created and sent an authentication request to the directory server. The access control server is now evaluating the data to decide whether to authenticate the transaction (frictionless) or challenge it. |
| The payment has been successfully authenticated (frictionless or challenged). |
| The payment has been authenticated by a stand-in service, because the access control server could not be reached or does not support 3DS natively. You can treat this as a successful authentication and proceed to authorization. |
| Authentication failed because of technical problems with the directory server or the issuer's access control server. |
| The transaction was not authenticated. The issuer denied the transaction. |
| The transaction was rejected. The issuer is rejecting the authentication and requests that authorization not be attempted. |
| Authentication has been requested but the issuer requires that the cardholder be presented with a challenge. |
| Authentication has been started and challenged, but the cardholder did not complete the challenge. |
| Authentication has been started but the channel data could not be collected, meaning an authentication request was not created. |
Below are the possible values for the next_actions field. When present, they identify what action to take in order to complete the session.
| Session type | Action | Description | Channel |
|---|---|---|---|
|
| Indicates that the SDK should collect the device data and pass it to the Sessions API so that the 3DS server can create an authentication request. | Browser and app |
| The issuer fingerprint is a step where the 3DS Method URL is used by the access control server before the authentication request to gather additional browser information to perform the risk assessment of the transaction. The use of the 3DS Method URL is optional. | Browser only | |
| This occurs after an issuer decides to challenge an authentication. You should create a challenge request and submit it to the issuer's access control server to obtain the details to render a challenge window for the cardholder to submit their credentials. | Browser and app | |
Hosted and non-hosted |
| No further actions are required. You can complete the session. | Browser and app |
When requesting a session, you can add additional data fields to increase the chances of a frictionless authentication. Below is a summary of the optional data you can add to your request.
| Type of data | Description and examples |
|---|---|
Client user data | Data that supports the specific authentication and information about the authentication method used. For example, your own credentials, and the issuer's credentials. |
Prior transaction information | For returning users and recurring transactions, gather and submit data with each following transaction. For example, when the recurring payment plan expires, payment references, and the authentication method used. |
Account type | The account type used in your request. Issuer's attach different risk profiles to different accounts. For example, credit or debit. |
Address match | Indicates whether the cardholder's shipping and billing address are the same. For example, how long they've had an account with you, and the number of purchases they've made in the last six months. |
User purchase history | Details of the cardholder's purchase history. For example, the number of purchases in the last six months, and the number of card attempts in the last 24 hours. |
Shipping address usage | Information about the use of the shipping address. For example, when the shipping address was first used, and whether the address name matches the cardholder's name. |
Suspicious account activity | Indicates whether you've experienced any suspicious activity on the cardholder's account. |
Cardholder information | Additional information you want to provide about the cardholder and their account with you. |
Cardholder email address | The email address associated with the cardholder's account. |
Cardholder shipping address | The cardholder's full shipping address. |
Installment payment data | For transactions that are being paid in installments, you can provide information about the maximum number of authorizations permitted within that payment plan. |
Prepaid and gift card transactions | Information about prepaid or gift card transactions. For example, the gift card amount, and whether or not the cardholder is pre-ordering a product. |
Shipping method | Indicate the shipping method being used for the order, or flag non-shippable items, like digital goods. For example, whether it's being shipped to a verified address on file, or being picked up by the cardholder from a local store. |
Delivery information | Information about the delivery, like the delivery email address or delivery timeframe. |