Tap to Phone - Android

Introduction

Purpose

This document references all the features and an Android integration guide for Cardknox Tap to Phone.

We’ll cover:

• Tap to Phone Application Overview

• How do you install the Tap to Phone application on your Android device?

• How to integrate a third-party merchant application with the Cardknox Tap to Phone application

Scope

This document is for Android developers looking to integrate the Cardknox Tap to Phone Helper application into their existing Android mobile app or web application.

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Overview of Tap to Phone Helper Mobile App

About

Tap to Phone allows merchants to accept payments using their mobile devices without an external terminal. Tap to Phone is a service application that will work only if the transaction is requested from other third-party merchant applications.

It offers deep link identities to third-party merchant applications to seamlessly integrate to fulfill their payment needs.

Requirements:

• Operating system of Android OS 10(Q) or later

• An Android device with NFC capabilities

• An Android device that is not rooted

• Android Device Settings:

  • Enable NFC and Contactless Payments settings

  • Disable Developer Options and USB Debugging settings

• Enable “Tap to Phone” within the Device Configuration settings within the Cardknox Mobile App

How to use Tap to Phone with the Cardknox Android App

• Enable the Tap to Phone Feature:

  • Open the Cardknox Android App.

  • Navigate to Settings -> Device Configuration

  • Select Tap to Phone.

• Install the Tap to Phone Helper App:

  • When prompted, install the Tap to Phone Helper app.

• Activate Tap to Phone:

  • Once the Tap to Phone helper app is installed, return to the Cardknox App and enable Tap to Phone.

How to install Tap to Phone using the Google Play Store

Download the Tap to Phone Helper application from the Google Play Store.

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Deep Linking

The deep linking feature allows a third-party application to use a predefined URL to open up the pre-installed Tap to Phone Helper mobile application to process a payment transaction.

The Tap to Phone Helper app will use the “xRedirectUrl” parameter to deliver the transaction results to the third-party application. Results are provided as query parameters, appended onto the value provided by the xRedirectUrl parameter.

The Tap to Phone Helper application's predefined URL is:

cardknox://tap.cardknox.com/transaction

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Supported Transaction Workflows

Tap to Phone Helper mobile application supports three (3) different transaction workflows.

1. Encrypted Payload – The third-party application will request the encrypted payload from the Tap to Phone helper application. To complete the transaction, send the server-side payload and other returned data to the Cardknox API. (see server-side transaction example)

Parameters	Required	Possible Values	Description
xCommand	Yes	cc:encrypt	If you send the xCommand value as cc:encrypt, the Tap to Phone helper will use the ‘Encrypted Payload’ workflow and return the encrypted payload in the transaction response.
xRedirectURL	Yes		A valid URL scheme defined inside the third-party application to receive transaction responses from the ‘Tap to Phone’ helper application

1. Single Use Token (SUT) – The merchant application will request a “Single Use Token” instead of the encrypted payload from the Tap to Phone helper application. Then, send the SUT and other returned data to the Cardknox API to complete the transaction.

Parameters	Required	Possible Values	Description
xCommand	Yes	cc:singleusetoken	If you send the xCommand value as cc:singleusetoken, the Tap to Phone helper will use the “Single Use Token (SUT)” workflow and return the SUT in the transaction response.
xRedirectURL	Yes		A valid URL scheme defined inside the third-party application to receive transaction responses from the ‘Tap to Phone’ helper application

1. Complete Transaction – With this workflow, the Tap to Phone helper application processes the complete transaction and returns the gateway response to the third-party application.

Parameters	Required	Possible Values	Description
xCommand	Yes	cc:sale, cc:save, cc:authonly, cc:credit	Cardknox transaction type
xKey	Yes		Your Cardknox API key
xRedirectURL	Yes		A valid URL scheme defined inside the third-party application to receive transaction responses from the ‘Tap to Phone’ helper application
*Any ‘Cardknox API’ parameter

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Transaction Parameters

Two types of parameters are supported by the Tap to Phone helper application.

1. Transaction API Specific – Use any Cardknox API parameters in the deep-link request. See Transaction API documentation. However, the below API parameters must be carefully designed to achieve the desired transaction result using the Tap to Phone helper.

Parameter	Description
xRedirectURL	A valid URL scheme defined inside the third-party application to receive transaction responses from the ‘Tap to Phone’ helper application
xCommand	This parameter is utilized to indicate the specific type of transaction that needs to be executed (cc:sale, cc:refund, cc:void, etc.). One caveat is that this must be defined as cc:encrypt for the ‘Encrypted Payload’ workflow or cc:singleusetoken for the ‘Single-Use-Token’ workflow. For the ‘Complete Transaction’ workflow, you can pass the usual Cardknox-specific xCommand values.

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Development and Debugging

Tap to Phone Development/Debugging Parameters – These are defined to troubleshoot issues quickly during the development phase.

The following is the list of Tap to Phone specific parameters that can be passed, along with the BBPOS Specific parameters, by the third-party merchant application in the deep link query string.

Parameter	Description	Possible Values	Default Value
debug	Set to TRUE to display logs in the Tap to Phone helper application.	TRUE/FALSE	FALSE
useSTG	This enables a staging gateway environment. Applicable only for ‘Complete Transaction’ workflow.	TRUE/FALSE	FALSE
doNotRedirect	Disables the redirect URL and displays the results/logs within the Tap to Phone helper app.	TRUE/FALSE	FALSE

All ‘debugging’ parameters are optional.

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How to Integrate Tap to Phone with Third-Party Android Applications

How to Setup Deeplink URL

Third-party merchant app developers can form URLs based on different transaction needs. Tap to Phone helper app will not cache any third-party request in the mobile application storage, and it's entirely driven by the transaction request passed through the deep link request.

Example of a deep link URL:

cardknox://tap.cardknox.com/transaction?xRedirectURL=mechant://pos.merchant.com/&xKey=XXXXXW23243HHDFJ&xEmail=[e-mail]&xAmount=12.00&xTip=1.0&xCommand=cc:sale&debug=True&useSTG=True&xAllowPartialAuth=true

Note that the above URL is corresponding to the “Complete Transaction” workflow since xKey is provided

Example of a deep link request, corresponding to the transaction response:

mechant://pos.merchant.com?xResult=D&xStatus=Declined&xError=Invalid%20Chip&xRefNum=102304545&xErrorCode=2034

The below response parameters and their explanations in the context of Tap to Phone helper.

Parameter	Description
xEncryptedPayload	This will contain the encrypted payload or single-use token if the transaction workflow is requested as an ‘encrypted payload’ or ‘single-use token’.
xSerialNumber	This will contain the rock value, that’s needed to perform the gateway request when the workflow is requested as ‘Encrypted Payload’ or ‘Single-Use-Token’.
xStatus	This will be a success or error when the workflow is requested as ‘Encrypted payload’ or ‘Single-Use-Token’. Containing the standard Cardknox gateway response values.
xCommand

You can refer to the API documentation for other response parameter definitions.

How to create a server-side call:

When running the server-side call to Cardknox, you must use the standard required API parameters. Reference the Transaction API for a list of parameters.

Additionally, the following parameters are required:

Parameter	Description	Example
xSerialNumber	The serial number value returned from the payload.	alP4n4-_92UPrgVI
xMobileTapType	Must equal to ‘TapToPhoneApp’	TapToPhoneApp
xEMVData	Pass the value of the returned encrypted payload (xEncryptedPayload).	AAABBgAAABgAAAAAAAABHgAAAIYAAAEeAQAAAAH_htzImhOJfEQlhxhrJsYZttThXPsWFZgUTYwxmxqaxdOXYnCvfoATExUgJb…

Server-side Request Example:

{
  "xKey": "dxxxcaxaxfxxfxxxxxxdxxcxcxfaax",
  "xCommand": "cc:sale",
  "xVersion": "4.5.9",
  "xSoftwareVersion": "1.0.12",
  "xAmount": "1.08",
  "xSoftwareName": "My Application ",
  "xEMVdata": "AAABBgAAABgAAAAAAAABHgAAAIYAAAEeAQAAAAH_htzImhOJfEQlhxhrJsYZttThXPsWFZgUTYwxmjxPBLLhkxwPcVZACZGDIntDDasmtAxxBWxxn_eAxlUbNxxAxxWtR",
  "xSerialNumber": "alN4n4-_92UPrgVI",
  "xMobileTapType": "TapToPhoneApp"
}

How to call a Deep Link URL to Invoke the Tap to Phone Helper Application

Once the deep link URL is formed, you can create an intent using the formed deep link URL and start the activity using the intent.

Thus Tap to Phone Helper application will be launched and start the workflow. Once the requested operations are complete, the result will be returned using the xRedirectUrl as well.

Here’s an example snippet of code to invoke the creation:

Uri myAction = Uri.parse(deepLinkUrl); 
// deepLinkUrl must be a string variable holding the deep link URL with all required parameters.
Intent intent = new Intent (Intent.ACTION_VIEW);
intent.setData (myAction);
startActivity(intent);