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About Google Pay

What is Google Pay


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Google Pay is the fast, simple way to pay on sites, in apps and in stores using the cards saved to your Google Account. It protects your payment info with multiple layers of security and makes it easy to send money, store tickets or cash in on rewards – all from one convenient place.

TypePayments by eWallet EN


Notice: Regarding the liability shift in case of the card processing, please contact your Acquirer directly. Because Computop is not a direct contract partner, your Acquirer should specify the liability shift rules for each card brand.

On this page

How it works

When a user taps the Google Pay payment button, they see a payment sheet. It displays the payment methods they've saved to their Google Account and optional fields such as a shipping address. Users can then select a payment method quickly and provide a shipping address if required, or they can add new information.

In-app payment

The Google Pay API enables fast, simple checkout within your app, giving you convenient access to hundreds of millions of cards saved to Google Accounts worldwide.

These above screens represent a recommended Google Pay buy flow for a shopping cart experience.

These guidelines will help you implement Google Pay within your apps: https://developers.google.com/pay/api/android/guides/brand-guidelines.


Web payment

The Google Pay API enables fast, simple checkout on your website. This provides convenient access to hundreds of millions of cards that are saved to Google Accounts worldwide.

The above screens represent a recommended Google Pay buy flow for a shopping cart experience.

These guidelines will help you reference the Google Pay brand within your websites: https://developers.google.com/pay/api/web/guides/brand-guidelines.

Step by Step Set-Up Guide

Once you have decided to support Google Pay, there is a set of steps that need to be done. This guide is applicable for both, in-app and also web payments.

1. Verify if your Acquirer supports Google Pay, for the card networks supported and support for Android device tokens.

This information will be provided by Computop support team: helpdesk@computop.com.


2. If you already do not have one, request creation of Computop Merchant ID, unique identifier that represents a merchant in Computop Paygate platform. You need to use Computop Merchant ID also in Google Pay API.

Please contact Computop support team: helpdesk@computop.com.


3. Integrate Google Pay API: https://developers.google.com/pay/api/.

Apps: https://developers.google.com/pay/api/android/overview 

Web: https://developers.google.com/pay/api/web/overview


a. For payment tokenization method, choose “GATEWAY”, with following values:


const tokenizationSpecification = {

  type: “PAYMENT GATEWAY”,

  parameters: {

    'gateway': 'computop',

    'gatewayMerchantId': 'yourComputopMerchantID'

  }


b. For supported payment card networks, choose the ones your acquirer is supporting:

const allowedCardNetworks = ["AMEX", "DISCOVER", "JCB", "MASTERCARD", "VISA"];


c. The Google Pay API may return cards on file on Google.com (PAN_ONLY) and/or a device token on an Android device authenticated with a 3-D Secure cryptogram (CRYPTOGRAM_3DS).

Please make sure that you define CRYPTOGRAM_3DS only if your acquirer is supporting this functionality. Please contact Computop support team to verify this point if needed.

const allowedCardAuthMethods = ["PAN_ONLY", "CRYPTOGRAM_3DS"];

If you are operating in EEA region, please define CRYPTOGRAM_3DS only, as these payments are already Strong Customer Authenticated in Google Pay wallet and therefore compliant with PSD2 SCA regulation.

Note: If you receive Soft Decline in Response, you need to restart the payment with 3-D Secure authentication. 

This needs to be done by using Card Token received in Google Pay Response and following steps described in: Server-2-Server Integration EN 


d. In response from Google Pay API, you should receive Token similar to this:

You need to Base64 encode the whole token string and include it in Paygate parameter TokenExt.

Process flow chart

Google Pay process flow



Paygate interface

Definitions

Data formats

Format

Description

a

alphabetical

as

alphabetical with special characters

n

numeric

an

alphanumeric

ans

alphanumeric with special characters

ns

numeric with special characters

bool

boolean expression (true or false)

3

fixed length with 3 digits/characters

..3

variable length with maximum 3 digits/characters

enum

enumeration of allowed values

dttm

ISODateTime (YYYY-MM-DDThh:mm:ss)


Abbreviations

Abbreviation

Description

Comment

CND

condition


M

mandatory

If a parameter is mandatory, then it must be present

O

optional

If a parameter is optional, then it can be present, but it is not required

C

conditional

If a parameter is conditional, then there is a conditional rule which specifies whether it is mandatory or optional


Notice: Please note that the names of parameters can be returned in upper or lower case.


Calling the interface

Two transactions are created when making a credit card payment via Google Pay. In the Google Pay transaction the required credit card data are determined first and the actual credit card transaction is then carried out automatically. This takes place via a server-to-server connection and supports all usual credit card transaction options. The difference here, however, is that you don't transmit the credit card information, which you don't know. Instead, you transmit the Token generated by Google Pay, which contains the required credit card data in encrypted form.

In order to make a credit card payment with Google Pay, please use the following URL:


Notice: For security reasons, Paygate rejects all payment requests with formatting errors. Therefore please use the correct data type for each parameter.

The following table describes the encrypted transfer parameters for Google Pay. In addition you can submit any parameters that are applicable or required for a credit card payment (without credit card data). More information about this you can find within Card processing EN.

Parameter

Format

CND

Description

MerchantID

ans..30

M

MerchantID, assigned by Computop. Additionally this parameter has to be passed in plain language too.

TransID

ans..64

M

TransactionID which should be unique for each payment

RefNr

ns..30

O

Unique reference number

Amount

n..10

M

Amount in the smallest currency unit (e.g. EUR Cent)

Please contact the helpdesk, if you want to capture amounts < 100 (smallest currency unit).

Currency

a3

M

Currency, three digits DIN / ISO 4217

MAC

an64

M

Hash Message Authentication Code (HMAC) with SHA-256 algorithm

UserData

ans..1024

O

If specified at request, Paygate forwards the parameter with the payment result to the shop.

RTF

a1

O

Establishment of Credential on File Agreement (Cardholder agrees that his card data can be stored for further transactions).

Capture

ans..6

O

Determines the type and time of capture. AUTO: capturing immediately after authorisation (default value). MANUAL: capturing made by the merchant. <Number>: Delay in hours until the capture (whole number; 1 to 696).

OrderDesc

ans..64

M

Description of purchased goods, unit prices etc.

URLNotify

ans..256

O

Complete URL which Paygate calls up in order to notify the shop about the payment result. The URL may be called up only via port 443. It may not contain parameters: Use the UserData parameter instead.

TokenExt

ans..1024

M

Google Pay Token as JSON string in the Base64 format

Channel

a..10

O

Channel over which the order is processed.

Allowed values are WEBSITE and MOBILE_APP

Parameters for Google Pay


The following table describes the result parameters with which the Paygate responds to your system:

Parameter

Format

CND

Description

MID

ans..30

M

MerchantID, assigned by Computop

PayID

an32

M

ID assigned by Paygate for the payment, e.g. for referencing in batch files.

This ID refers to the credit card transaction unless an error occurs already at the Google Pay transaction.

XID

an32

M

ID for all single transactions (authorisation, capture, credit note) for one payment assigned by Paygate

TransID

ans..64

M

Merchant’s transaction number

RefNr

ns..30

O

Unique reference number

UserData

ans..1024

O

If specified at request, Paygate forwards the parameter with the payment result to the shop.

Status

a..50

M

OK or FAILED

Description

ans..1024

M

Further details in the event that payment is rejected. Please do not use the Description but the Code parameter for the transaction status analysis!

Code

n8

M

Error code according to Paygate Response Codes (A4 Error codes)

schemeReferenceIDans..64CCard scheme specific transaction ID required for subsequent credential-on-file payments, delayed authorizations and resubmssions.

Result parameters for Google Pay


Capture / Credit / Reversal

Captures, credits and reversals do not refer to the Google Pay transaction but directly to the credit card transaction. More information about this you can find within Card processing EN.

Batch processing via the interface

Captures, credits and reversals via batch do not refer to the Google Pay transaction but directly to the credit card transaction. More information about this you can find within the document Card processing EN.