CB2A - Installment Payments | Computop Documents

Scenario – Installment Payments

You offer your customers payment by credit card based on installment payments
Customers agrees installment payment based on a total amount and a number of installment payments.
You use the pseudo card number to store and reuse the card data
IMPORTANT: The following initial payment is subject to the liability shift for you as a merchant. In the case of the subsequent payment, however, this expires, so that there is no liability shift.

credentialOnFile has been extended with type=installments and a few attributes describing the installment payment.

Credentials on File (CoF) – Initial Installment Payment

Applies to PaySSL.aspx + PayNow.aspx
3-D Secure is mandatory
Necessary adjustments:
- Example:
  - JSON object credentialOnFile with JSON parameter installment (3 keys included)
  - JSON object credentialOnFile with JSON parameter initialPayment and the value "true"
  - the amount used for the initial payment request is the amount authorized for 1st installment payment

Example Initial Subscription Payment for 3 installment payments with a total amount of 300,00 (EUR):

1
{
2
  "type": {
3
    "installments": {
4
      "total": 3,
5
      "curIdx": 1,
6
      "purchaseAmount": 10000
7
    }
8
  },
9
  "initialPayment": true
10
}

Credentials on File (CoF) – Subsequent Installment Payment

Applies to installment.aspx
3-D Secure is NOT mandatory
Necessary adjustments:
- Example:
  - The PayId from the initial payment is required for each subsequent installment payment.
  - Please always send the schemereferenceID from the initial payment so that the downstream systems can link the two transactions accordingly.
  - JSON object credentialOnFile with JSON parameter recurring (3 keys included)
  - JSON object credentialOnFile with JSON parameter initialPayment and value "false"
  - the total purchase amount (purchaseAmount) and total number of installment payments (total) remain the same, the current index increases with each authorization.
  - the amount used for the subsequent payment request is the amount authorized for subsequent installment payment

Example Subsequent Subscription Payment:

1
{
2
  "type": {
3
    "installments": {
4
      "total": 3,
5
      "curIdx": 2,
6
      "purchaseAmount": 10000
7
    }
8
  },
9
  "initialPayment": false
10
}

Request / Response installment.aspx

Request Elements

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

The following table describes the encrypted payment request parameters:

PayID in request always refers to initial Payment created with PaySSL or PayNow

PayID in response is the new payment process created for the subsequent installent payment created

Key

Format

CND

Description

Type

Paymethod for installment payment. "CB2A" must be specified.

MerchantID

ans..30

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

PayID

an32

ID assigned by Paygate for the payment, e.g. for referencing in batch files as well as for capture or credit request.

TransID

ans..64

TransactionID provided by you which should be unique for each payment

ReqId

ans..32

To avoid double payments or actions (e.g. by ETM), enter an alphanumeric value which identifies your transaction and may be assigned only once. If the transaction or action is submitted again with the same ReqID, Computop Paygate will not carry out the payment or new action, but will just return the status of the original transaction or action.

Please note that the Computop Paygate must have a finalized transaction status for the first initial action (authentication/authorisation). This does not apply to 3-D Secure authentications that are terminated by a timeout. The 3-D Secure Timeout status does not count as a completed status in which the ReqID functionality on Paygate does not take effect. Submissions with identical ReqID for an open status will be processed regularly.

Notice: Please note that a ReqID is only valid for 12 month, then it gets deleted at the Paygate.

credentialonfile

JSON

Object specifying type and series of transactions using payment account credentials (e.g. account number or payment token) that is stored by a merchant to process future purchases for a customer. Required if applicable.

RefNr

an12

Merchant’s unique reference number, which serves as payout reference in the acquirer EPA file. Please note, without the own shop reference delivery you cannot read out the EPA transaction and regarding the additional Computop settlement file (CTSF) we cannot add the additional payment data.

Notes:

CB2A requires
- fixed length of 12 characters, Paygate automatically align value to the right and add "0" (zero) to the left
- only characters (A..Z, a..z) and digits (0..9) are allowed, no characters like underscore, minus, ...
- RefNr is mandatory in case of "pre-authorization" by CB2A ( a MerchantID can be setup on Paygate either to handle "authorization" or "pre-authorization")

Amount

n..10

Amount in the smallest currency unit (e.g. EUR Cent). Please contact the Computop Helpdesk, if you want to capture amounts <100 (smallest currency unit).

Currency

Currency, three digits DIN / ISO 4217, e.g. EUR, USD, GBP. Please find an overview here: A1 Currency table

Capture

an..6

Determines the type and time of capture.

Capture Mode

Description

AUTO

Capturing immediately after authorisation (default value).

MANUAL

Capturing made by the merchant. Capture is normally initiated at time of delivery.

Delay in hours until the capture (whole number; 1 to 696).

UserData

ans..1024

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

MAC

an64

Hash Message Authentication Code (HMAC) with SHA-256 algorithm. Details can be found here:

Response Elements (installments)

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

pls. be prepared to receive additional parameters at any time and do not check the order of parameters

the key (e.g. MerchantId, RefNr) should not be checked case-sentive

Key	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 as well as for capture or credit request.
XID	an32	M	ID for all single transactions (authorisation, capture, credit note) for one payment assigned by Paygate
TransID	ans..64	M	TransactionID provided by you which should be unique for each payment
RefNr		O	Reference number as given in request
Status	a..20	M	Status of the transaction. Values accepted: AUTHORIZED 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	an8	M	Error code according to Paygate Response Codes (A4 Error codes)
UserData	ans..1024	O	If specified at request, Paygate forwards the parameter with the payment result to the shop.

Key

Format

CND

Description

mid

ans..30

MerchantID, assigned by Computop

PayID

an32

ID assigned by Paygate for the payment, e.g. for referencing in batch files as well as for capture or credit request.

XID

an32

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

TransID

ans..64

TransactionID provided by you which should be unique for each payment

RefNr

Reference number as given in request

Status

a..20

Status of the transaction.

Values accepted:

AUTHORIZED
FAILED

Description

ans..1024

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

an8

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

UserData

ans..1024

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