API callback (POST)

When the merchant system calls certain payment API, after OTT Pay API server receive payment success from payment channel, OTT Pay API server will send the payment result to the specified merchant system callback URL (the callback URL needs to be specified in the request parameter of Payment API, please refer to the specific API description).

Callback ( JSON Format):

Parameter	Type	Description
rsp_code	String	Response Code
rsp_msg	String	Response Message
merchant_id	String	Merchant ID
data	String	Encrypted Callback Data
md5	String	Information

Decryption Steps

Where data is the encrypted callback data, and the steps to decrypt it are as follows:

Concatenate the md5 string in the callback information and the merchant signkey provided by OTT Pay into a string in sequence.
Perform 16-bit md5 calculation on this concatenated string (indicate the result in uppercase) to get the key for decryption.
Apply Base64 decoding to the data string in the callback information and use the decryption key just obtained to perform standard AES decryption (AES working mode: ECB, key length: 128).

The decrypted data is in JSON format, and the content is as follows:

Parameter	Type	Sample Data	Description
finish_time	String Format yyyyMMddHHmmss	2024-01-08 16:29:03 CST	Transaction Time. The timestamp on the gateway when the transaction or the query was initiated by the client. Time zone is always calculated/displayed in DST irrespective of the merchant location.
merchant_id	String	CAMB006711	OTT Pay Merchant ID
order_id	String	17047528085325164	OTT Pay Payment ID.
order_status	String	authorised/captured	Payment status, please see Payment Status.
amount	String	9955	Transaction Amount
tip	String	0	Tip Amount
bizpay_order_id	String	JKZ2NDF5GC5PPJ65	Channel Order Number
remarks	String	20240108172641374	Remark
exchange_rate	String	5.057030	Currency exchang rate. This is only for Chinese Wallet Payment, not applicable for local card transaction.
sale_num	String		Merchant sales number. Invoice number for split payment.
convenience_fee	String	0	Fees. This is only for Chinese Wallet Payment, not applicable for local card transaction.
sub_openId	String	2088032832386722	Chinese Wallet Payment’s client ID.
reference	String	PTM3835286374203402	The reference number from 3rd party. This can be used for order IDs that generated by integrate merchant.

Decryption Example

This is the callback message with transaction data (JSON data format) as follows,

{
  "data": "vg8LJmi7ryeVxUTVfPC6N1l5ebL9cgn4MdlyLFEL6eqZQN+XvkvNhZevFmRitDLTUTcAcRnKYs407K3ePY2pslEgZYDoa9x80PBh95s7aqAYCwUlY5j9IUtklLlzqNT0mFPS7Fn5p6cr1EkBRVh82QHueCdkWVoFhvVHVYYrwQqF5cmPO+JNuDOei6goomz1QTfvv7M8zc4TT+r/EwKIDm4eoV9EeTk98gSiUy4+2ThLRrtZOFHqVP7OAjJ318X2EIKoZRA5lp42kdRVmd/mXi8aZpTVEiAT2GK7p3TNXFNXuPLcl6DhEUK9FLMrHcl4",
  "rsp_code": "SUCCESS",
  "rsp_msg": "success",
  "merchant_id": "ON00004652",
  "md5": "5A917182659DE14DCB3022CA6518F34F"
}

Step-1: Concatenate the md5 string in the callback information and the merchant signkey provided by OTT Pay into a string in sequence.

md5 String：

5A917182659DE14DCB3022CA6518F34F

signkey:

A8B5FE540E38A5A9

After concatenated：

5A917182659DE14DCB3022CA6518F34FA8B5FE540E38A5A9

Step-2: Perform 16-bit md5 calculation on the concatenated string (represent the result in uppercase) to get the key for decryption

BFE59D83C221F217

Step-3: Apply Base64 decoding to the data string in the callback message and perform AES decryption:

Chinese Wallet Payment transaction

{
  "amount": "3",
  "bizpay_order_id": "AL5909918566288061",
  "exchange_rate": "5.057030",
  "tip": "1",
  "merchant_id": "ON00004652",
  "order_id": "16795056216014900",
  "finish_time": "2023-03-23 01:21:53",
  "remarks": "可以",
  "sub_openId": "2088032832386722",
  "reference": "PTM3835286374203402"
}

Local Card Payment transaction

{
  "reference":"20240108172641374",
  "order_status":"captured",
  "amount":"9955",
  "bizpay_order_id":"JKZ2NDF5GC5PPJ65",
  "tip":"0",
  "merchant_id":"CAMB006711",
  "order_id":"17047528085325164",
  "finish_time":"2024-01-08 16:29:03 CST",
  "remarks":"20240108172641374"
}