An API response that is sent to the API caller synchronously with the GET method if the return_url field was set in the request with the targeted URL to handle the synchronous notification. The synchronous notification has two formats: the returnURL format and the XML format.
The transaction status cannot be confirmed by the data in the return page because the data can be changed manually.
The synchronous notification in returnURL:
The return page is responsible for redirection to the merchant website after the payment completed. Moreover, some data is also returned by the return page. The return page is one of the following pages in different languages:
Java: return_url.jsp
Php: return_url.php
C#: return_url.aspx.cs
The synchronous notification in Xml:
In many cases, one transaction process returns the process result only one time and the process result is in the XML format. With an XML synchronous notification returned, your current Alipay gateway page (https://mapi.alipay.com) will be automatically refreshed and output the process result from Alipay.
Verify the synchronous notification
After receiving a notification, you need to verify the authenticity of the signature to ensure the data contained in the notification is originated from Alipay without being modified during the transmission. By completing the following steps, the notification is verified and you can trust the notification.
MD5
Process the content of the notification sent from Alipay to get a pre-sign string.
a. Remove the sign and sign_type fields,
b. Sort the remaining fields in alphabetical order from A to Z
c. Connect all array values by the character of “&”.
If the returned notification is in XML, the returned parameters are contained in the nodes. You can take each node name as the parameter name and node value as the parameter value.
Take the synchronous response data of the create_forex_trade API as an example:
Get the value of the mysign parameter.
a. Append MD5 key to the end of the pre-sign string obtained in Step 2.
b. A value is generated by encrypting the string that consists of the pre-sign string and MD5 key by an MD5 encryption function. Assign this value to the mysign parameter.
Verify whether mysign = sign.
If the value of mysign, obtained in Step 3, and the value of sign, returned by Alipay, are equal, the verification of the signature is passed and you can trust the content of the notification.
RSA
Process the content of the notification sent from Alipay to get a pre-sign string.
a. Remove the sign and sign_type fields,
b. Sort the remaining fields in alphabetical order from A to Z
c. Connect all array values by the character of “&”.
If the returned notification is in XML, the returned parameters are contained in the nodes. You can take each node name as the parameter name and node value as the parameter value.
Take the synchronous response data of the create_forex_trade API as an example:
Encode the signature parameter (sign) into a bytecode string by using the Base64 scheme.
Use the RSA verification method to verify the signature. Pass the pre-sign string, the value of the sign parameter, and Alipay public key to the RSA verification method to check the verification result. For more information about the RSA verification method, see the following method in Demo Code.
To verify whether all API requests and responses are correctly handled, and whether user experiences are as expected, you can test Alipay payment features integrated with your applications in sandbox environment before going live in the production environment.
Sandbox environment is an environment where you can mimic the characteristics of the production environment and create simulated responses from all APIs the application relies on before going live. You can make API tests based on your own requirements including making a transaction, cancel, or refund a transaction, and so on. Before you access the Alipay Sandbox Portal to start the test, you need to make some preparations. See Prerequisites for details.
Before you test Alipay payment features in sandbox, you need to get the following preparations:
Download the demo code. If you haven’t done this, see demo code.
Get an Alipay merchant account. If you don’t have one, watch the video below to get yourself an Alipay merchant account and a quick overview of Alipay sandbox portal.
Use the Alipay sandbox gateway for testing. The URL of the sandbox gateway is: https://mapi.alipaydev.com/gateway.do?
Alipay sandbox test accounts
There are two types of test account: merchant test account and buyer test account.
Merchant test accounts:
Find the merchant test account information in the Alipay sandbox portal under Sandbox Accounts > Merchant. More than one test accounts are provided, and the accounts are sorted by payment feature. Find the correct one to use according to the payment feature you want to test. For example, to test the Alipay Auto Debit feature, use the account information provided under Alipay Auto Debit.
Login password: Use this password to login to the Alipay for Business website in the sandbox environment.
Signature key: Only MD5 signature is supported in the sandbox environment. RSA signature is not supported at this time.
Use the buyer test account to login to the Alipay sandbox app.
The buyer test account information can be found in the Alipay sandbox portal under Sandbox Accounts > Buyer.
Account balance: You can click Top Up to top up the buyer test account.
Download the Alipay sandbox app
The Alipay sandbox app supports only Android at this time.
1) In the Alipay sandbox portal, click Alipay Sandbox App from the menu on the left.
2) Take one of the following steps:
Scan the QR code displayed on the page with a QR code reader on your Android device. This will download and install the sandbox app to your device.
Click the download link to download the sandbox app to your computer.
To log in to the Alipay sandbox app, use the buyer test account and login password that are provided in the portal under Sandbox Accounts > Buyer.
To generate a digital signature, normally a key is required to sign the data. You must prepare the MD5 private key or the RSA/DSA private and public key pair to generate and verify a digital signature.
MD5 sign type
MD5 private key is required for generating and verifying MD5 signatures. The MD5 secret key is the 32-byte string which is composed of English letters and numbers. You can log in to the Global Portal to view the private key:
Log in with your user ID.
Click My Technical Service and enter your payment password. If you don't know your payment password, please contact Global Merchant Business Support
Check your MD5 Key. For example, the following graphic is an example of an MD5 Key:
RSA/DSA sign type
An RSA/DSA key pair contains the private key and the public key. The private key is required for generating the signature, while the public key is used for verifying the signature. The following steps assume that you are using RSA sign type, similar steps applied for generating and uploading DSA key pair.
Generating the private/public key pair
Many tools can be used to generate the RSA key pair. The following example illustrates the steps to generate the RSA key pair by using OpenSSL.
Install OpenSSL
For linux system, use the following command:
sudo apt-get install openssl
For windows system, download and then install OpenSSL from OpenSSL site.
Generate RSA key pair.
For linux system, use the following command:
After that, you can see two files under current folder, rsaprivatekey.pem and rsapublickey.pem. The former is the private key and the latter is the public key.
Notes:
For Java developers, remove the header, footer, carriage return, and space from the pkcs8 private key output in the console.
After creating a private key with openssl, if you use JAVA, you need to transform the private key into PKCS8 format; if you use .NET or PHP, no need to transform the private key into PKCS8 format.
-----BEGIN PUBLIC KEY-----MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDQWiDVZ7XYxa4CQsZoB3n7bfxLDkeGKjyQPt2FUtm4TWX9OYrd523iw6UUqnQ+Evfw88JgRnhyXadp+vnPKP7unormYQAfsM/CxzrfMoVdtwSiGtIJB4pfyRXjA+KL8nIa2hdQy5nLfgPVGZN4WidfUY/QpkddCVXnZ4bAUaQjXQIDAQAB-----END PUBLIC KEY-----
Exchange the public key
You need to exchange your public key with Alipay. Contact Global Merchant Technical Support and provide your PID and public key information. Alipay will then make configurations accordingly, and provide you Alipay public key.
For a transaction that has been successfully paid, the customer can request the merchant for refunding as long as the refunding period is still valid, and the merchant can make use of the refunding interface to complete the refunding, as illustrated.
For the integration of the refunding service, we would like to highlight:
The refunding service name is: alipay.acquire.overseas.spot.refund(REFUND);
To refund a transaction, the interface REVERSE is only applicable at the same day of the payment (GMT +8, Beijing time); on the other hand, the interface REFUND is applicable as long as the refunding period has not expired yet;
the refunding of a transaction can be full or partial, i.e. the refunding amount can respectively be the same as or less than the original transaction amount that has been paid; furthermore, for a transaction, multiple refunding request is allowed provided the sum of the amount of the multiple refunding request is less than or equal with the original transaction amount.
Except for "sign" and "sign_type", all other parameters used need to be signed.
Parameters without value don't need to be transmitted, nor to be included in the data to be signed;
At signing, the character set used to change the character into byte stream must be consistent with that specified in _input_charset;
If the parameter _input_charset is transmitted, it shall also be included in the data to be signed.
MD5 sign type
After the pre-sign string is generated:
Append the MD5 secret key to the pre-sign string to generate a new string.
Calculate the new string with the MD5 signature algorithm (by using the MD5 signature function).
The result 32-byte string is the signature, which is used as the value of the “sign” parameter.
RSA/DSA sign type
After the pre-sign string is generated, perform the following steps to generate the signature:
Use the RSA/DSA algorithm and the merchant private key to generate the signature.
Encode the signature to a string.
Then, use the string as the value of the “sign” parameter.
MD5 sign type
After receiving the character string of the response or notification from Alipay system, similar to the steps taken in Signing the data, append the MD5 secret key to the character string to generate a new string. Then, calculate this new string with the MD5 signature algorithm. After the 32-byte signature result string is generated, verify whether the value is equal to the value passed in the sign parameter. If Yes, the verification is passed.
RSA/DSA sign type
After receiving a response or notification, perform the following steps to verify the signature:
Use the RSA/DSA algorithm to calculate a message digest.
Use the RSA/DSA public key to de-sign the signature (the value of the sign field) to a message digest.
Compare the two message digests obtained in step 2 and step 3. If the digests are the same, then it indicates that the signed data has not been changed.
