WeChat Pay will change the platform certificate from time to time due to certificate validity and for transaction security. WeChat Pay provides a range of APIs to help merchant backend system replace the certificate easily.
Tips：
Instructions：
It is recommended that developers use the central control server (i.e., unified management and distribution. Pay attention to the confidentiality and security of the certificate) to uniformly download and manage the WeChat Pay platform certificate. Other service logic servers conduct the signature verification and decryption of messages via the central control server.
Before WeChat Pay replaces the platform certificate, the certificate to be replaced will be added to the merchant's platform certificate list 24 hours in advance. The central control server needs to view the merchant's platform certificate list periodically and download the latest platform certificate in time.
When WeChat Pay replaces the platform certificate, different certificate serial numbers may exist in response requests and callback notifications received by the merchant, and the merchant should process it properly.
Rate limit rules for the API obtaining platform certificates: For a single Merchant ID, it is 1000/s.
For sensitive information encryption, it is recommended to use the latest platform certificate (that is, a certificate with a longer valid period).
Best practice：
Call the API on the central control server list.
Call regularly, with an interval of less than 12 hours.
Compare with the local certificate serial number list. A new certificate serial number indicates a certificate to be replaced.The old certificate needs to be cleaned up before being deprecated.
After obtaining the certificate, distribute it to each service API server.
Query parameter needs to be passed in the request URL.
Body parameter needs to be passed in the request JSON.
2. Request Parameters
None
3. Response Parameters
Response for successful request:
Name
Variable Name
Type
Required
Description
Certificate serial number
serial_no
string(40)
Yes
Serial numbers of certificates Example: 5157F09EFDC096DE15EBE81A47057A7232F1B8E1
Certificate enabling time
effective_time
string(32)
Yes
The time when the certificate took effect, in RFC3339 format. The enabling time for each platform certificate is fixed. Example: 2018-06-08T10:34:56+08:00
Certificate deprecation time
expire_time
string(32)
Yes
The time when the certificate expired, in RFC3339 format. Before replacing the platform certificate, the deprecation time of the old certificate will be modified 24 hours in advance, and the API returns both the new and the old platform certificates. After the replacement is complete, the API returns the latest platform certificate. Example: 2018-06-08T10:34:56+08:00
Certificate information
encrypt_certificate
object
Yes
Certificate information. For more information, see the description below.
Certificate information
Name
Variable Name
Type
Required
Description
Algorithm of encrypted certificate
algorithm
string(32)
Yes
Certificate encryption algorithm, with the key of API KEY, which needs to be set on the merchant platform.
Example: AEAD_AES_256_GCM
Random string of the encrypted certificate
nonce
string(12)
Yes
Random string of encrypted certificate
Example: 61f9c719728a
Additional data of encrypted certificate
associated_data
string(32)
Yes
Fixed value： certificate
Example: certificate
Encrypted certificate content
ciphertext
string(344)
Yes
With the API KEY and the above parameters, you can decrypt the plaintext of the platform certificate.The certificate plaintext is in PEM format.（Note： he certificate expiration time in PEM format may be inconsistent with the certificate deprecation time returned by the API when the certificate is replaced.)
Example: Y1IPF0kyRe+aJ7TK6cw08r1g/agxl16o
he procedure of how to decrypt the certificate is described as follows.
Obtain the merchant's key from the merchant platform and record it as "key".
For the algorithm described in "algorithm" (which is AEAD_AES_256_GCM), obtain the corresponding parameters "nonce" and "associated_data".
Use "key", "nonce" and "associated_data" to decrypt "ciphertext" (decode ciphertext with base64 before decrypting) to get the certificate content.
Tips：
For the API information of the "AEAD_AES_256_GCM" algorithm, seerfc5116。
Response for failed request:
Name
Variable Name
Type
Required
Description
Returned status code
code
string[1,32]
Yes
Error code. See the error code list for the enumerated values.
Returned information
message
string[1,256]
Yes
Returned message. It indicates the reason for the error if not empty.
Detailed error description
detail
object
No
It is returned when code is PARAM_ERROR. Details will be described below.
Detailed error description
Name
Variable Name
Type
Required
Description
The location of incorrect parameter
field
string[1,256]
Yes
If the incorrect parameter is in the JSON for request body, it is populated with the JSON Pointer pointing to this parameter. If the incorrect parameter is in the request URL or querystring, it is populated with the variable name of this parameter.
Value of the incorrect parameter
value
string[1,256]
Yes
Value of the incorrect parameter
Cause of error
issue
string[1,256]
Yes
Cause of error
Location of the incorrect parameter
location
string[1,256]
No
body: The incorrect parameter is in the JSON for request body url: The incorrect parameter is in the request URL query: The incorrect parameter is in the querystring of the request
1{2"code":"INVALID_REQUEST",3"message":"Parameter format verification error",4"detail":{5"field":"#/properties/payer",6"value":"1346177081915535577",7"issue":"与ALLOF schema不符",8"location":"body"9}10}
4. Error Codes
Error Message
Description
Solution
SYSTEM_ERROR
System error
System error. Please call the API again to initiate the query.
