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This page will show you how to deploy GeeTest CAPTCHA V4 with the mainstream back-end coding languages.

The demo list in different back-end languages

Language address
C# https://github.com/GeeTeam/gt4_csharp_aspnetcoremvc_demo
Golang https://github.com/GeeTeam/gt4_golang_demo
Java https://github.com/GeeTeam/gt4-java-demo
Node https://github.com/GeeTeam/gt4_node_express_demo
PhP https://github.com/GeeTeam/gt4-php-demo
Python https://github.com/GeeTeam/gt4-python-demo
Ruby https://github.com/GeeTeam/gt4-ruby-demo

Secondary validation API

Interface information Description
API address http://gcaptcha4.geetest.com/validate
Supported protocol http/https
Request method GET/POST
Content type application/x-www-form-urlencoded
Response format json

Request parameters

Parameter Name Type Description
lot_number string Verify serial number
captcha_output string Verify output information
pass_token string Token of the verification
gen_time string Timestamp of the verification
captcha_id string CAPTCHA ID
sign_token string Verification signature

Response parameters

Generally, it only needs to deal with the return value when the verification succeeds and the verification fails. Also, the abnormal return value only occurs when the client does not request the correct method.

1 Example of successful verification return​

{
    "status": "success",  //request status
    "result": "success",  //the result of secondary verification
    "reason": "",  // the explaination of result
    "captcha_args": {  // verify the output parameters
        "used_type": "slide", 
        "user_ip": "127.0.0.1", 
        "lot_number": "4dc3cfc2cdff448cad8d13107198d473", 
        "scene": "反爬虫 anti crawler", 
        "referer": "http://127.0.0.1:8077/"
        // ...
    }
}

2 Example of validation failure return

{
    "status": "success",  //request status
    "result": "fail",  //the result of secondary verification
    "reason": "pass_token expire",  // the explaination of result
    "captcha_args": {  // verify the output parameters
        ...
    }
}

3 Example of request exception return

{
    "status": "error",  //request status
    "code": "-50005",  // error code
    "msg": "illegal gen_time",  // error message
    "desc": {  // error description
        "type": "defined error"
    }
}

Here is an example in Python:

def post(self):
    # 1. Initialize GeeTest parameter information
    captcha_id = '647f5ed2ed8acb4be36784e01556bb71'
    captcha_key = 'b09a7aafbfd83f73b35a9b530d0337bf'
    api_server = 'http://gcaptcha4.geetest.com'

    # 2. Get the verification parameters passed from the front end after user verification  
    lot_number = self.get_argument('lot_number', '')
    captcha_output = self.get_argument('captcha_output', '')
    pass_token = self.get_argument('pass_token', '')
    gen_time = self.get_argument('gen_time', '')

     # 3. Generate signature
     # Using standard hmac algorithms to generate signatures, using the user's current verification serial number lot_number as the original message, and the client's verification private key as the key
     # Using sha256 hash algorithm to hash message and key in one direction to generate the final signature
    lotnumber_bytes = lot_number.encode()
    prikey_bytes = captcha_key.encode()
    sign_token = hmac.new(prikey_bytes, lotnumber_bytes, digestmod='SHA256').hexdigest()

     # 4. Upload verification parameters to the second verification interface of GeeTest to verify the user verification status
     query = {
        "lot_number": lot_number,
        "captcha_output": captcha_output,
        "pass_token": pass_token,
        "gen_time": gen_time,
        "sign_token": sign_token,
     }

     # captcha_idParameter is recommended to be placed after url, so that when an exception is requested, it can be quickly located in the log according to the id
     url = api_server + '/validate' + '?captcha_id={}'.format(captcha_id)

     # Pay attention to handling interface exceptions, and make corresponding exception handling when requesting GeeTest secondary verification interface exceptions or response status is not 200
     # Guarantee that the business process will not be blocked by interface request timeout or service non-response
     try:
         res = requests.post(url, query)
         assert res.status_code == 200
         gt_msg = json.loads(res.text)
     except Exception as e:
        gt_msg = {'result': 'success', 'reason': 'request geetest api fail'}

        # 5. According to the user authentication status returned by GeeTest, the website owner conducts his own business logic
        if gt_msg['result'] == 'success':
            self.write({'login': 'success', 'reason': gt_msg['reason']})
        else:
            self.write({'login': 'fail', 'reason': gt_msg['reason']})
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