A XenForo add-on that integrates ALTCHA as a privacy-friendly CAPTCHA alternative.
ALTCHA uses a proof-of-work challenge instead of image selection or third-party tracking. This add-on uses ALTCHA server-side verification without ALTCHA Sentinel, so it can run independently and does not require a paid ALTCHA Sentinel account.
Download and install the add-on from the XenForo Resource Manager:
https://xenforo.com/community/resources/roi-altacha-captcha.10127/
After installing the add-on, enable it from the XenForo Admin Control Panel.
Go to:
Admin Control Panel -> Setup -> Options -> User registration -> Enable CAPTCHA for guests
Select ALTCHA CAPTCHA and configure the required key.
The Private Secret Key is the ALTCHA HMAC secret used by your server to sign and verify CAPTCHA challenges.
Use a long, random string here. This value is not provided by ALTCHA and does not need to come from an external account. You can generate your own random secret and paste it into the field.
Keep this key private. Do not publish it, commit it to a public repository, or share it with users. If the key is leaked, generate a new random key and replace the old one.
Example format:
0378b0f84c4310279918d71a5647ba5d
Go to:
Admin Control Panel -> Setup -> Options -> [Roi] ALTCHA CAPTCHA
Available options:
Self-Hosted Widget JS URL: Optional. Use this if you want to load the ALTCHA widget JavaScript from your own server or CDN.Internationalization JS URL: Optional. Use this if you want to load a custom ALTCHA language file.Cost: Controls the proof-of-work difficulty. A higher value makes bots work harder, but also increases the time needed by real users' browsers.Checkbox & Switch: Controls the ALTCHA widget display type.Hides the ALTCHA logo icon: Hides the ALTCHA logo in the widget.Hides the ALTCHA attribution link: Hides the ALTCHA footer attribution link.
The default cost is 50000, which is a reasonable starting point for most forums. If users report that CAPTCHA takes too long, lower the value. If spam protection is too weak, raise it gradually.
This add-on uses ALTCHA server integration in "verifying without Sentinel" mode.
Because of this:
- It works independently.
- It is free to use.
- It does not require ALTCHA Sentinel.
- It does not support advanced ALTCHA Sentinel features.
Developed and tested with:
- XenForo 2.3.3
- PHP 8.3.14
Expected compatibility:
- XenForo 2.2+
- PHP 8.2+
This add-on is licensed under the MIT License. See the LICENSE file for more details.