Kaptĉapelo is a simple [Kocaptcha](https://github.com/koto-bank/kocaptcha)-compatible CAPTCHA server, to keep out robots and people with dubious intent. Rather than auto-generated challenges like Kocaptcha, though, Kaptĉapelo lets you create shiny, pretty, _custom_ challenges.
Since Kaptĉapelo is a kinda-sorta drop-in replacement for Kocaptcha, you can [use it as CAPTCHA](https://docs-develop.pleroma.social/backend/configuration/cheatsheet/#captcha) for your [Pleroma](https://pleroma.social) server.
* A Common Lisp implementation. I’d recommend [Steel Bank Common Lisp](http://www.sbcl.org/), which is robust and available on many operating systems under the package-name `sbcl`.
* [Quicklisp](https://quicklisp.org/), a “package-manager” for Common Lisp libraries.
To install these, you can run the following commands (replacing `guix` with your package-manager of choice)…
You’ll probably be running Kaptchapelo through a reverse proxy; here’s how you can add it to an existing server definition with [nginx](https://nginx.org/):
```
server {
[…]
location /new {
set $target http://localhost:5001;
proxy_buffering off;
proxy_pass http://localhost:5001;
}
location /captcha/ {
set $target http://localhost:5001;
proxy_buffering off;
proxy_pass http://localhost:5001;
}
[…]
}
```
That is to say, you don’t need a dedicated subdomain!
### Custom captchas
Making custom captchas is easy! A challenge is simply a PNG file (question) and a TXT file (answer).
Note that the PNG and TXT files should have the same name (`bird.png` and `bird.txt`, not `bird2.png` and `bird1.txt`), and that the TXT answer should consist of one line with _no_ newline.
A peek through this repository’s example captchas (in `./captcha/`) should give you the idea.
### Captcha directory
It’s likely you’ll want to provide a custom directory in which to store your captchas; no problem! Just edit the aforementioned `run-kaptchapelo.lisp` script, which contains a line…
