# documentation:2.0:captcha
Keywords: documentation,2.0,captcha

# Captcha

## Presentation

Captcha is a security mechanism aimed to prevent robots to submit forms.

Captchas are available on the following forms:

- Login form: where user enters login and password to authenticate
- Password reset by mail form: where user enters mail to recover a lost password
- Register form: where user enters information to create a new account

We use the Perl module GD::SecurityImage to generate images, you need to install it if you enable Captcha feature.

## Configuration

Go in `General parameters` > `Portal` > `Captcha`:

- Activation in login form: set to 1 to display captcha in login form
- Activation in password reset by mail form: set to 1 to display captcha in password reset by mail form
- Activation in register form: set to 1 to display captcha in register form
- Size: length of captcha