dr-captcha

Django rest captcha

Lightweight version of django-simple-captcha for work with django-rest-framework.

Features

• Speed: use cache instead of database
• Safety: union methods for generate key and image. (You can't generate many images for one key)
• Easy: only one rest api (for generate, refresh image).

Usage

Add RestCaptchaSerializer to your protected request validator:

from dr_captcha serializer import RestCaptchaSerializer
class HumanOnlyDataSerializer(RestCaptchaSerializer):
    pass

This code add to your serializer two required fields (captcha_key, captcha_value)

For provide this fields client(js code) should generate key:

> curl -X POST http:localhost:8000/api/captcha/ | python -m json.tool
{
    'image_type': 'image/png',
    'image_decode': 'base64',
    'captcha_key': 'de67e7f3-72d9-42d8-9677-ea381610363d',
    'captcha_value': '... image encoded in base64'
}

captcha_value - is base64 encoded PNG image, client should decode and show this image to human for validation and send letters from captcha to protected api. If human have mistake - client should re generate your image.

Note: See also trottling for protect public api

Install

> pip install django-rest-captcha

Add to your settings.py

Add to installed apps:

INSTALLED_APPS = (
    ...
    'dr_captcha',
)

Set dr_captcha settings (if you want), see defaults:

dr_captcha = {
    'CAPTCHA_CACHE': 'default',
    'CAPTCHA_TIMEOUT': 300,  # 5 minutes
    'CAPTCHA_LENGTH': 4,
    'CAPTCHA_FONT_SIZE': 22,
    'CAPTCHA_IMAGE_SIZE': (90, 40),
    'CAPTCHA_LETTER_ROTATION': (-35, 35),
    'CAPTCHA_FOREGROUND_COLOR': '#001100',
    'CAPTCHA_BACKGROUND_COLOR': '#ffffff',
    'CAPTCHA_FONT_PATH': FONT_PATH,
    'CAPTCHA_CACHE_KEY': 'dr_captcha_{key}.{version}',
    'FILTER_FUNCTION': 'dr_captcha.captcha.filter_default',
    'NOISE_FUNCTION': 'dr_captcha.captcha.noise_default'
}

We recommend using redis or local memory as cache with set parameter, with bigger value of MAX_ENTRIES:

CACHES={
    'default': {
        'BACKEND': 'django.core.cache.backends.locmem.LocMemCache',
        'LOCATION': 'rest-captcha',
        'MAX_ENTRIES': 10000,
    }
}

Add hooks to your app router (urls.py):

urlpatterns = [
    ...
    url(r'api/captcha/', include('dr_captcha.urls')),
]