captcha

Crystal library that generates image CAPTCHAs.

All credits goes to the example code in crystal-vips by @naqvis, and the users's discussion in this libvips issue.

Installation

You need install libvps correctly before use this shard.

check pre-requisites for details

1. Add the dependency to your shard.yml:

   dependencies:
     captcha:
       github: crystal-china/captcha

2. Run shards install

Usage

require "captcha"

captcha = CaptchaGenerator.new(length: 6)

# Return image as base64 string.
captcha.base64

# A <img> tag string which enbed the image in can use in HTML page.
captcha.img_tag # <img src="data:image/webp;base64,BASE64_ENCODED_IMAGE_DATA" />

# You can set image height or width like this: 
captcha.img_tag(height: "50px", width: "100px")

# you can use #write_html_file to preview how the captcha looks like in a html file.
captcha.write_html_file("test.html")

# return the underlying captcha code
captcha.code # nh8S8G

More usage, check spec

You should use this shards with a memory cache, consider refer to following links for a really production usecase of this shards with lucky.

create a cache.

config/application.cr

Generate a random unique signup_captcha_id and save to cookie.

Then use this random id as key, save the captcha code into cache and render the img_tag

src/actions/htmx/captcha.cr

get the captcha code from cache use cookie.

Get the captcha_id from cookie, then retrive the captcha code from the cache, check the equality.

src/actions/sign_ups/create.cr

limit

You can't create a fully static Crystal binary because it relies on libvips as a dependency. If that’s an issue for you, you might want to check out simple_captcha.

These two libraries should work interchangeably, so you shouldn’t need to change your code.

Contributing

1. Fork it (https://github.com/crystal-china/captcha/fork)
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Contributors

• Ali Naqvi creator and maintainer
• Billy.Zheng - maintainer