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Hash generator for HTML inline styles and scripts

Project description

A small tool and library to generate the hashes of inline content that needs to be whitelisted when serving an HTML document with a Content-Security-Policy (because, as the name indicates, using unsafe-inline is not recommended).

You provide the HTML content (directly or through a file path/URL) then inlinehashes will parse the document and provide you with a list of elements that need to be explicitly added to the CSP header/tag.

The tool can be specially useful for scenarios where you use/include external software solutions in your website or application (such as a 3rd party CMS, etc), since it will allow you to detect changes after updates and edit you CSP accordingly.

Quick note: Always verify the content you are whitelisting and be careful when fetching live website data, since any existing XSS code will be included in the results.

At the moment this package is still in a very early stage, so it still doesn’t detect all possible items and the current API might change with future releases.

Inline content that is currently detected:

  • <script></script> tags

  • <style></style> tags

  • Many event handlers defined in element/tag attributes

  • Styles defined directly in the element/tag using the style attribute


Using pip you just need to pip install inlinehashes


The package can be used through 2 different ways, either by using the CLI interface or programmatically in your python project. Bellow you can find a quick summary of the available functionality.

CLI app

This is the available functionality:

usage: inlinehashes [-h] [-a {sha256,sha384,sha512}] [-o {table,json,plain}] [-t {all,script-src,style-src}] source

positional arguments:
  source                URL or local HTML file to check

  -h, --help            show this help message and exit
  -a {sha256,sha384,sha512}, --alg {sha256,sha384,sha512}
                        Hash algorithm to use (default: sha256)
  -o {table,json,plain}, --output {table,json,plain}
                        Format used to write the output (default: table)
  -t {all,script-src,style-src}, --target {all,script-src,style-src}
                        Target inline content to look for (default: all)

Here is an example of the output:

$inlinehashes -a sha384 -o json
    "content": "\n      html {\n        height: 100%;\n      }\n      ",
    "hash": "sha384-Ku20lQH5qbr4EDPzXD2rf25rEHJNswNYRUNMPjYl7jCe0eHJYDe0gFdQpnKkFUTv",
    "directive": "style-src",
    "line": 12,
    "position": 0


Here is the same example, but using python’s shell:

>>> import requests
>>> import inlinehashes
>>> content = requests.get("").text
>>> inlines = inlinehashes.parse(content)
>>> inlines
[Inline(line='17', position='0')]
>>> first = inlines[0]
>>> first.short_content
'\n      html {\n        height: 100%;\n      }\n      '
>>> first.sha256
>>> first.sha384
>>> first.sha512
>>> first.content
'\n      html {\n        height: 100%;\n      }\n      body {\n        background-image: url("data:image/png;base64,iVBORw0KGgoAAAANS...'


All contributions and improvements are welcome.

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