=====
Usage
=====

Preparation
-----------

First, the utility provides the ``prepare`` functionality that does the following:

* Reading your template ``JSON`` file

* Converting the template to Python dictionary object.

* Converting the Python dictionary object back to a ``JSON`` file.

This is done to ensure that the tool will not tamper the template contents during the signing process.

To prepare a CloudFormation template to the signing process::

  cf_signer --prepare --template cf.template

This will create a cf-prepared.template file you can sign using the ``cf-signer`` tool.

Getting Started
---------------

To sign a CloudFormation template using the ``cf-signer`` tool::

  cf_signer --sign --template cf.template --key key.pem

To verify a signature of a CloudFormation template using the ``cf-signer`` tool::

  cf_signer --verify --template cf-signed.template --key pubkey.pem

You can also use cf_signer in your ``Python`` code to sign templates on your scripts:

.. code-block:: python

  from cf_signer.cf_signer import create_signature, verify_signature, prepare_template

  def main():
      prepare_result = prepare_template(target_file_path='tests/cf-unprepared.template')
      sign_result = create_signature(target_file_path='tests/cf.template', key_file_path='tests/key.pem')
      verify_result = verify_signature(target_file_path='tests/cf-signed.template', key_file_path='tests/pubkey.pem')