winsign Documentation Status

winsign is a python module for signing and manipulating Authenticode signatures in PE and MSI files.

  • Works on Python 3.7 and up.

  • Free software: MPL2


Most dependencies are specified in requirements/base.txt, however, currently you also need osslsigncode installed to perform signing. This utility can be fetched from your distribution’s package repository, or from e.g.

Signing MSIX/APPX files currently requires Mozilla’s fork of msix-packaging.


pip install winsign

CLI Usage

usage: winsign [-h] --certs CERTS --key PRIV_KEY [-n COMMENT] [-i URL] -d
               {sha1,sha256} [-t {old,rfc3161}] [-v] [-q]
               infile [outfile]

positional arguments:
  infile            unsigned file to sign
  outfile           where to write output to. defaults to infile

optional arguments:
  -h, --help        show this help message and exit
  --certs CERTS     certificates to include in the signature
  --key PRIV_KEY    private key used to sign
  -n COMMENT        comment to include in signature
  -i URL            url to include in signature
  -d {sha1,sha256}  digest to use for signing. must be one of sha1 or sha256
  -t {old,rfc3161}
  -v, --verbose
  -q, --quiet

Future plans

  • Stop using osslsigncode for PE signatures

  • Refactor code so that osslsigncode functionality is in its own module

  • Add python support for MSI, then we can drop dependency on osslsigncode


Highly recommended to create a virtualenv, then run:
  • python develop

  • make your changes to the source files

  • run local tests: tox

upon successful r+ and merging to master branch, you need to release a new version on PyPi.
  • edit to adjust the version

  • generate .whl file locally: python bdist_wheel

  • file will exist in: ./dist/winsign-{version}-py3-none-any.whl

  • (assuming you have pypi access to upload)

  • upload to pypi: twine upload –verbose dist/winsign-{version}-py3-none-any.whl


How it works

First we generate a dummy signature for the file using builtin keys. This uses the get_dummy_signature method.

We then take the extracted signature, and retrieve the ASN.1 SignedData object from it. We replace the certificates in the SignerInfo object with the real certificates. Then we can generate a signature over the new SignerInfo object with whatever mechanism we wish.

Finally, the resulting signature is injected into the original file.

API Documentation

Indices and tables