Prerequisites:

• OpenSSL

In order to build a debug wheel, we first need to build a debug wheel for its dependency cffi.

1. Install pip dependencies:

    pip install -U wheel setuptools six asn1crypto ipaddress enum34
   

2. Download and extract cffi source (v1.12.3):

    https://foss.heptapod.net/pypy/cffi/-/archive/v1.12.3/cffi-v1.12.3.zip
   

3. Change to the root of the cffi repo.

4. Build a debug wheel:

    python_d setup.py build --debug
    python_d setup.py bdist_wheel
   

5. Install the debug wheel:

    python_d -m pip install --force-reinstall dist\cffi-1.12.3-cp37-cp37dm-win_amd64.whl
   

Now we can build the debug wheel for cryptography.

1. Set environment variables for OpenSSL (assuming default installation directory). Reference:

    set LIB=C:\OpenSSL-Win64\lib;%LIB%
    set INCLUDE=C:\OpenSSL-Win64\include;%INCLUDE%
    # This last line is needed if using OpenSSL version < 1.1.0
    set CRYPTOGRAPHY_WINDOWS_LINK_LEGACY_OPENSSL=True
   

2. Get cryptography source:

    git clone https://github.com/pyca/cryptography.git
    cd cryptography
    git checkout 2.7
   

3. Build wheel:

    python_d setup.py build --debug
    # Skip rebuilding, otherwise it will rebuild in release (not debug)
    python_d setup.py bdist_wheel --skip-build
   

The wheel can be found at dist\cryptography-2.7-cp37-cp37dm-win_amd64.whl.