def generate_adhoc_ssl_context() -> ssl.SSLContext:
    """Generates an adhoc SSL context for the development server."""
    import atexit
    import tempfile

    cert, pkey = generate_adhoc_ssl_pair()

    from cryptography.hazmat.primitives import serialization

    cert_handle, cert_file = tempfile.mkstemp()
    pkey_handle, pkey_file = tempfile.mkstemp()
    atexit.register(os.remove, pkey_file)
    atexit.register(os.remove, cert_file)

    os.write(cert_handle, cert.public_bytes(serialization.Encoding.PEM))
    os.write(
        pkey_handle,
        pkey.private_bytes(
            encoding=serialization.Encoding.PEM,
            format=serialization.PrivateFormat.TraditionalOpenSSL,
            encryption_algorithm=serialization.NoEncryption(),
        ),
    )

    os.close(cert_handle)
    os.close(pkey_handle)
    ctx = load_ssl_context(cert_file, pkey_file)
    return ctx
Generates an adhoc SSL context for the development server.
src/werkzeug/serving.py