Tag: python licensing

Autodesk Revit plugin software licensing

Autodesk® Revit is a powerful building information software, which allows developers to extend its functionality through plug-ins that can be written in either Python or .NET. In order to monetize your plugin, we need to implement a license verification mechanism and a way to accept payments from prospective customers.

License verification

Python plugins

If your plugin is written in Python, you can use the Python2 version of our Python client. A simple license verification can be performed with the code below (your specific parameters can be found here):

from cryptolens_python2 import *
HelperMethods.ironpython2730_legacy = True

pubKey = "<RSAKeyValue><Modulus>sGbvxwdlDbqFXOMlVUnAF5ew0t0WpPW7rFpI5jHQOFkht/326dvh7t74RYeMpjy357NljouhpTLA3a6idnn4j6c3jmPWBkjZndGsPL4Bqm+fwE48nKpGPjkj4q/yzT4tHXBTyvaBjA8bVoCTnu+LiC4XEaLZRThGzIn5KQXKCigg6tQRy0GXE13XYFVz/x1mjFbT9/7dS8p85n8BuwlY5JvuBIQkKhuCNFfrUxBWyu87CFnXWjIupCD2VO/GbxaCvzrRjLZjAngLCMtZbYBALksqGPgTUN7ZM24XbPWyLtKPaXF2i4XRR9u6eTj5BfnLbKAU5PIVfjIS+vNYYogteQ==</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>"

res = Key.activate(token="WyIyNTU1IiwiRjdZZTB4RmtuTVcrQlNqcSszbmFMMHB3aWFJTlBsWW1Mbm9raVFyRyJd",\
                   rsa_pub_key=pubKey,\
                   product_id=3349, key="ICVLD-VVSZR-ZTICT-YKGXL", \
                   machine_code=Helpers.GetMachineCode())

if res[0] == None or not Helpers.IsOnRightMachine(res[0]):
    print("An error occurred: {0}".format(res[1]))
else:
    print("Success")
    
    license_key = res[0]
    print("Feature 1: " + str(license_key.f1))
    print("License expires: " + str(license_key.expires))

C# or VB.NET

If your plugin is either written in C# or VB.NET, you can use our .NET library instead. To add it to your project in Visual Studio:

  1. Right click on your project in the Solution Explorer and click on Manage NuGet Packages.
  2. Search for Cryptolens.Licensing and install it.
  3. Add the code-snippet form this page in the code where the plugin loads for the first time.

Accepting payments

One way to sell an Autodesk Revit plug-ins is by publishing them in the Autodesk App Store, where a basic licensing mechanism is already provided. The problem with this approach is that the licensing models available are quite limited (eg. you can only charge your customers once for the plug-in and they will be able to use it in perpetuity). For instance, selling your plug-in as a service (subscription model) is not supported.

A better approach is to still publish your plug-in in the Autodesk App Store and set it to be a free app. You can then ask your customers to get a separate license key to be able to unlock all features.

You can read more about various ways of selling your software in our help pages. I would also recommend to check out the available licensing models.

If you have any questions, please feel free to reach out!

Tips on monetizing Python applications

Python can be used to develop a variety of applications, either as plugins (eg. for Discord, AutoCAD, Autodesk Maya, etc) or standalone applications. In this post we will focus on how to monetize a standalone Python application.

Let’s say you have developed a Python application that classifies images (eg. using tensorflow or pytorch). To start selling it, there are just three things we need in place:

  • Code obfuscation – to ensure that no one can reverse engineer the application.
  • License verification – to ensure that customers need a license key before they can use the application (eg. so that you can restrict which features they can use and how long the license is valid).
  • Webshop – so that customers can obtain a license key to unlock functionality.

Code obfuscation

To obfuscate your application, multiple tools can be used. You can either use packages such as pyarmor that are made to obfuscate Python code or open source tools such as pyinstaller in combination with cpython (for most sensitive code).

License verification

A license key can be easily verified using the code below. You can find more information about the parameters here.

from licensing.helpers import Helpers
from licensing.models import Response, RSAPublicKey
from licensing.methods import Key

pubKey = "<RSAKeyValue><Modulus>sGbvxwdlDbqFXOMlVUnAF5ew0t0WpPW7rFpI5jHQOFkht/326dvh7t74RYeMpjy357NljouhpTLA3a6idnn4j6c3jmPWBkjZndGsPL4Bqm+fwE48nKpGPjkj4q/yzT4tHXBTyvaBjA8bVoCTnu+LiC4XEaLZRThGzIn5KQXKCigg6tQRy0GXE13XYFVz/x1mjFbT9/7dS8p85n8BuwlY5JvuBIQkKhuCNFfrUxBWyu87CFnXWjIupCD2VO/GbxaCvzrRjLZjAngLCMtZbYBALksqGPgTUN7ZM24XbPWyLtKPaXF2i4XRR9u6eTj5BfnLbKAU5PIVfjIS+vNYYogteQ==</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>"

res = Key.activate(token="WyIyNTU1IiwiRjdZZTB4RmtuTVcrQlNqcSszbmFMMHB3aWFJTlBsWW1Mbm9raVFyRyJd",\
                   rsa_pub_key=pubKey,\
                   product_id=3349, key="ICVLD-VVSZR-ZTICT-YKGXL", machine_code="test")

if res[0] == None:
    print("An error occured: {0}".format(res[1]))
else:
    print("Success")

Webshop

When you have obfuscation and license verification in place, we need a way for customers to be able to order a license key. If you already have Stripe, you can use the recurring billing module, which acts like an interface for plans defined in your Stripe account. In other cases, you can either use payment forms or a different platform (please read more here).

Questions? Please reach out to us at support@cryptolens.io 🙂

Python code for software licensing

Update 2019-12-04: We have updated the Python library so that it’s easier to obfuscate. Please check out the latest article with tips on monetizing Python applications (it covers code obfuscation, license verification and accepting payments).

Today, we released a library for license key verification in Python, freely available on GitHub. The code below checks license validity with the server (performing all the necessary cryptographic checks under the hood). Please run “pip install licensing” before running the code below.

from licensing.helpers import Helpers
from licensing.models import Response, RSAPublicKey
from licensing.methods import Key

pubKey = "<RSAKeyValue><Modulus>sGbvxwdlDbqFXOMlVUnAF5ew0t0WpPW7rFpI5jHQOFkht/326dvh7t74RYeMpjy357NljouhpTLA3a6idnn4j6c3jmPWBkjZndGsPL4Bqm+fwE48nKpGPjkj4q/yzT4tHXBTyvaBjA8bVoCTnu+LiC4XEaLZRThGzIn5KQXKCigg6tQRy0GXE13XYFVz/x1mjFbT9/7dS8p85n8BuwlY5JvuBIQkKhuCNFfrUxBWyu87CFnXWjIupCD2VO/GbxaCvzrRjLZjAngLCMtZbYBALksqGPgTUN7ZM24XbPWyLtKPaXF2i4XRR9u6eTj5BfnLbKAU5PIVfjIS+vNYYogteQ==</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>"

res = Key.activate(token="WyIyNTU1IiwiRjdZZTB4RmtuTVcrQlNqcSszbmFMMHB3aWFJTlBsWW1Mbm9raVFyRyJd",\
                   rsa_pub_key=pubKey,\
                   product_id=3349, key="ICVLD-VVSZR-ZTICT-YKGXL", machine_code="test")

if res[0] == None:
    print("An error occured: {0}".format(res[1]))
else:
    print("Success")

You can find more information the parameters, etc here.