The SDK source from Github - no login is required. The latest release is in the Master branch, and bug fixes are in the Develop branch. Download the OCSDK as a zip file or clone the repository - we encourage you contribute bug-fix patches to the develop branch.
You can fork the directory in GitHub. Be aware, however, that even if the repository is private, all users with read access might be able to see your changes or commit activity. You might choose to download the source code and create a new independent repository.