To expand on what Sandalfoot said:
You must create you models in an external application, (Blender is popular and free, 3DSMax is free for non-commercial use) and then export them in a suitable format. There are many different model formats which target different things. Here are some:
- The Wavefront .OBJ format is very simple and easy to load, it is just a text based list of Vertices and Faces, with optional normals, UV textures and basic materials. The OBJ format is only used for static, non-animated models.
- The 3DS file format is binary format. This means that it is smaller and faster to load, but less intuitive. It is limited to storing 65536 Vertices. 3DS files can also be animated, but this is not as common.
- The DAE (COLLADA) file format is an XML based format. It is a free and open standard and can be animated. A bit complicated compared to .OBJ and .3DS but widely supported in many 3D packages.
If you are planning on writing your own importer for your program, then you should start with the .OBJ format. There are dozens of tutorials about loading .OBJ files with OpenGL and C++.
Alternatively, you can use a model loading library to load almost any model for you. ASSImp is a good one that supports .OBJ, .3DS, .DAE, and many more. This is the recommended path! Maintaining model loads in probably not your idea of fun, so you should use an external one.
And as to encryption and model protection? If you're really into encrypting you models (this is called DRM) or hardcoding them (just... bad), it won't still won't work. Each model must be uploaded to the graphics card, unencrypted. The unencrypted models can be intercepted with a fake OpenGL library, or some other method my pure and unsullied mind cannot comprehend. :) It is impossible for you to secure your models so there are three (typical) ways of dealing with this:
- Copyright them and have a good lawyer on the payroll. Sue people who steal your models. This is what big game studios generally do.
- Copyright them and hope they are not stolen. If they are stolen, send a letter and/or a lawyer. This is what some indie game devs and small studios do.
- Put your models under one of the CC licenses (or another similar license) and let people use your models but require attribution and other terms. You get free publicity whenever someone uses your models! This is what I would do, and what many open source projects end up doing.