Hope you're doing good.
We could really use your help here. We tried to figure out any encryption methods using velocity but failed to do so or find any relevant use case online. Here we have a little experience in velocity and thus looking for an expert who could at least guide us if not provide the code. Would be a great if you could help us out here.
Understand your situation, but I'm not comfortable providing what amounts to security consulting on a public forum. Once you're talking about AES (and especially b/c you're acting on behalf of a 3rd-party) that code should be developed in private. (Yes, security through obscurity is a fallacy, and someday the code should be safe to open-source, but for now this isn't the place to discuss.)