With the rise of the metaverse, more and more massively multi-user applications are to be expected. Because some of the data integrated in those virtual environments can be seen as highly sensitive, it is important to reinforce the applications with authentication methods to keep them safe. However, and while there are many authentication methods for 2D applications that could be regarded as safe enough, most of them do not provide a sufficient ease of use for VR applications. Henceforth, we propose an authentication method adapted to 3D user interfaces, based on toggling areas in a cubic grid. As illustrated in Figure 1, this leads to the construction of a voxel-based volume, which is an object simple enough to remember and playful to build, yet difficult to guess thanks to a high number of possibilities. For a more portable authentication method, the cubic grid is complemented by the generation of virtual keys representing the access a user has to a certain lock. The key acts as a metaphor that allows to easily share or grant access to secured objects or places in the VE.