SpanKey: Dynamic Key Space Conditioning for Neural Network Access Control

arXiv:2604.12254v1 Announce Type: cross Abstract: SpanKey is a lightweight way to gate inference without encrypting weights or chasing leaderboard accuracy on gated inference. The idea is to condition activations on secret keys. A basis matrix $B$ defines a low-dimensional key subspace $Span(B)$; during training we sample coefficients $\alpha$ and form keys $k=\alpha^\top B$, then inject them into intermediate activations with additive or multiplicative maps and strength $\gamma$. Valid keys lie