  We investigate the privacy of two approaches to (biometric) template
protection: Helper Data Systems and Sparse Ternary Coding with Ambiguization.
In particular, we focus on a privacy property that is often overlooked, namely
how much leakage exists about one specific binary property of one component of
the feature vector. This property is e.g. the sign or an indicator that a
threshold is exceeded.
  We provide evidence that both approaches are able to protect such sensitive
binary variables, and discuss how system parameters need to be set.
