Privacy protection for RFID with hidden subset identifiers

We propose very simple and cheap but nevertheless effective protection against privacy threats for RFID-tags. For the hidden subset RFID-tags proposed in this paper, the ID string presented by an RFID-tag evolves rapidly. It is is not the bit value that enables one to recognize a tag. Instead, a reader detects some invariant properties that are hard to be recognized by a curious illegitimate reader. The solution is not based on any cryptographic primitive, it relies only on properties of random sets and on linear mappings between vector spaces. The solution proposed is well suited for low-end devices, since all mechanisms can be easily implemented by circuits of a small size.