A physically unclonable function circuit (PUF) is used to generate a fingerprint value based on the uniqueness of the physical characteristics (e.g., resistance, capacitance, connectivity, etc.) of a tamper prevention (i.e., shielding) structure that includes through-silicon vias and metallization on the backside of the integrated circuit. The physical characteristics depend on random physical factors introduced during manufacturing. This causes the chip-to-chip variations in these physical characteristics to be unpredictable and uncontrollable which makes more difficult to duplicate, clone, or modify the structure without changing the fingerprint value. By including the through-silicon vias and metallization on the backside of the integrated circuit as part of the PUF, the backside of the chip can be protected from modifications that can be used to help learn the secure cryptographic keys and/or circumvent the secure cryptographic (or other) circuitry.