A seal for a package includes a circuit having electrical characteristics that change under mechanical deformation and an attaching material coupled to the circuit and for attaching the circuit to the package. The seal is attached to the package and processed prior to shipping to establish an untampered state for the seal. This includes identifying a circuit on the sealed package according to a seal type associated with the seal, recording one or more characteristics associated with the circuit from the seal and storing the seal type and one or more characteristics associated with the circuit from the seal for later comparison. To detect tampering to the package, the seal type and corresponding seal and circuit for the seal is identified, the characteristics associated with a circuit from the seal are determined and compared with the previous characteristics recorded when the seal was initially applied to the package. If the comparison indicates that a mechanical deformation of the seal occurred, it is possible the seal and package were tampered with during shipment or delivery.