A tamper-resistant packaging approach protects an integrated circuit (100) from undesirable access. According to an example embodiment of the present invention, data is encrypted as a function of the state of a plurality of magnetically-responsive circuit elements (130-135) and then decrypted as a function of the state (130-135). A package (106) is arranged to prevent access to the integrated circuit and having magnetic particles (120-125) therein. The magnetic particles (120-125) are arranged to cause the magnetically-responsive circuit elements (130-135) to take on a state that is used to encrypt the data. The state of these elements is again accordingly used to decrypt the data (e.g., as a key). When the magnetic particles are altered, for example, by removing a portion of the package, the state of one or more of the magnetically-responsive circuit elements is changed, thus rendering the state incapable of being used for decrypting the data.