Patent ID: 8392713

Claim:
A computer readable storage medium that is not a signal and that is for activating a software application for execution on a designated computer, the computer readable storage medium having stored thereon computer executable instructions for performing the following steps: (a) computing an installation identifier representative of the software application and the designated computer; (b) receiving an activation code generated in accordance with the installation identifier and a blinding factor value, the activation code obtained using an offline medium; (c) computing a reference value as a function of the installation identifier; (d) computing a decryption key as a function of the activation code and a trial blinding factor value, the computing of the decryption key comprising: applying a specified hash algorithm to the activation code and the trial blinding factor a specified number of iterations to obtain a resulting hash value; and truncating the resulting hash value to a specified length; (e) using the decryption key to access an encrypted value representative of the installation identifier; (f) comparing the encrypted value to the reference value (g) utilizing a new trial blinding factor value with the activation code when the encrypted value does not match the reference hash value; and (h) computing a new decryption key as a function of the activation code and the new trial blinding factor value.