Provided are a device and method for generating an identification key using process variation during a bipolar junction transistor (BJT) process. A BJT may be produced by designing such that the effective base width of the BJT is at least a first threshold value but not more than a second threshold value, or, such that the total of the width of a second depletion region formed by connection with a collector region and the width of a first depletion region formed by connection with an emitter region, within a base region, differs from the width of the base region by a value that is at least the first threshold value but not more than the second threshold value. Whether or not there is a short circuit between the emitter region and the collector region is stochastically generated, and if ordinary turn-on voltage is not applied, whether or not there is a short circuit is identified.