Any electrically conductive materials, such as capacitors, resistors, on-chip resistors or wires can be used to create a temperature sensing security token. A temperature sensing security token may include a first resistor having a first side connected to a voltage source, a second resistor having a first side connected to the voltage source, an analog comparator having a first input connected to a second side of the first resistor and a second input connected to a second side of the second resistor and an output that represents at least one bit of a key, and an analog to digital converter having an input connected to the second side of the first resistor wherein an output of said analog to digital converter is related to temperature by a temperature coefficient of resistivity of the first resistor. The first resistor and the second resistor may have the same nominal resistance. The first resistor, the second resistor and the analog to digital comparator may be encased in the same package. The package may be configured to inhibit inspection and discovery of components contained in said package. A processor may be connected to a key register and to a temperature table wherein said processor may be configured to store the key bits in the key register and is configured to store data corresponding to temperature. The processor may be configured to store a time stamp associated with an entry in the temperature table. A communications interface may be connected to the processor.