A method and apparatus for increasing the entropy of a pseudorandom number (PRN). An intervener unit receives one or more signals from an authenticating device during a false authentication attempt. The intervener unit generates, in response to the one or more signals, a first PRN with an associated level of entropy, and transmits the first PRN to the authenticating device. The entropy level of the first PRN causes the authenticating device to generate during a subsequent authentication attempt a second PRN with a greater level of entropy than the first PRN.