13. The method of claim 12 , wherein in the remote search engine computer system returns a reference results page and the calculation of the reference score includes calculating a reference vector that includes at least a frequency of terms in the reference results page.
15. The method of claim 13 , wherein the challenge result includes at least a challenge answer and the calculation of the challenge reference score includes calculating an answer vector that includes at least a frequency of terms in the challenge answer, wherein the answer vector is compared with the reference vector to calculate the reference score for the first engine.