The invention is a method and system that is useful to authenticate
security paper. Specifically, the present invention relates to a method
and system that allows security paper to be authenticated more than once
without destroying the authentication mechanism. An authenticating
solution is applied to a surface of an authentic document or other
authentic security paper. Subsequent application of an activating solution
to a surface of a document containing the authenticating solution causes a
reversible color change allowing the document to be authenticated.
