The present invention relates to a unique dual color security paper authentication system. The authenticating system comprises the combination of a security paper together with a coordinated applicator. The paper contains a starch, an iodide salt and an acidic developer resin. The applicator of the system comprises two authenticating solutions. The first authenticating solution comprises one or more of a sulfonamide and a copper salt dispersed in a solvent. The second authenticating solution comprises one or more of a leuco and fluoran dye precursor dispersed in a solvent. On applying the authenticating solutions to authentic security paper, a first color of a starch iodine is expressed and a second color of a leuco or fluoran dye is expressed.