A secure coding concept for pairwise images is revealed and implemented by the use of the proposed fractal mating coding scheme, in which the domain pools consist of the domain blocks selected from the pairwise images to explore both the intra- and interimage similarities. In addition to the pairwise relation, the mating ratios denoting the percentages of the domain blocks selected from both images are utilized. Further encryption can be achieved by the use of block mean permutation and mating of the fractal codes. The security level is high because the jointly coded images cannot be correctly reconstructed without all the required information. The computer experiments show that the coding performance can be greatly improved from conventional fractal coding schemes, and the intersecured purpose for pairwise images is successfully achieved.