Lossless Data Embedding in Electronic Inks

This paper presents a novel lossless data embedding algorithm for electronic inks. The proposed algorithm first computes the analytical ink-curve for each stroke as a set of smoothly concatenated cubic Bezier curves. During embedding, a set of data carrier points on the ink-curve are evaluated, perturbed, and then inserted into the original point array. Our proposed smooth ink-curve generation method iteratively refines the parameterization based on the local curve geometry. We demonstrate experimentally that the inserted points incur the least perceptional distortion on the marked ink-curves even after large mount of secret message is embedded. On extraction, the perturbed data carriers are identified and the original point array can be recovered. By subtracting these perturbed data carriers from their recomputed reference locations, we derive a sequence of perturbation vectors, from which the embedded secret message can be decoded. Based on the proposed embedding technique and the public-key cryptography, a hybrid secure ink authentication system is designed to secure electronic writings for tampering detection.