Authentication of digital documents has always been an important issue to be resolved so that the electronic document systems can be securely implemented. Typically, two major classes of methods are proposed in the literature, i.e., digital signature or message authentication code-based approach and watermarking or data hiding-based approach. In this paper, we review the existing techniques on the authentication of digital documents; we also reviewed some recent patents relevant to authentication. Specifically, we focus on the data hiding and watermarking techniques for the authentication of electronic text and binary images, reviews of some techniques for the authentication of halftone, grayscale and color images are also included for comparison. The pros and cons of different techniques are compared. Finally, current developments are summarized and future directions are suggested.
Digital documents authentication, digital signature, message authentication code, binary images data hiding/watermarking, fragile watermarking, tampering detection and localization, authentication data, content digest, Authentication, digital documents, watermarking techniques, grayscale, tampering detection, localization, hybrid authentication, tamper-resistant, robust watermark, geometric transformation, flippability, Connectivity-Preserving, Pairs of contour edge, Asymmetric patterns, pixel distortion, Parity Attack, self-detecting, macro-blocks, blurring filter, wavelet transform, encryption technology, canonical form, HALFTONE IMAGES, pair toggling, salt-and-pepper, dot-area modulation, dot position modulation, embeddable location, de-quantization, de-zig-zagging, block cut-and-paste, semi-fragile