Sergio Vicente Denser Pamboukian

Watermarking JBIG2 text region for image authentication

An authentication watermarking technique (AWT) inserts hidden data into an image in order to detect any accidental or malicious alteration to the image. AWT usually computes, using a secret-key, the message authentication code (MAC) of the image, and somehow inserts MAC into the image itself. The authentication verification is performed using the same secret-key used in the insertion. JBIG2 is an international standard for lossy and lossless binary image compression. It decomposes the image into several regions (text, halftone, line-art) and encodes each one using the most appropriate method. This paper proposes a novel data-hiding technique to embed the data into the text region of a JBIG2 file. We, then, use it to create an AWT for a JBIG2-encoded image. The embedded data can be extracted from either the JBIG2 file itself or the binary image obtained by decoding the JBIG2 file.

New public-key authentication watermarking for JBIG2 resistant to parity attacks

An authentication watermark is a hidden data inserted into an image that allows detecting any alteration made in the image. AWTs (Authentication Watermarking Techniques) normally make use of secret- or public-key cryptographic cipher to compute the authentication signature of the image, and inserts it into the image itself. Many previous public-key AWTs for uncompressed binary images can be attacked by an image adulterating technique named “parity attack.” JBIG2 is an international standard for compressing bi-level images (both lossy and lossless). The creation of secure AWTs for compressed binary images is an important practical problem. However, it seems that no AWT for JBIG2 resistant to parity attacks has ever been proposed. This paper proposes a new data-hiding method to embed information in the text region of JBIG2 files. Then, we use this technique to design a new AWT for JBIG2-encoded images resistant to parity attacks. Both the secret- and public-key versions of the proposed AWT are completely immune against parity attacks. Moreover, watermarked images are visually pleasant, without visible salt and pepper noise. Image authenticity verification can be performed in either JBIG2 file itself or in the binary image obtained by decoding the JBIG2 file.