Abstract—The protection of the contents of digital products is
referred to as content authentication. In some applications, to be able
to authenticate a digital product could be extremely essential. For
example, if a digital product is used as a piece of evidence in the
court, its integrity could mean life or death of the accused. Generally,
the problem of content authentication can be solved using semi-
fragile digital watermarking techniques. Recently many authors have
proposed Computer Generated Hologram Watermarking (CGH-
Watermarking) techniques. Starting from these studies, in this paper
a semi-fragile Computer Generated Hologram coding technique is
proposed, which is able to detect malicious tampering while
tolerating some incidental distortions. The proposed technique uses
as watermark an encrypted image, and it is well suitable for digital
image authentication.
Keywords—Asymmetric
cryptography,
Semi-Fragile
watermarking, Image authentication, Hologram watermark, Public-
Key Cryptography, RSA.
I. INTRODUCTION
ECENTLY many authors have proposed Computer
Generated
Hologram
Watermarking
(CGH
Watermarking) [1-5]. From these works, the potentiality
emerges about the possibility to use the CGH watermarking as
semi-fragile watermarking for images authentication [6, 7].
The specific
interest
in
semi-fragile watermarking
algorithms arises from the multitude of practical and
commercial applications where contents need to be strictly
protected, but the exact representation during exchange and
storage need not be guaranteed.
Digital images are gradually replacing their classical
analog counterparts. It is well known that digital images can
be altered or manipulated with ease. Furthermore, it is
generally impossible to tell whether a given image is authentic
or has been altered subsequently to capture by some readily
available digital image processing tools. This is an important
issue in, for example, legal applications, news reporting,
medical archiving, where peopl