![](https://csdnimg.cn/release/download_crawler_static/10693429/bg4.jpg)
4
Fig. 1. Diagram for depicting hierarchical structure of review and classification of watermarking and fingerprinting
techniques.
include: (1) preprocessing steps like data partitioning,
defining secret parameters etc.; (2) strategies to select
data for watermarking while using an optimization strat-
egy to ensure best watermark encoding; (3) defining
usability constraints to ensure quality of data during
watermark embedding; (4) embedding watermark sub-
ject to usability constraints; (5) computing a number of
parameters for use in watermark decoding stage, and
finally (6) generating the watermarked dataset for deliv-
ering it to the intended recipients. The brief description
of each submodule is given in the following.
Preprocessing. The optional preprocessing steps may
involve conversion of watermark information (images,
owner name etc.) to bit strings. The data is also usually
divided into logical groups using a particular given
criterion. Data partitioning is performed using secret
parameters to ensure that only the data owner knows
the information about the data partitioning.
Strategies. Strategies for selecting attribute(s), tuple(s),
watermark optimization, and watermark embedding
are different components of this sub-module. It is not
mandatory that a watermarking technique will utilize
all of the above-mentioned strategies.
Usability. Usability constraints are defined by the data
owner to identify bandwidth for watermarking. The
sole purpose of this sub-module is to ensure that the
watermarked data remains usable.
Watermark embedding. This sub-module embeds the
watermark in accordance with the encoding strategies
and data usability. The watermark embedding has to
cater a number of challenges by answering questions like
whether: (1) an inserted watermark brings distortions in
the original data; (2) an inserted watermark is fragile
(watermark is corrupted after even minor malicious
attacks), semi-fragile(watermark may tolerate minor ma-
licious attacks, but cannot tolerate major attacks), or
robust against attacks (can tolerate malicious attacks to a
certain level); (3) the inserted watermark is reversible or
irreversible (that is original data may or not be recovered
after watermark decoding); (4) an inserted watermark is
perceptible or imperceptible (but it is desired that rela-
tional database watermarking should be imperceptible).
Decoding parameters
Some of the parameters of watermark embedding
are usually required for watermark decoding, that are
calculated and saved by this submodule.
Watermarked dataset
The main output of watermark encoding module is
a watermarked dataset that subsequently delivered to
intended recipients.
3.2 Attacker Channel
An attacker – Mallory – can launch a number of ma-
licious attacks on the watermarked data. The attacker
channel module refers to all such possible attacks. The