Databases Reference
In-Depth Information
key
Watermark
intersion
Original DB
Watermarked DB
(publish/distribute)
Watermark information
Watermarked DB
key
attacks
Watermark
detection
Watermark detected or not
(low false detection rates)
Suspicious DB
Watermark information
Innocent DB
Fig. 1.
Basic watermarking processes
Difference from multimedia watermarking
While the basic processes in database watermarking are quite similar to those
in watermarking multimedia data (which has long been rigorously studied
[10, 11, 4]), the approaches developed for multimedia watermarking cannot
be directly applied to databases because of the difference in data properties.
In general, database relations differ from multimedia data in significant ways
and hence require a different class of information-hiding mechanisms. Unlike
multimedia data whose components are highly correlated, database relations
consist of independent objects or tuples. The tuples can be added, deleted, or
modified frequently in either benign updates or malicious attacks. No existing
watermarking techniques for multimedia data are designed to accommodate
such tuple operations.
Classification model
The existing database watermarking schemes can be classified along various
dimensions, including:
•
Data type
: Different schemes are designed for watermarking different types
of data, including numerical data and categorical data.
•
Distortion to underlying data
: While some watermarking schemes in-
evitably introduce distortions/errors to the underlying data, others are
distortion-free.
•
Sensitivity to database attacks
: A watermarking scheme can be either
ro-
bust
or
fragile
to database attacks. A scheme is robust (fragile, respectively)
if it is dicult to make an embedded watermark undetectable (unchanged,
respectively) in database attacks, provided that the attacks do not degrade
the usefulness of the data significantly.
•
Watermark information
: The watermark information that is embedded
into a database can be a single-bit watermark, a multiple-bit watermark,
a fingerprint, or multiple watermarks in different watermarking schemes.
