Cryptography Reference
In-Depth Information
extraction fails, it is forged. If the extraction succeeds, but some discrepancy
exists between the external and the internal layer, it is apparently tampered.
Otherwise, the document is authentic.
Type-2 forgery detection
A Type-2 forgery protective digital certificate needs some additional scheme.
It is a one-way scrambled key for embedding and extracting the original
document data. The detailed scheme is described in other literature [8].
The capability of forgery detection depends on the fragileness of the
steganography that we use. We knew, throughout our experiment, that em-
bedding JPG files in a PNG vessel image is the best. However, this is beyond
the scope the topic here.
8.2.3 Media Database System Application
Most media database system has varieties of metadata associated with the
content of the respective data. They are used for content retrieving. A media
database system today handles the media data and the metadata in separate
data categories, but tightly associated with each other within the DBMS. One
troublesome problem is as follows. When someone creates and edits metadata,
he/she must work using an editing system combined with the DBMS. This
means the work place for metadata handling is limited around the DBMS. So,
editing metadata off-line is di
cult in some situation.
Another problem is the di
culty of a local database re-organization. This
happens when someone wants to download a set of specially localized media
data from a large database system and tries to re-organize or merge with
another local database. He/she may able to collect and download the media
data, but may not able to download the associated metadata easily as he/she
wants to do.
These problems are caused by the fact that media data and the metadata
are separately handled in the system and associated with media data under
the tight control of the DBMS.
One solution to this problem is that each media data carries its own meta-
data as well as some additional data that may be used in some other system
in an embedded form according to a steganography such as BPCS. This ap-
plication of the steganography makes use of the property (D) above. We are
finding a new way to go in this new direction.
8.3 An Attack to BPCS Steganography Using
Complexity Histogram and Countermeasure
BPCS allows the replacement of nearly half of cover image in size with se-
cret data without any image degradation that can be perceived by humans.
Through several experiments, however, we have confirmed that the shape of
