Cryptography Reference
In-Depth Information
Fig. 8.4.
Web-based confidential communication.
BMP or PNG image by BPCS method. But if the message is not so large,
using a JPEG image may be better because JPG looks more innocuous than
BMP to the third party.
8.2.2 Forgery Detective Digital Certificate System
This application makes use of the fragility of the embedded data in BPCS
steganography. Also, a large embedding capacity plays a key role.
Currently, a certification document is written or printed on a paper
surface or on a plastic card surface. No computer data can serve as a certificate
document by itself. This is because all computer data today have a single-
layered information structure in the sense that all information is just as it
looks. Computer data are always alterable, and it is impossible to tell whether
the given computer data is original or not just by looking. A PDF file is
not very easy to alter, but is still editable. Therefore, a digital document is
forgeable. It is impossible to decide if it is authentic or counterfeit. This is
the reason why we cannot e-mail a digital certification document over the
Internet. Currently, a digital signature system is available to make a digital
document formally authentic. However, it is based on an extra information-
infrastructure, namely, the human authentication bureau. But it is not very
handy for our daily use. Therefore, a digital certification system using no extra
frameworks, if invented, is very evolutionary. The following is one of such.
