Cryptography Reference
In-Depth Information
E) There are many variations in implementing a BPCS steganography pro-
gram. Such variation can be put into an embedding/extraction key. This
key is neither included in the program, nor hidden in the vessel image.
8.2 Possible Application Systems of BPCS
Steganography
Possible applications of BPCS steganography are categorized into several
groups according to its property. The most important properties of BPCS
are,
(A) very high embedding capacity,
(B) secure confidentiality of the embedded information,
(C) fragility of the embedded information,
(D) vessel image and embedded data can not be separated in the embedded
vessel image. An embedded vessel image is called stego image.
So, we can categorize the applications in reference to those properties. In
the following we will explain three specific applications. The first one is with
property (A) and (B), the second one makes use of (C), and the last one owes
to property (D). Some application can make use of other steganography than
BPCS. We will mention it accordingly.
8.2.1 Web-Based Communication
A web-based confidential corresponding method by BPCS steganography is
the most unprecedented realization of secret communication channel. It is the
most hard-to-detect communication method. Fig. 8.4 illustrates the scheme,
where A and B are two persons having a respective home-pages on the
Internet. The communication steps are as follows. They have a common key
to embed in and extract from the message.
Step-1: A and B decide which key to use
Step-2: A embeds his secret message, that is addressed for B, in As image to
make it a stego image
Step-3: A uploads the stego image on As home-page
Step-4: B downloads the image and extracts the message by using the common
key and read the message
Step-5: B embeds his reply-message in Bs image
Step-6: B uploads the image on Bs home-page
Step-7: A downloads the image and extracts the reply-message to read the
reply-message
In this communication scheme, it is extremely di
cult for the third party
to check the secret communication. This scheme can be implemented by using
