Abstract:
This dissertation endeavors at evolving portentous novel secure steganographic bit
embedding schemes for digital ASCII text document besides suggesting enhancement in
some existing text-centric steganographic methods. Further, a cover generation algorithm for
the said purpose is also conferred. Our proposed algorithms uses substitution technique for
embedding / hiding secret message bits inside the text-cover whereas our cover generation
algorithm exploits statistical characteristics of randomly generated data for data hiding
purpose.
To contrast our proposed schemes with prevalent schemes we have quantified the test results
using Hamming distance, Levenshtein metric (also called edit distance) and Jaro-Winkler
distance, where to elaborate on the quality of quantified results we have plotted probability
distribution of Cover and Stego (Text) Object for visual analysis. Security of prevailing and
newly proposed Steganographic schemes is gauged using “Known Cover and Known
Message Attacks” where “Chosen Message Attack” instantly reveals the logic behind
prevalent Steganographic schemes. Our experimental results are in confirmation with
generally accepted evaluation metrics for gauging Steganographic Systems. Moreover, our
suggested bit embedding methods does not increase or decrease the size of original Cover file
but yet increases its bit embedding capacity. Also, saving the Stego Object in Portable
Document Format (.pdf), and / or MS Word (.doc) file (including Notepad) and its retrieval
thereafter does not suffer from any information loss. The advantage of our proposed Cover
(as fake cryptogram groups) generation method is that the Stego Object can be transmitted in
printed form without requiring a code book for bit extraction at receiving end.
