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Improvement of steganographic robustness obtained by increase of depth of the used LSB layer is limited by perceptual transparency bound, which is the fourth LSB layer for the standard LSB coding algorithm and the capacity increases by embedding into deeper layer.
1. An intelligent algorithm will try to embed the message bits in the deeper layers of samples and alter other bits to decrease the error and if alteration is not possible for any samples it will ignore them.
2. Embedding the message bits in the same layer, it will easy to identify the secret message.
2.1.2 Steganographic Issues
Least signification bit (LSB) insertion is a simple approach for embedding information in the cover medium which provides having low robustness against attacks which try to reveal the hidden message .
Having low robustness against distortions with high average power  and against signal processing modifications .
LSB insertion scheme provides low security and vulnerable even to simple attacks .
The Random selection of samples used for embedding introduces low power Additive White Gaussian Noise (AWGN) .
Audio Steganography is more difficult than Video Steganography because Human Auditory System is more sensitive than Human Visual System .
Increasing the number of altered LSBs will induce noise .
Usage of less LSB's per sample will decrease the capacity and increase the transparency .
Accordingly, there are two following solutions for mentioned problems:
As with encryption, if one wants to communicate secretly with they must first agree on the method being used.Â
With encryption, Bit Selection and Sample Selection in Steganography improves the security of the Least Significant Bit modification Technique .
Another limitation is due to the size of the medium being used to hide the data. In order for steganography to be useful the message should be hidden without any major changes to the object it is being embedded in. This leaves limited room to embed a message without noticeably changing the original object.
The Secret message should be encrypted and then embedded. In case the steganography algorithm breaks, the use of encryption algorithm will make the encrypted secret message to be exposed to the intruder instead of the actual secret message [3, 4].
Â 2.2 Proposed System
The proposed system provides the center of attention on incorporation of two methods for securing global cyber data. To achieve this perfect blend, SBM Cipher is performed in which the cyber data is converted to cipher text and is embedded by bit replacement in audio signal with cipher bits by adopting AMET in the original bits of the audio are replaced by the message bits. This bit replacement is possible even in the deeper layers of LSB based on the values of the adjacent bits. This multilevel cladding ensures high level security and robustness to the global cyber data.
2.2.1 SBM Cipher
The idea of SBM Cipher is derived from a classic cryptographic technique called Homomorphic Encryption which involves in the mathematical operations within the Cipher data [5-homomorphic]. The basic mechanism behind the Homomorphic Encryption is performing the mathematical operations such as addition and multiplication of a secret message with the function aware to the one who encrypts the message. SBM Cipher penetrates its accuracy in converting the plain text into a cipher text with larger efficiency than that of its parent technique. In this technique, variety of cladding is performed over the cyber data. The levels are as follows.
1st Level - Varying Alphabet factor Length
This layer mainly focuses on providing an alternate alphabet for the alphabet present in the original message. Here the alphabet is varied in a sequence depending upon the factor value. By performing varying alphabet factor method the process of converting the plain text into the corresponding cipher text can be easily formulated.
2nd Level - Polybius Square Transformation
The next level of security is formulated by finding the position of appropriate letter (row and column value) in the 5*5 matrix with a letter which has been converted previously from the plain text into the cipher text. In order to increase the security, the values of the row and column is randomized. After the identification process is carried out, the position of the letter is found and their corresponding value is taken.
3rd Level - Bifid Cipher Encipherment
The values obtained from the Polybius Square Transformation is alternatively increased and decreased. Each letter in the cipher text provides two values either as row-column value or as column-row value. This value is alternatively increased-decreased or decreased-increased and the resultant is the cipher numbers. The swapping is a simple and also a powerful technique which can be efficiently used, so that the cryptanalysis can be made more difficult.
4th Level - Matrix Operation
The obtained cipher value is arranged into a Square matrix with the value 1 if there is any deficiency in any positions. The matrix thus formed is multiplied with the key matrix either after or before it is inverted. Without the key matrix the decryption of the cyber data is not possible at all. Hence, only the encrypter can be able to give the Cipher data for the decrypting the message from the audio.
2.2.2 Advanced Shuffled Embedded Technique (ASET):
The secret messages are embedded in the deeper layers with shuffling for achieving the high robustness against premeditated and unpremeditated attacks. When the cyber data bits are embedded into the deeper layers of LSB, it will induce the quantization noise . To reduce the quantization noise, the remaining bits are modified. The most significant feature of this system is embedding the message into the deeper layers of the LSB layers based on the values of adjacent message bits.. There are two inputs to AMET namely original audio sequence and cyber data sequence. These two inputs are converted to binary sequences and then given to AMET. Then the secret messages are embedded into original audio sequence by shuffling the layers. The embedded audio sequences are compared with original audio stream to reduce the noise, for that remaining bits are modified. In decoding, the secret messages are separated from the embedded audio stream. The secret messages will be in binary form, it is then converted to text form. Finally, audio signal in binary form also converted to an analog signal. By using the quantization method, original audio signal and the decoded audio signal will not differ much.
This provides increased robustness and high security.
Improved confidentiality and deniability.
Useful in Defence, Internet security, Business information transaction.
The AMET pictures its characteristics feature of shuffling the bits starting from the LSB towards the deeper layer in a shuffled manner. The shuffling should be done in such a way that there will not be any change in the quality of the audio stream before and after the embedding process. Since, the steganalysis of the LSB of an audio is very much easier , deeper layers is opted by using the shuffled embedding. The added advantage of AMET is that the embedding is done from LSB and towards MSB in a shuffled manner, hence resulting in output audio signal which would be very tedious to identify the shuffled bits. Thereby making the steganalysis and breaking the nutshell job. By using SBM Cipher cryptographic approach the binary format is provided and then the AMET is used for embedding it in an audio signal in the deeper layer as steganographic method.
2.3 Feasibility Study
The feasibility study deals with the analysis of a system under various aspects in order to determine whether the system or product is feasible. This is done under a variety of considerations in order to evaluate the effectiveness of the system.
The proposed system is highly feasible under various horizons and it provides various types of feasibility such as Economic feasibility, Operational feasibility and technical feasibility. This enables the ease of implementation of the proposed system in a most efficient way.
2.3.1 Economical Feasibility
For any system if the predictable reimbursement equal or exceed the expected economy, the method implemented can be evaluated to be economically feasible. In economic feasibility, economy assistance examination is done in which predictable expenditure and reimbursement are evaluated. Economic analysis is used for appraising the efficiency of the implemented system.
In economic feasibility, the most significant isÂ economic-reimbursement analysis. As the name suggests, it is an investigation of the costs to be acquired in the scheme and benefits derivable out of the scheme.
The proposed system is economically feasible because the cost for development and implementation cost of this product is minimum. The programming language used here is java which is freely available in the internet. In addition the package used here is NetBeans which is also a freeware. Since this product requires minimum hardware and software requirements the economic feasibility increases to a greater extent.
2.3.2 Operational Feasibility
Operational feasibility is mainly concerned with defects like whether the method will be used if it is developed and executed. Whether there will be a conflict from users that will effects the probable application reimbursements? The important questions that help in testing the operational feasibility of a system are following.
Does administration sustain the project?
Are the users not cheerful with recent commerce practices? Will it decrease the time significantly? If yes, then they will provide salutation to the modification and the new system.
Have the customers been implicated in the scheduling and improvement of the project? Early participation decreases the probability of opposition towards the innovation scheme.
Will the projected method really provides advantage to the administration? Does the overall reaction raises? Will ease of understanding of information be vanished? Will the method consequence the clients in significant way?
The programming language used in the proposed system is java. Since java is platform independent, this product can be implemented irrespective of the platform. This paves the way for the operational feasibility of the proposed system. The front end used here are JSP and servlets which comes along with java. Since NetBeans provides a wonderful user friendly run time environment for java the feasibility in operation reaches its optimum height. The minimum software required for running the product is just a web browser which is available by default in most of the operating systems. The above factors increase the operational feasibility of the proposed system.
2.3.3 Technical Feasibility
In technical feasibility the following problems are taken into deliberation.
Whether the required technology is offered or not
Whether the required resources such as Software and hardware , Manpower- programmers, testers & debuggers are available.
Once the technical feasibility is recognized, it is important to consider the pecuniary issues also. Since it may come about that increasing a particular system may be technically probable but it may require massive savings and remuneration may be less. For appraising this, economic feasibility of the planned system is carried out.
The two major techniques used in our proposed system are AMET cipher and AMET which falls under Cryptography and Steganography respectively. The technical feasibility of the product lies in the hands of encryption and decryption techniques used here which is one of the major advantages of this system. Thus the above mentioned techniques enhance the technical feasibility of this product.