Veena Venkitesh1Department ofComputer Science and Engineering, Adi Shankara Institute of Engineering andTechnologyEmail: [email protected] Divya D1Department ofComputer Science and Engineering, Adi Shankara Institute of Engineering andTechnology Email: divya.
[email protected]—Information security has become a vital part in mostorganizations. The main reason for this is that access to information and theassociated resources has become easier because of the developments indistributed processing, for example the Internet and electronic commerce.
Theresult is that organizations need to ensure that their information is properlyprotected and that they maintain a high level of information security. In manycases, organizations demand some proof of adequate information security frombusiness partners before electronic commerce can commence.In today’s information age,information sharing and transfer has increased exponentially. The threat of anintruder accessing secret information has been an ever existing concern for thedata communication experts. Cryptography and steganography are the most widelyused techniques to overcome this threat.
This paper discusses a basic approachto enhance data security.Keywords-Cryptography; Security;Encryption; I. INTRODUCTIONInthe world today, there is a rapid increase in the number of internet users. Arecent statistics shows that there are 3.5 billion people who use internet.
Within a year, there has been a tremendous increase in the internet users toover a billion. Due to the increase in the internet for commercial andnoncommercial purposes, there is an increased need for security of data that istransferred or exchanged. Therefore,it is the necessary application of reliable data security techniques for dataexchange via internet media. Cryptography and Steganography are two of the mostcommonly used to secure digital data.
Cryptography is a technique for securingdata where the original data is randomized in such a way that it is difficultto understand. Original data can only be opened by a specific person using predefinedcustom keys.II.
VISUAL CRYPTOGRAPHY AND STEGANOGRAPHYVisualCryptography is a special encryption technique to hide information in images insuch a way that it can be decrypted by the human vision if the correct keyimage is used. The original information that is to be encrypted is known assecret. Once the encryption is completed, ciphers are generated which is knownas shares.
The part of secret in twisted form is known as share. To share thesecret among group of n participants is the fundamental idea behind visual cryptography. Thesecret is divided into n number of pieces, referred as shares, in order toshare the secret.
After that, these shares are distributed among nparticipants. Each participant provides his own share, to reveal the originalsecret. There are many visual cryptographic schemes are available, but thebasic scheme is 2out of 2visual cryptography. In this scheme secret image isdivided in to exactly two shares, if both two shares are superimposed thensecret will be revealed. In (k, n) visual cryptographic scheme secret image isdivided into n shares; if k or more then k shares are superimposed then secret will be decoded. The (n, n) visualcryptographic scheme is extended version of (k, n) visual cryptographic scheme.
In (n, n) visual cryptographic scheme all n shares are require to decryptsecret while revealing the secret. Figure 1 shows 2 out of 2 VisualCryptography shares. Figure 1: 2 out of 2 VC schemeSteganography is the technique of writing secret orconfidential messages in a way such that no one but only the intended receiverknows of the existence of the information; this is in contradictory tocryptography, where the existence of the message itself is not disguised, butthe content is obscured. Steganography clearly means covered or hidden writingor information passed with secrecy. Usually, a steganographic message will beshown to be something else: a picture, an article, or some other information -the cover text. Steganography is always chosen over cryptography because themessages do not attract attention to themselves but to messengers Figure 2 showsa basic Steganography framework.
Figure 2: Steganography Framework In anunaltered Steganography framework, the mechanism for embedding the message isunknown to Wendy and shared as a secret message between Alice and Bob. III. RELATED WORKHere we are combining both visual cryptographyand steganography technique for enhancing data security. The implementation of Steganographyin blend with visual cryptography is a powerful model and adds a lot ofchallenges to identifying such hidden and encrypted data. Basically, a usercould have a secret image with the secret data which could be split up into arange of encrypted shares.
Finally when such encrypted shares are reassembledor decrypted to restore the real image it is possible for one to have anexposed image which yet consists of the secret data.IV. PROPOSED TECHNIQUEAlgorithm for steganography:-Thefunction used in this cryptosystem should have a bijective mapping i.e.
thefunction should have one-one and onto mapping. This indicates the inverse ofthe function exists. Hence the original information ofthe image can be retrieved back during decryption without any error.
Thefunction is given as: Encryption :-Step 1: Ask for theimage and the keys X1 and Y1 and the resizing factor “fac”.Step 2: Generate the function g( ) which will contain the valuesgenerated from a function in an array.Step 3: Find the absolute value of the function g( ). Here U=GCD(X1,Y1).Step 4: Pass it through a low pass filter.Step 5: Resize the image using bi-cubic interpolation and get theRGB layer in a separate matrix with the factor “fac”.
Step 6: Multiply the pixel values with the absolute valuescalculated.Step 7: Flip the new formed Red matrix upside-down.Step 8: Flip the new formed Green matrix left-side right.Step 9: Rotate the Blue matrix by twice of the “fac”.Step 10: Generate the image again save it in .
bmp format. (Theimage is saved in .bmp format because actual values of the pixel are retainedand the number of pixels is also the same which is in contrast with the othercompressed images like jpeg, gif, etc.)Step 11: Send the image with the resizing factor to the receiver.Decryptionis just the reverse process of encryption. The aim of decryption is to make theencrypted information readable again (i.
e. to make it unencrypted).Step 1: Receive the image and ask for the key and resizing factor.
Step 2: Break the received image into Red Green and Blueparts/layers.Step 3: Flip the new formed Red matrix upside-down.Step 4: Flip the new formed Green matrix left-side right.
Step 5: Rotate the Blue matrix by twice of the “fac”.Step 6: Generate the function depending upon the keys. Here U=GCD(X1,Y1).Step 7: Find the absolute value of function and pass it throughlow pass filter.Step 8: Divide the pixel values of the received image with theabsolute value of the function.
Step 9: Form the image.Step 10: Resize the image by multiplying its rows and column withthe “fac” using bi-cubic interpolation.V.
RESULTSHere, we are analyzing the results of proposed and existing techniquesand we found that proposed technique can play important role in concerned area.Table 1 shows the comparison between existing and proposed techniques. Table 1: Comparison between existing and proposed techniques Parameters Existing Technique Proposed Technique Security Human Vision Time Confidentiality Efficiency Low Predictable Medium Low Medium High Unpredictable Low High High Durability against damage Not Retrievable Reading upto 30% damage V. CONCLUSIONSteganography and visual cryptography have many similaritiesand differences, and thus have various uses in the digital and real worlds.
Different algorithms for steganography and visual cryptography have differentadvantages and power, as well as disadvantages and weaknesses. So we noticethat certain methods are easier to detect than others. But generally, the jobof forensic and security investigators is not easy. When steganography andvisual cryptography detection tools are used exclusively, it is almostimpossible for investigators to uncover hidden or encrypted data. On thecontrary, if these detection tools or softwares are used in connection withother tools and parameters that reduce the search to a smaller data set, thenit makes the lives of investigators much easier and provides them a betterchance of detecting the suspicious data. It is always surprising to learn howdetectable a data is after applying visual cryptography with perfect restorationto an image with secret data.
Also, an interesting detection question iswhether we can reconstruct a set of ‘n’ shares into a meaningful image that isdifferent thanthe image used to create those shares by omitting some of the noriginal shares and by including an additional share specifically constructedfor such purpose. Basically this is a question about the uniqueness of theshares created by different visual cryptography algorithms. WhenVisual Cryptographyis used with Steganography it makes the task difficult todecrypt the secret message. This makes the system a highly secure, durable andefficient in information protection.
Our future work is to provide the securityby using latest cryptographic algorithm and research for further improvementsto carry out so that we could come up with new ideas which will be beneficialfor the society. VI. REFERENCES1 https://www.ukessays.com/essays/computer-science/steganography-and-visual-cryptography-in-computer-forensics-computer-science-essay.
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