A MODIFIED METHOD OF INFORMATION HIDING BASED ON HYBRID CRYPTOGRAPHY AND STEGANOGRAPHY
Fadhil Salman Abed · International Conference on Digital Information Processing and Communications · 2013
“Combination of cryptography and Steganography for secure communication” is an application, which combines both Cryptography methods (i.e. Encryption, decryption) and Steganography techniques to make the communication more secure. The outcome of this project is to create a cross-platform tool that can effectively hide a message (i.e. Word document) inside a image file. It is concerned with embedding information in a secure and robust manner. In embedding stage, the colour of the cover image is separated to its component (RGB) then all are partitioned into non-overlapped blocks using quad-tree partition that is called range, and down sampling the range images to quarter its size to generate the domain. The domain pool is partitioned in to over-lapped blocks. To find the best range-domain match, the linear affine mapping applied to represent the blocks of domain in terms of range blocks using IFS-code. The obtained values of the IFS coefficients the scale (s) and offset (o) are used for the embedding process. The characters value of the secret message are taken as an ASCII, after keeping 2 digits of the fraction part of (s) and (o) values and removing the other digits. The secret message will be added to the fraction value in order to occupy the 3rd, 4th and 5th places after the decimal point without affecting the 1st and 2nd places of the original fraction and without degrading the image quality. The proposed system depends upon preparing the image data for the next step fractal compression through steganographic process and using two levels of security: the hybrid RSA with Knapsack algorithm, A hybrid of RSA and knapsack cryptosystem can be represented as a secure system. The results that achieved from using this technique is the encrypted message which acquires a higher security and accuracy when compared with RSA and knapsack cryptosystem individually in modern communication systems to protect the information transmitted over an insecure communication channel.