TECHNOLOGY Blowfish Encryption Using Key Secured Block Based Transformation
Nitin B. Sambre · 2014
Encryption is a process of converting a one form of information in another form which is hard to understand .Now a days, a large amount of informati on get transfer with wired or wireless network. Inf ormation contents may be textual data or image data. Therefo re encryption of text or image is most important du ring secure transmission of information. Images are widely used in several processes like military field, medical imaging, video conferencing where confidentiality about image info rmation is very important. As we know, pixels in pl ain image are strongly correlated. Image information get perc eive due to this high correlation. Most of availabl e image encryption algorithms are used for encryption of pi xel information only but key secured block based tr ansformation technique change the position of pixels and provide low correlation among image pixels so that less am ount of information get perceived . The block transformati on algorithm divides the image in to no. of blocks and shuffles their position of blocks to decrease the Correlatio n and increase its entropy value. Divide an image i n more no. of blocks gives the more security of image. Transforma tion table will decide new positions of blocks. The aim of Key secured block transformation is to enhance the sec urity of an image. Here, key provide a security for transformation table .Different keys generated for different types of image so ,if input image data changed automatic ally key will also get change. Here key is used for two purposes, one for to build transformation table and second t o encrypt image data. So as key changed, transformation table will also get change and image get transformed wit h this new transformation table. Block Transformed image is th en passed for encryption process. Here we used Blowfish image encryption algorithm because of variable and longes t key size. At the receiver side these blocks are r etransformed in to their original position and performed a decrypti on process which gives the original image.