Image Encryption Using Block-Based Transformation Algorithm

Encryption is used to securely transmit data in open networks. Most of the available encryption algorithms are mainly used for textual data and may not be suitable for multimedia data such as images. In this paper, we introduce a block-based transformation algorithm based on the combination of image transformation and a well known encryption and decryption algorithm called Blowfish. The original image was divided into blocks, which were rearranged into a transformed image using a transformation algorithm, and then the transformed image was encrypted using the Blowfish algorithm. The results showed that the correlation between image elements was significantly decreased by using the proposed technique. The results alsoshow that increasing the number of blocks by using smallerblock sizes resulted in a lower correlation and higher entropy.