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S Reddy Jyoteeswara Prasad and R V S Sathyanarayana
S V University College of Engineering, Tirupati, Andhra Pradesh, India.

Abstract—This paper introduces a new concept for image encryption using binary key images. Here the original 2D (Grayscale image) or 3D (Color) image is encrypted with 2D or 3D key images (keyimage is either color or a grayscale image). A binary image is introduced as a “keyimage” with the same size as the original image to be encrypted. We also introduce two image encryption algorithms using this key-image. One is called the BitplaneCrypt algorithm, while the other is named as the EdgemapCrypt algorithm. Both of them can fully encrypt 2D and 3D images such as grayscale images, color images and medical images. The key image is either a Bitplane or Edgemap generated from the image, both algorithms is to change image pixel values by performing the XOR operation between the key-image and each bit plane of the original image. This is followed by an image scrambling process which changes the locations of image pixels or blocks. All edge detectors with any specified threshold value can be used to create the edge map as a key-image for the EdgemapCrypt algorithm. Any existing image scrambling method can be applied to these two presented algorithms. Experiments have demonstrated that both algorithms can fully encrypt the 2D and 3D images. The original 2D and 3D images can also be completely reconstructed without any distortion. Cryptanalysis has shown that the algorithms have extremely large security key space and can withstand most common attacks such as the brute force attack, cipher attacks and plaintext attacks. All these ensure the images can be protected with a higher security level. The presented algorithms are easy to implement in hardware because they operate at the binary levels. They are also suitable for multimedia protection in real-time applications such as wireless networks and mobile phone services.

Index Terms—Loss less image encryption, Key-image, Edge map, Plaintext attack, Brute force attack, Ciphertext attack

Cite: S Reddy Jyoteeswara Prasad and R V S Sathyanarayana, "IMAGE ENCRYPTION USING COLOR KEY IMAGES," International Journal of Electrical and Electronic Engineering & Telecommunications, Vol. 2, No. 4, pp. 37-46, October 2013.