Akhil Anjikar, Prashant Dahiwale and Suchita Tarare, Rajiv Gandhi college of Engineering & Research, India

Visual Cryptography is a special encryption technique that encrypts the secret image into n number of shares to hide information in images in such a way that it can be decrypted by the human visual system. It is imperceptible to reveal the secret information unless a certain number of shares (k) or more are superimposed. Simple visual cryptography is very insecure. Variable length key based visual cryptography for color image uses a variable length Symmetric Key based Visual Cryptographic Scheme for color images where a secret key is used to encrypt the image and division of the encrypted image is done using Random Number. Unless the secret key, the original image will not be decrypted. Here secret key ensures the security of image. This paper describes the overall process of above scheme. Encryption process encrypts the Original Image using variable length Symmetric Key, gives encrypted image. Share generation process divides the encrypted image into n number of shares using random number. Decryption process stacks k number of shares out of n to reconstruct encrypted image and uses the same key for decryption.

Visual Cryptography, Secret Sharing, Random Number, Symmetric Key.