A New Approach for Multilevel Steganography Using Visual Cryptography for Multimedia Application”

Abstract

Cryptography and steganography are the two popular methods available to provide security. Cryptography and steganography when used individually provides security but when combined provides higher level of security. Visual cryptography is a cryptographic technique which allows visual information to be encrypted in such a way that decryption. Steganography is an art of hiding the existence of secret information by embedding it in a cover and hence preventing the unauthorized access of confidential information. Secret data may be text message, audio, image or video. This is implemented by including three phases namely, Encryption, Steganography and VC, at the transmitter side. In the first phase the secret message is encrypted in to a cipher text using XOR operation. The second phase is used to hide the cipher dynamically in an image by changing the number of bits hidden in RGB channels based on the indicator value. In the final phase the stego image created in the second phase is hidden in four shares created from a secret image using VC. The secret image, stego image and the hidden messages can be recovered from the shares without involving any complex computation. The encrypted secret message is embedded into an image, which is then embedded inside the shares thereby fully safeguarding the inbuilt-secret message. By increasing the number of shares we can store more number of stego images thereby the amount of secret data transmitted across the network increases multifold. The secret images used to hide stego image can be revealed by combining the shares using OR operation. The stego images, cipher and the plain text can be retrieved by extraction process. The proposed algorithm takes the advantage of all these techniques discussed above thereby increasing the reliability and secrecy of the multimedia information transmitted. This is implemented by including three phases namely, Encryption, Steganography and Visual Cryptography (VC), at the transmitter side.