Visual Cryptography

Visual cryptography is a creative technique of sharing secrets. The key idea behind visual cryptography is to encrypt the original secret image into number of shares. The individual share does not reveal the original secret image until two or more shares overlapped. The image is composed of white and black pixels. Visual cryptography provides information security by encrypting the visual information in such a manner that decryption can be done by manual perception system. There is no need of any cryptographic algorithm for decryption in visual cryptography. Performance of visual cryptography mainly depends on the pixel expansion and contrast. This paper put lights on the following sections:

• What is VCS model?

• Visual cryptography schemes

• Security issues

• Prevention methods

• Visual cryptography with steganography