Due to growth of multimedia application, security becomes an important issue of communication and storage of images.Encryption is one of the ways to ensure high securityImages are used in many fields such as medical science, military; they are stored or transfer through network, security of such image data is important.This work proposes a novel scheme for the security of such images by the method of separable reversible data hiding in encrypted images. In the first phase, a content owner encrypts the original uncompressed image using an encryption key. Then, a data-hider may compress the least significant bits of the encrypted imageusing a data-hiding key to create a sparse space to ...view middle of the document...
Basically it is used so that the content stays secure and is not manipulated when its being transferred.
Types of Cryptography:
There are two main types of cryptography:
• Secret key cryptography
• Public key cryptography
Secret key cryptography is also known as symmetric key cryptography. With this type of cryptography, both the sender and the receiver know the same secret code, called the key. Messages are encrypted by the sender using the key and decrypted by the receiver using the same key.
Public key cryptography, also called asymmetric key cryptography, uses a pair of keys for encryption and decryption. With public key cryptography, keys work in pairs of matched public and private keys.
The existing methodology is that of non-separable reversible process.Its a serial process as shown the diagram below.
Here in the first stage the image is encrypted with the help of an encryption key. In the second stage the additional data is added with the help of a data hiding key.
Now on the receiver side the image has to be decrypted first now then it is possible to remove thebhidden data. The user who is interested in only the data must be in possesion with both the keys as the image has to be decrypted with the help of the encryption key then the data can be obtained with the help of the data hiding key.
The user has to go through these phases irrespective of what he wants only the image or the data or both.
There are also a number of works on data hiding in the encrypted domain. In a buyer–seller watermarking protocol [P. Bas and F. Cayre, “Natural watermarking: A secure spread spectrumtechnique for woa,” in Proc. 8th Inf. Hiding Workshop (IH 2006), LectureNotes in Computer Science, Springer-Verlag, Alexandria, VA, Jul.2006, vol. 4437, pp. 1–14.], the seller of digitalmultimedia product encrypts the original data using a public key,and then permutes and embeds an encrypted fingerprint provided bythe buyer in the encrypted domain. After decryption with a private key,the buyer can obtain a watermarked product. This protocol ensuresthat the seller cannot know the buyer’s watermarked version whilethe buyer cannot know the original version.
This paper proposes a novel scheme for separable reversible data hiding in encrypted image. In the proposed scheme, the original imageis encrypted using an encryption key and the additional data are embeddedinto the encrypted image using a data-hiding key. With an encryptedimage containing additional data, if the receiver has only thedata-hiding key, he can extract the additional data though he does notknow the image content. If he has only the encryption key, he can decrypt the received data to obtain an image similar to the original one,but cannot extract the embedded additional data. If the receiver has boththe data-hiding key and the encryption key, he can extract the additionaldata and recover the original image without any error when the amountof additional data is not too large.
Proposed Scheme :-