A Data Hiding Algorithm Using Steganography

Topics: Cryptography, Bit, RSA Pages: 7 (1925 words) Published: May 12, 2013
A Data Hiding Algorithm Using Steganography
Ramya Ramanath
Vibha Valsan

RVCE
Bangalore

Abstract- This paper discusses the design of a data hiding algorithm using steganography. Steganography is the art and science of writing hidden messages using images in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message. Steganalysis is the method used by attackers to determine if images have hidden data and to recover that data. By matching data to an image, there is less chance of an attacker being able to use steganalysis to recover the data. Before hiding the data in an image the paper first encrypts it. The binary code of the data is first collected using the code explained. There can be many ways in which the message can be encrypted. The last bit of each byte in the binary code of the image can be changed to contain the message. Changing the last bit would not usually affect the image to a great extent. We can embed the message either directly in order or in random or in a reverse manner where the first few bits express how it is hidden. The steganography method proposed in this paper and illustrated by the paper is superior to that used by current steganography tools.

Keywords- Steganography, steganalysis, data hiding, algorithm Introduction
Steganography is the process of hiding a secret message within another message. Steganography can be an invaluable tool in maintaining confidentiality, which is one of the three policies computer security is concerned with, along with integrity and availability. [1] The importance of steganography lies in the fact that it hides the very existence of the secret it is protecting. Attackers are threats because they attempt to damage or gain access to assets by taking advantage of these asset’s vulnerabilities. Steganography makes the job of the attacker more difficult because the very existence of the asset is hidden. With cryptography the attackers are better able to break encryption algorithms and these capabilities will only increase in the future. [2] DES,RSA,WEP,AES are examples of some encryption algorithms that were thought to be secure at the time of their design and cannot be misused, but were broken in the future when attackers had more powerful computational resources. The examples prove that encryption is not enough to stop attackers from gaining access to confidential information. Steganography must also be employed to protect confidential assets from being compromised by attackers because there is no clue about the existence of data. [3] Since the data’s presence is not known attackers do not bother to find ways to misuse them.

Steganography papers that hide data in images generally use a variation of least significant bit (LSB) embedding. In LSB embedding, the data is hidden in the least significant bit of each byte in the image. The size of each pixel depends on the format of the image and normally ranges from 1 byte to 3 bytes. [4]Each unique numerical pixel value corresponds to a colour; thus, an 8-bit pixel is capable of displaying 256 different colours. Given two identical images, if the least significant bits of the pixels in one image are changed, then the two images still look identical to the human eye . This is because the human eye is not sensitive enough to notice the difference in colour between pixels that are different by 1 unit . Thus, steganography algorithms use LSB embedding because attackers do not notice anything odd or suspicious about an image if its pixel’s least significant bits are modified . [5] Steganalysis is a process where attackers analyze an image to determine whether it has hidden data in it. A common steganalysis approach is to graph the pixel values of an image that is suspected of containing hidden data. Statistical analysis is then performed on the graphed pixel values [6]. The attackers hope to find anomalies in the statistical analysis of these images. These...