26-10-2016, 02:09 PM
1461357478-IEEEpaper1461354178046.docx (Size: 222.7 KB / Downloads: 5)
Abstract: To increase the security of messages sent over the internet steganography is used. In this paper we have discussed the technique Reed Solomon Encoder for encrypting and decrypting the text and LSB(least significant bit) for hiding and retrieving the data hided in an image.
Keywords: Steganography, LSB(least significant bit), Reed Soloman Encoder.
Introduction: steganography is derived from the Greek words stegos meaning cover and grafia meaning writing defining it as covered writing.Past: Steganography technically means covered or hidden writing. Its ancient origins can be traced back to 440 BC.
Steganography is the art and science of secret communication. The original files can be referred to as cover text, cover image, or cover audio. After inserting the secret message it is referred to as stego-medium. A stego-key is used for hiding/encoding process to restrict detection or extraction of the embedded data.Steganography is one of the most powerful techniques to conceal the existence of hidden secret data inside a cover object.
The goal of Steganography is to avoid drawing suspicion to the existence of a hidden message. This approach of information hiding technique has recently become popular in a number of application areas. Digital audio, video, and images are increasingly furnished with distinguishing but imperceptible marks, which may contain a hidden copyright notice or serial number or even help to prevent unauthorized copying directly.
Modern steganography uses the opportunity of hiding information into digital multimedia files and also at the network packet level. Hiding information into a medium requires following elements.
1. The cover medium© that will hold the secret message.
2. The secret message (M), may be plain text, digital image file or any type of data.
3. The stegonographic techniques
4. A stego-key (K) may be used to hide and unhide the message. In modern approach, depending on the cover medium, steganography can be divided into five types:
a. Text Steganography
b. Image Steganography
c. Audio Steganography
d. Video Steganography .
e. Protocol Steganography.
• Image steganography: Images are used as the popular cover medium for steganography. A message is embedded in a digital image using an embedding algorithm, using the secret key. The resulting stego-image is send to the receiver. On the other side, it is processed by the extraction algorithm
The spatial domain techniques manipulate the cover-image pixel bit values to embed the secret information. The secret bits are written directly to the cover image pixel bytes. Consequently, the spatial domain techniques are simple and easy to implement.
Least significant bit (LSB) technique is the first and simplest technique that was used to embed secret messages into cover file. In LSB Method the cover and secret message are converted into streams of bits and then later the secret message is embedded into the cover by replacing the LSB bit of the cover with one or more bit of the secret massage and then sent to receiver. In order for the receiver to extract secret massage the receiver accesses the sequence of sample indices used in the embedding process.The Least Significant Bit (LSB) is one of the main techniques in spatial domain image. using the same key. During the transmission of stego- image unauthenticated persons can only notice the transmission of an image but cannot see the existence of the hidden message.
REED SOLOMON ENCODER ALGORITHM:
Reed–Solomon codes are an important group of error-correcting codes that were introduced by Irving S. Reed and Gustave Solomon in 1960.Reed-Solomon codes are block-based error correcting codes with a wide range of applications in digital communications and storage. Reed-Solomon codes are used to correct errors in many systems such as Storage devices,Wireless or mobile communications,Satellite communications,Digital television / DVB ,High-speed modems such as ADSL, xDSL, etc.
Reed Solomon Encoder Code:
message=input('secret meassage:', 's');
password=input('password:' , 's');
opp=input('decrypt(-1) or encrypt(1):');
password=password-97;
[notused size_of_message]=size(message);
[notused size_of_password]=size(password);
pos=1;
output=[];
for i=1ize_of_message
output(i)=message(i)+ password(pos).*opp;
pos=pos+1;
if(pos>size_of_password);
pos=1;
end
end
enc = fec.rsenc
out=sprintf('>%s<' ,output);
disp(out)
LSB Algorithm:
A. Sender Side : The proposed scheme uses RSA or Diffie Hellman algorithm to encrypt secret information. To provide higher security the secret information is encrypted first and encrypted ASCII value is converted in binary form. The image pixels at the same time are also converted into binary form. The image is now used as a cover to embed the encrypted information. This process is done by LSB encoder which replaces the least significant bit of pixel values with the encrypted information bits. The modified picture is now termed as Stego image.
B Receiver Side : Upon reception of Stego image the receiver firstly converts the pixels into their corresponding binary values. The LSB decoder then detaches the encrypted data from image pixel values. The encrypted data is decrypted using decryption algorithms. This is how, the plain text is recovered from image. Fig. 2 shows the whole process at the receiver side.
CONCLUSION: This paper is a short introduction to the world of steganography. We have shown how the simplest methods work and how they can be explored. We have used Reed solomon encryption algorithm to provide more security. If a message is encrypted and hidden with a LSB steganographic method the embedding capacity increases and thus we can hide large volume of data. of the statistical framework in order to prove its efficiency and also to show its level of security. The main focus of the paper is to develop a system with extra security features where a meaningful piece of text message can be hidden by combining two basic data hiding techniques. The method can further be extended with taking into account other data hiding and encryption techniques. Every technique leaves some space for further improvement. The method can further be extended with taking into account other data hiding and encryption techniques.