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QUALITATIVE SPATIAL IMAGE DATA HIDING FOR SECURE DATA TRANSMISSION
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Introduction
Steganography comes from the Greek word which literally means, "Covered or secret
writing".Steganography's intent is to hide the existence of the message.
1.1 Need
The goal of Steganography is to hide messages inside other "harmless" messages in a way
that does not allow any "enemy" to even detect that there is a second secret message
present. The only missing information for the "enemy" is the short easily exchangeable
random number sequence, the secret key, without the secret key, the "enemy" should not
have the slightest chance of even becoming suspicious that on an observed communica-
tion channel, hidden communication might take place.
With the development of network technology, many information can rapidly be
transmitted to everywhere through it, which can save much time and money of peo-
ple.Each person can also nd their information that they want on the Internet. However,
due to the fact that digital information can be corrupted and stolen easily, security
of protecting information has become a very important topic in recent years.Humans
have continually sought new ecient and secret ways to protect condential informa-
tion. While electronic communication becoming widely accepted as the primary means
of communication, information security and privacy are becoming a growing concern.
Many methods have been proposed for protecting the security of digital information,
including information hiding and cryptography. Information hiding is to conceal some
information into digital media by modifying its content so that the information can't
be seen.Within the computer networks, condential information may be found in two
states; stored or transmitted through the network. During data exchange, it is a basic
request that only the intended recipient has the ability to decipher the contents of the
transmitted data.
A common solution to this problem is the use of encryption to obscure the in-
formation content of the message. While encryption masks the meaning of the data,
instances exist where it is preferred that the entire transmission process is not evident to
any observer that is, even the fact that transmission is taking place is a secret. In this
case, the transmission process itself should be hidden.
Basic concept
Information Hiding (Steganographic) techniques are thus used to hide or cover the exis-
tence of transmitted data with other data, intuitively referred to as cover data. Informa-
tion hiding has focused on carriers like images and audio les. It is mostly used when a
sender wants to convey information to a recipient but does not want anyone else to know
that the two parties are communicating.
Many previous research eorts were concentrated in information hiding area on
developing new techniques for hiding messages rather than enciphering them because hid-
den messages arouse less suspicion. So, the study of communications security includes
not just the encryption of messages but also the trac of messages security whose essence
lies in hiding information techniques.To make the communication more secure, the secret
information can be compressed and encrypted before it is hidden in the carrier. In this
way the amount of information that is to be sent is minimized, and it is also easier to
hide a random looking message into the carrier than to hide a message with a higher
Introduction
degree of regularity. Encrypting the compressed message before hiding is recommended
to provide double protection.
It seems natural to use digital images , video, or audio for hiding secret mes-
sages. Most of information hiding algorithms are based on the gaps in human visual and
audio systems, that means modifying the least signicant bits (LSB) of gray levels in
digital images or sound tracks. Additionally, bits of information can also be inserted into
coecients of image transforms, such as discrete cosine transform, (DCT), and discrete
wavelet transform (DWT). Transform based techniques typically provide higher image
delity and are much more robust to image manipulation. Thus, if an embedded signal
to be robust.
Information hiding fall into two general categories based on the embedding (steganog-
raphy) and detection techniques (steganalysis). The main objective of rst category is to
increase the payload, studying the properties of the stego-image before and after embed-
ding process, and improving the robustness. Cryptography is to conceal the existence of
secret information by scrambling them into unrecognized message so that the information
can't be understood. The common characteristic between information hiding and cryp-
tography methods is that only the authorized person can reveal the precise information.
Hence, the best way is to combine the information hiding and cryptography methods
for protecting the security of secret information. Information hiding and cryptography
schemes have been proposed to protect the content of digital media.
Applications
1) It is used for copyright protection, content labeling and hidden annotations.
2)It is also used for authentication and integrity verication secure communica-
tion (steganography)
3) Data hiding techniques operate in two existing domains, spatial domain and
Frequency domain. Almost all spatial domain techniques are used for data Hiding ap-
plications. That require high payload and invisibility.In this domain, The images are
divided into number of bit planes (usually eight) and use the rst nth planes for embed-
ding data since the noise in these planes are high.
4) Frequency domain techniques are mainly used for digital watermarking, n-
gerprinting, authentication, copy control, tamper detection, integrity and ownership ver-
ication, self-correcting, and nally, broadcast monitoring
5) Data hiding technique mainly used for security, protection purpose.