The term of hide information is the process of covering some private or secrete
data to make sure that there is no another party can disclose or altering it
(Al-Azawi and Fadhil, 2010). Under this topic we can
drive two techniques which are used to hide information one is the digital watermarking
this technique used for two main things the first is for authentication purpose
and the second is to demonstrate the intellectual property rights, the another
technique is the steganography which is used mainly for hiding information from
any unauthorized party, in this case the aim is to prevent the message being
detected by any other party (Kawaguchi and Eason, 1998;
Majeed et al., 2009).
Steganography and encryption are both used to ensure data confidentiality.
However, the main difference between them is that with encryption anybody can
see that both parties are communicating in secret. Steganography hides the existence
of a secret message and in the best case nobody can see that both parties are
communicating in secret. This makes steganography suitable for some tasks for
which encryption are not, such as copyright marking. Adding encrypted copyright
information to a file could be easy to remove but embedding it within the contents
of the file itself can prevent it being easily identified and removed. The formal
definition for the steganography is the art and science of communicating in
such a way that the presence of a message cannot be detected. Simple steganographic
techniques have been in use for hundreds of years, but with the increasing use
of files in an electronic format new techniques for information hiding have
become possible (Shirali-Shahreza and Shirali-Shahreza,
Information hiding is a technique of hiding secret using redundant cover data
such as images, audios, movies, documents, etc. This technique has recently
become important in a number of application areas. For example, digital video,
audio and images are increasingly embedded with imperceptible marks, which may
contain hidden signatures or watermarks that help to prevent unauthorized copy
(Jalab et al., 2009). It is a performance that
inserts secret messages into a cover file, so that the existence of the messages
is not apparent. Research in information hiding has tremendous increased during
the past decade with commercial interests driving the field (Jalab
et al., 2009).
The steganography has been used for long time before. The main use for it was
for military and government messages, nowadays; the approaches of steganography
become widely used for many purposes (Zaidan et al.,
2009). Anyway, the researchers provide and found out many approaches while
others enhanced the methods and the approaches of the steganography in order
to improve the steganographic applications, in this part of the thesis a discussion
about the existent methods or approaches for the steganography and how the researchers
improve it within more than 10 years will be presented.
One of the latest techniques that have been used in this area by researchers at the Mount Sinai School MOUNT SINAI Medical in New York in 1999, as they managed to hide the secret texts in chromosome strand human DNA by using a technique called genetic system coverage (Genomic Steganography) and by placing signs resolution to be agreed upon in the nuclei chromosomes and then integrate these with millions sentences and sent to the other end. To extract the secret message is soaking get special distinction sentences used on the other and then placed under the microscope to extract the required text.
The oldest authentications on steganography taken from the legendary stories
Greeks Herodotus and then back to the fifth century BC, these sources indicate
that they felt they fly head of the Messenger and then write the secret letter
in the head, leaving hair to grow then be sent to the required which is a re-extraction
letter. (Johnson and Jajodia, 1998; Zaidan
et al., 2008).
Authentications and other writing secret messages on the wood panels and then covered wax and will be hid those writing panels appear free of anything. And they were killing their animals as rabbit example corner confidential letter inside it.
Other means that the common use since the first century AD, invisible inks Invisible Inks, which was able to write a confidential letter with any other non-value-confidential and usually write between lines, for example those rabbis some fruit juices Fruit Juices, milk, urine, vinegar and all these species become dark and visible when exposed to heat the written document.
Then these kinds of inks evolved with the evolution of science chemical was
used vehicles carrying chemical characteristics of the same old species with
a more accurate and efficient have been used during the first and second world
wars in the military secrecy of correspondence. Other technical methods has
been used during world war II is sending a message hidden within another message
is not relevant and based on the idea of a nomination letters every word of
the letter counterfeit representation of characters from the characters letter
requested confidentiality (Johnson and Jajodia, 1998).
The earlier application of text based steganography founded during world war II; the Germans would hide data as microdots. This involved photographing the message to be hidden and reducing the size so that it could be used as a period within another document. FBI director J. Edgar Hoover described the use of microdots as the enemys masterpiece of espionage.
A message sent by a German spy during World War II read:
Apparently neutrals protest is thoroughly discounted and ignored. Isman hard hit. Blockade issue affects for pretext embargo on by-products, ejecting suets and vegetable oils.
By taking the second letter of every word the hidden message Pershing sails for NY June 1 can be retrieved.
More recent cases of steganography include using special inks to write hidden
messages on bank notes and also the entertainment industry using digital watermarking
and fingerprinting of audio and video for copyright protection (Naji
et al., 2009).
Moreover, there are numerous ideas for the same method is used to be more than characters, or take certain words or phrases within the text fake and leaving the rest. Finally, it should be noted that the senior researcher in the area of concealment and science-based organization itself is German Johannes Trithemius)) between 1462-1526 and the oldest books in the area of coverage Posted by Gaspari Schotti)) in 1665 in the name of (Steganographyica) and (400) contains a page where all the ideas included (Trithemius).
Nowadays, the steganography application for sharing secure message used the multimedia files as a cover carrier for the secure message, since that many approaches has been proposed to use different type of the covers to send the secure message.
The text-based steganography is so limited in capacity and it is the easiest approach to be altered even accidently since it use the visible text to hide the secure message. In addition, there is no measurement can be used for the text-based steganography to assure the confidentiality of the secure message.
The image based-steganography tried to improve the capacity where in the literature
more than 50% of the original image size has been used to hide the secure messages.
Since, there is a limitation on how much information can be hidden into an image
(Chang et al., 2002), making difficult to use
the image methods, then in order to help to increase collaborative documents
security. The video based steganography has been found to overcome the capacity
problem, the video consist of a number of images placed in a frames to be presented
in sequence one after the others. We can use any image within the video to hide
the secure message with it, the use of video based steganography has another
advantage as the discloser will facing a problem to attack the image since the
sequence of the image within the video is unknown for the attacker, so the attacker
need to check all the images within the video which make it more difficult to
attack the secure message. As well as the video-based steganography has the
lowest chances of being suspicious because of the quickly displaying of the
frames so its become harder to be suspected by the human vision system.
The capacity problems overcame by Noda et al. (2004)
the proposed method was based on wavelet compression for video data and Bit
Plane Complexity Segmentation (BPCS) steganography. The author enhanced the
capacity problems by using the video-based steganography.
A video error correction using steganography has been proposed in (Robie
and Mersereau, 2002) since the transmission of any data is always subject
to corruption due to errors, then the video transmission (because of its real
time nature) must deal with these errors without retransmission of the corrupted
data. However, the study proposed another application for the steganography
rather than for security purposes.
On another hand, Jalab et al. (2009) proposed
collaborate approach for select frame using Bit Plane Complexity Segmentation
(BPCS) for hiding data within MPEG Video. The proposed approach invented a high
secure data hidden using select frame from MPEG Video. However, the proposed
approach achieved a high capacity using video as a cover carrier but the steganography
alone unable to achieve high secure system for message sharing purposes.
Eltahir et al. (2009) proposed approach for
video steganography using the Least Significant Bits (LSBs). The method considered
the digital video file as separated frames and changed the output image displayed
on each video frame by hidden data that does not visually change the image.
With this technique, one can apply hidden information with more space better
than other steganography media. However, the authors used the video-based steganography
to enhance the capacity of the hidden message but the security requirements
such as data integrity has not appeared in the study (Eltahir
et al., 2009).
While Bhaumik et al. (2009) suggested another
video-based steganography. By using AVI videos which are large in size but still
can be transmitted from source to target over network after processing the source
video by using the data hiding and extraction procedure securely. There are
two different procedures, which are used in this study at the sender and receiver
sides respectively. The procedures are used as the key of data hiding and extraction
processes. However, the suggested key in this study does not meet the security
standards and it is unable to ensure the authentication and integrity of the
data or the message.
Wu et al. (2003) applied multilevel embedding
to allow the amount of embedded information that can be reliably extracted to
be adaptive with respect to the actual noise conditions. The authors proposed
strategies for handling different embedding capacity from region to region within
a frame as well as from frame to frame. The authors also embed control information
within the video to facilitate the accurate extraction of the user data payload
and to combat such distortions.
However, the enhancements of the security in steganography approaches can be
achieved by integrate the steganography with other techniques. In (Chae
and Manjunath, 1999) a video-based steganography proposed in which the embedded
signature data is extracted without knowing the original host video. The proposed
method enables high rate of data embedding. Embedding is based on texture masking
and utilizes a multi-dimensional lattice structure for encoding signature information.
Signature data is embedded in individual video frames using the block DCT. However,
the author claim that this approach is robust for motion compensated codes,
such as MPEG-2, without showing the proof for the robustness.
While in (Socek et al., 2007) the author proposed
video encryption algorithm designed for both lossless and lossy low-motion spatial-only
video codec. The proposed encryption method can thus be performed before compression
at the encoder side and after decompression at the decoder side. As well the
author introduced a new type of steganography as an extension to the encryption
approach. The proposed steganographic scheme enables disguising a video with
another video, which is a new concept in video-based steganography. However,
the encryptions usually increase the size of the cipher-text which is affecting
the capacity of the secret message.
On the other hand, Westfeld and Wolf (1998) presented
the steganography in a video conferencing, the video conference used for the
implementation of the steganographic system presented in this study works on
the H.261 standard. However, the H.261 is not adequate to be used on the Internet,
where just low bit-rate is available (De Oliveira, 1997).
Zaidan and Zaidan (2009) proposed a collaborate approach
between steganography and cryptography. The approach provided a high secure
data hidden using Public Key Infrastructure (PKI) method. However, the security
aspect has been considered in this study, although the size of the cipher-text
is a genuine problem for steganography. Furthermore, PKI encryption has been
proposed for the purpose of integrity. A solution of using hash function instead
of PKI can give faster processing, less size for authentication of the message.
The use of video as a carrier cover for the secure message is overcame the capacity problem and added small enhancement to the security aspects. The integration of steganography and cryptography techniques provided powerful systems for sharing secure messages.
HIDING DATA IN VIDEO FILE
Steganography in video files based on exploiting the YCbCr colour space: YCbCr or Y'CbCr is a family of colour spaces used as a part of the Color image pipeline in video and digital photography systems. YCbCr represents colours as a combination of three values:
||Y=The luminosity (roughly the brightness)
||Cb=The chrominance (roughly colour) of the blue primary
||Cr=The chrominance (roughly colour) of the red primary (Green
is achieved by using a combination of these three values)
This technique is based on YCbCr. YCbCr space that can remove the correlation
of R, G and B in a given image, as less correlation between colours means less
noticeable distortion. In this study they concentrate on human video images,
more specifically on human skin tones or colours for data hiding, note that
human skin colour can range from almost black to nearly colourless-appearing
reddish white due to the blood vessels under the skin-in different people. The
objective of this study is to combat the use of forged passport documents or
national identity cards, a security measure would be to embed individuals
information in their photos (Su et al., 2008).
Transform domain embedding: This is a more complex way of hiding information
in an image. Various algorithms and transformations are applied on the image
to hide information in it. DCT (Direct Cosine Transformation) is one such method,
which is used in JPEG compression algorithm to transform successive 8x8 pixel
blocks of the image, into 64 DCT coefficients each ( ).
DCT helps separate the image into parts (or spectral sub-bands) of differing
importance (with respect to the image's visual quality), embedding in DCT domain
is simply done by changing DCT coefficients, for example by changing the least
significant bit of each coefficient. One of the constraints of embedding in
DCT domain is that many of the 64 coefficients are equal to zero and changing
too many zeros to non-zero values will have an effect on the compression rate.
That is why the number of bits one could embed in DCT domain, is less that the
number of bits one could embed by the LSB method (Ahmed
et al., 2010).
Least significant bit insertion (Doerr and Dugelay,
2004): This is a very popular method because of its simplicity, in this
method; the LSB bit of 1 byte in the image is used to store the secret data.
The resulting changes are too small to be recognized by the human eye. Since,
this technique uses each pixel in an image, a lossless compression format like
bmp or gif has to be used for the image. If lossy compression technique is used,
some of the hidden information might be lost.
Considering video as separate images (Shirali-Shahriza,
2006; Kharrazi et al., 2004): In this method, each video frame
is considered as a separate image, in which information is hidden. The main
advantage of this method is the possibility of using the algorithms used in
image steganography and watermarking for video, but it requires a large amount
of computation. The algorithm we have suggested is almost similar to this method.
Real-time video steganography (Shirali-Shahriza, 2006):
This technique involves hiding the information on the output image of the instrument
(such as image displayed by an electronic advertising billboard). This method
considers each frame that is shown by the machine at any moment, irrespectively
of whether it is photo, text, or else, as an image. Then the system divides
the image into small blocks. If the pixel colours of the blocks are similar,
it changes the colour characteristics of a number of these pixels to a certain
extent so data information is hidden in the image.
In the following section the embedding of data into video based steganography. The embedding of data within video file start by selecting the desired video, after selecting the video, the system should read all the video frames and assign frame number to each frame and then the desired frames can be selected for further processing. Note, by selecting different frames sequence at every time provide more security and being harder to the attacker from attacks the frame due to unknown frame sequence.
The extraction of the data from the video file illustrated by read the video frames, then the desired frame can be identified by it sequence number, after identifying the frame number the extraction function can be started.
DISCUSSION AND ADVANTAGES
In this study, the review has shown above presents the steganography approaches
and how some researchers tried to enhance the limitation of steganography. Before
10 years the capacity of the secure image was limited (Moskowitz
et al., 2000) while now some researchers provide new approaches which
can embed secure message or image within more than 50% of the original image
size. As we shown in the previous work on steganography there are many use for
the steganography even not for pure security where sometimes it is usable for
error correction like in (Robie and Mersereau, 2002).
For the capacity purpose there is a limitation on how much information can be
hidden into an image, making difficult to use the image methods (Chang
et al., 2002). In the video steganography we have a flexibility of
make a selective frame steganography to higher the security of the system or
using the whole video for hiding a huge amount of data (Zaidan
and Zaidan, 2009). That reason makes the use of video-based steganography
more eligible. As well as, the confidentiality need to be tested through testing
the quality of steganographic object, as we will present in the second part
of this chapter the quality of steganographic object metrics are not sufficient
for these kind of test.
There are some techniques facing the capacity limitation problem, in general, the image has limited capacity when use it as a cover medium and its easier to being tested by the attacker it than the video where the video consist of a set of images and can use more than one image within the video as a carrier cover and more difficult to test it because the sequence of the stego image within the video is unknown by the attacker.
The video based steganography can be used as one video file, separated images in frames or images and audio files. Since that, the use of the video based steganography can be more eligible than other multimedia files.
In this study, we have clarified the knowledge of data hidden field. Furthermore, we have presented the history of the Steganography since ancient times until the present day. One of the challenges in this article reviewing the most important methods in the video file that used in this field. Steganography embedding types in video has been illustrated in this study. In addition, we have proposed the video architecture and how we can make use of the internal structure of the video to hide secure data. Finally, we demonstrate the advantage points of the hiding in video. Further direction can be done by using the audio part from the video file to hide a key for encryption and decryption purpose and the video frames as still image to hide the encrypted key.
This research has been funded by the University of Malaya, under the grant number (P0033/2010A). The author would like to take this opportunity to thank and acknowledge his supervisors: Dr. Hamid Jalab and Dr. Zarinah Mohd Kasirun, for having rendered their ceaseless and unconditional support throughout the entire duration of the study. The author would also like to extend his heartfelt gratitude to all his friends and associates who had offered him the much needed assistance and encouragement from the start to the end of the research period.