Paper Summaries (Part 1)
Below are summaries of some of the papers mentioned in my Description Stage and Papers blog post.
Singh, S. & Agarwal, G. (2010). Hiding image to video: A new approach of LSB replacement.
This paper describes a technique for hiding an image in a video by hiding each row of pixels in the first row of pixels of different video frames. Although, this paper is dedicated to explaining the algorithm the authors propose, a very brief explanation of LSB encoding. The abstract also claims (without reference or evidence) that hiding data across multiple frames is “very difficult to analyse”.
Prabhakaran, N. & Shanthi, D. (2012). A New Cryptic Steganographic Approach using Video Steganography.
Here the authors describe a method of encoding a message (encrypted with AES), in a video, “embedding in both the horizontal and vertical components of the motion vector”.
In the introduction of this paper the authors acknowledge the necessity for steganography and cryptography for secure communication, and outline what cryptography and steganography involve and how they differ.
This paper claims that Image steganography is the most commonly used type of Steganography, unfortunately they do not provide any references or stats to justify this statement.
Frequency domain and spatial domain techniques for images steganography are also discussed and defined. Prabhakaran and Shanthi define these terms as follows:
- Spatial domain techniques embed the message directly in the intensity of the pixels.
- Frequency domain (a.k.a-- “transform domain”) techniques first transform the image before embedding the message.
Some pre-existing techniques for video steganography are discussed and referenced. From this discussion of pre-existing techniques, I have identified that encoding in H.264 is slightly different, as different block sizes are used during the inter prediction stage. This is something that Spyridon K et al. have used in their work on steganography with the H.264 format 1.
The authors describe an interesting technique for their stego-module that deals with lossy compression issues with JPEG image formats.
Al-Frajat, A. K., Jalab, H. A., Kasirun, Z, M., Zaiden, A. A. & Zaiden, B. B. (2010). Hiding Data in Video File: An Overview.
This paper gives an overview of existing steganographic techniques used to hide information in video containers. In addition, this paper provides a reference to work by Zaidan et al. (2009), which identifies that steganography was initially used by military and government organisations. However, steganography is now widely used for many different purposes.
A detailed history of steganography is explained with examples of genuine linguistic steganography. Steganographic capacity is discussed; video is identified as having the largest capacity of all digital media (images, audio and video).
This paper discusses in detail the work of others in the field of video steganography and explains important aspects of video and image manipulation – such as the YCbCr colour model.
References in this paper are extensive.
Mozo, A. J., Obien, M. E., Rigor, C. J., Rayel, D. F., Chua, K. & Tangonan, G. (2009). Video Steganography using Flash Video (FLV).
According to this paper, FLV has a small file size and a simple structure. This paper discusses several references that detail techniques for encoding messages in video with 100% lossless extraction. As such, the authors have achieved a technique of embedding data in an FLV file with 100% lossless extraction.
This paper mentions one of the pre-existing techniques using fourier transforms with the MPEG4 file format. As further reading, it would be worth investigating fourier transforms.
FLV is a file format intended to stream. It allows for frequent multiplexing of audio and video data. Multiplexing audio and video regularly is important for video files that are streamed. This allows audio and video to be played back without waiting for different file parts to buffer as audio and video multiplexing puts associated audio and video data close together.
The authors discuss how FLV files allow for additive steganography – the video stream is more tolerant of this than the audio stream.
Given the research carried out to write this paper, it would appear that the FLV file format is highly robust and can even have audio and video tags removed without corrupting the file.
Zhang, C., Su, Y., Zhang, C. (2008). Video steganalysis based on aliasing detection.
The principle described in this paper is quite mathematically involved and details steganalysis only. The technique proposed in this paper uses aliasing to detect modifications caused by steganography application. Hidden data is usually high frequency in comparison to the unmodified cover image. The technique proposed by Zhang and Zhang relies on isolating the high-frequency signals in the cover object to identify the hidden contents.
Footnotes:
- Kapotas, S.K., Patras Varsaki, E.E., Skodras, A.N. (2007). Data Hiding in H. 264 Encoded Video Sequences.