New steganography technique relies on letter shapes
Indian researchers say cunning scheme is secure, has good signal:noise ratio
A trio of Indian researchers have proposed a method of steganography which hides messages in by using non-random distribution of letters with or without straight lines.
Steganography is a group of techniques for hiding messages in plain sight. Microdots, tiny text written inside a full stop and only legible when magnified, are one steganography technique. Steganography is hard to detect and decrypt, so much so that this paper from the US National Science and Technology Council (PDF) wrings its hands about it's potential use by terrorists.
The new method for steganography has been outlined by Shraddha Dulera and Devesh Jinwala, both from the Department of Computer Engineering at the S V National Institute of Technology in Surat, India, and Aroop Dasgupta of Gandhinagar ‘s Bhaskaracharya Institute for Space Applications and Geo-Informatics. The trio’s paper, Experimenting with the Novel Approaches in Text Steganography, suggests that the low signal-to-noise ratio required by many current steganography techniques makes for slow decipherment.
The trio’s alternative is a system based on the characteristics of letters in the Hindu-Arabic alphabet, which they group into those possessing straight lines and those possessing curved lines. Each group is assigned a value of either zero or one as the basis for a binary code.
One method for using this scheme is to “ … generate a random string that contains the single letters (from alphabet) as the cover text. Subsequently, whenever we want to hide a ‘0’ bit in the input text file, we use the letters from the group A amongst the letters generated; whereas whenever we wish to hide a ‘1’ bit, we use the letters from the group B amongst the letters generated.”
A second scheme sees curved or straight letters capitalised at the start of sentences, so that the sentence “All birds can fly. Ostrich is a bird. Ostrich can also fly” yields a binary value of 100.
The trio’s third scheme proposes to further divide the alphabet into letters with:
- A straight horizontal middle line;
- One vertical straight line;
- A diagonal line.
By doing so, it becomes possible to create a code in which capital letters can have a binary value of 0, 1, 10 or 11.
The trio assert that “Our analysis reveals that our approaches impart increased randomness and because of randomness, these approaches are noticeable but it cannot be decoded until a user is not aware about these approaches. In addition, the proposed approaches are also immune to retyping and reformatting of text.”
But they also warn that “… one of the weaknesses of the proposed approaches is that once their applicability is known, they can easily be attacked. Hence, it is essential to keep the application of a particular approach to a particular data set secret, while using them.”
Do you promise not to tell? ®
Re: Yeah, who could possibly tell that a random-appearing string of characters .....?
And besides, a random appearing string of characters might be a program in Perl
Re: Why bother with steganography?
Amanfrommars, is that you?
Not real steganography
"Real" steganography is hiding a message in an already constructed text or picture in a way that does not obviously change that text or picture. What is described is a form of cryptography.
Text steganography could, for example, be by varying the amount of space between words to encode a hidden message: On the surface, the text is unaltered and looks perfectly natural, but there is a message hidden. If you actually have to construct a message specifically to encode the message, it is not really steganography -- it is just low-density cryptography similar to texts where the initial letters of the words encode a message or texts where the length of the words encode digits (like "How I wish I could recollect pi. "Eureka!" cried the great inventor: Christmas pudding, Christmas pie, is the problem's very centre"). The challenge of these is to make the text seem natural, while it has to obey non-trivial constraints. Real steganography should have no such constraints, but be able to encode any text (or picture) to hide a message.