Storing data in ink sounds like science fiction. A handwritten letter, a priori completely innocuous, hides secret information impossible to see at thenaked. Yet this is what researchers from . They published their method in the journal .
The method described does not allow, at least for the moment, to transmit a complete database in this way, but only a very small quantity of information. To prove that their technique works, the researchers encrypted the text of the book The Wizard of Oz by Lyman Frank Baum, which they passed on in the classic way. It’s here256-bit AES that they transmitted in ink from a handwritten letter.
A technique mixing cryptography and steganography
is a polymer composed of four different, the researchers created a called defined sequence, composed of a long chain of monomers. The key was converted to hexadecimal (base 16) to be encoded using 16 different monomers. The researchers thus created composed of 10 monomers. The first and last monomer of each group is an isotopic tracer which makes it possible to determine in which order to read the various polymers.
The researchers thus succeeded in encoding 32 bits of information in each polymer. The 256-bit key therefore required a total of eight polymers composed of groups of 10 monomers. They then mixed them withisopropyl, and some to create ink, used to write a simple letter. They thus used the in other words a technique for . The real message is therefore not the content of the letter, but the ink used.
Polymers could one day be used to store large amounts of data
In order to validate the technique, a first group of researchers participated in the development of the letter. It was written on plain paper and then mailed to one of the other co-authors of the article. He used methylene chloride to extract the polymers in the ink, and received information on the method of encoding data at the level of. His team managed to sequence the molecules and recreate the key to correctly on the first try, so she was able to decipher the text of the Wizard of Oz that he received.
This technique is currently quite long and complicated to implement. The researchers want to explore the use of robots to be able to automate the writing and reading of molecules. While a 256-bit sequence represents relatively little information, the goal of researchers is not just to transmit encryption keys. The density of the data recorded in the molecules of the polymers, which, is much higher than a hard disk. In the longer term, researchers hope to be able to store large amounts of information in this way.