A molecular encryption key was embedded in ink (left image) of a letter (right image), which was mailed and analyzed to decrypt a file. Credit: Adapted from ACS Central Science 2022, DOI: 10.1021/acscentsci.2c00460.
Key Points:
- LC-MS is a go-to technique to deconstruct polymer sequences.
- This method allows the opportunity to hide secret messages in letters and plastic objects.
When L. Frank Baum wrote “The Wonderful Wizard of Oz” in 1900, he probably did not envision the text being used as a molecular encryption key between laboratories at the University of Texas at Austin—but that’s exactly what the Anslyn Research Group did.
As data sharing became more common and security became more important, researchers began exploiting molecular strategies, including DNA chains and polymers, to durably store and transport encryption keys. Currently, nucleic acids store more information than polymers, as additional information makes polymers too long and too difficult to extract information from.
Recently, however, distinguished chemist and professor Eric Anslyn developed a method to deconstruct polymers in a sequential way, allowing their structures to be determined more easily with liquid chromatography mass spectrometry (LC-MS). With that, Ansyln and his colleagues wanted to test the method on a mixture of unique polymers hidden in ink to see if the approach could be used to reveal a complex molecular encryption key.
According to the study published in ACS Central Science, the researchers generated a 256-character-long binary key that could encrypt and decrypt text files when entered into an algorithm. Next, they encoded the key into polymer sequences of eight 10-monomer-long oligourethanes. Only the middle eight monomers held the key, with the two ends acting as placeholders for synthesis and decoding. The decoding placeholder was a unique, isotopically labeled “fingerprint” monomer in each sequence, indicating where each polymer’s encoded information fit in the order of the final digital key.
Then, the researchers mixed the eight polymers together and used a sequential depolymerization method and LC-MS to determine the original structures and the digital key. Finally, one group of the researchers combined the polymers with isopropanol, glycerol and soot to make an ink, which they used to write a letter that they mailed to other colleagues, who didn’t know the encoded information. These scientists extracted the ink from the paper and followed the same sequential analysis to successfully reconstruct the binary key.
They entered the encryption key into the algorithm, revealing a plain text file of “The Wonderful Wizard of Oz.”
The researchers say that their results demonstrate that molecular information encryption with sequence-defined polymer mixtures is durable enough for real-world applications.
Data provided by American Chemical Society.