EncryptionLiving bacteria for perfect encryption system

Published 28 September 2011

Researchers have developed fluorescent bacteria that encode secret messages, creating, in effect, a living invisible ink; this method could be harnessed for secret communications as well as for anti-counterfeiting; messages may be encoded by genetically engineering bacteria to produce fluorescent colored proteins, then printing them in a grid

Bactrium trained for data storage // Source: ning.com

Researchers have developed fluorescent bacteria that encode secret messages, creating, in effect, a living invisible ink. Simple messages may be encoded by genetically engineering bacteria to produce fluorescent colored proteins, then printing them in a grid. This method could be harnessed for secret communications as well as for anti-counterfeiting.

The BBC reports that the process, called Steganography by Printed Arrays of Microbes (SPAM), is simple. The team first developed seven different strains of the E. coli bacteria that grow in different colors (when bathed in ultraviolet light).

They then devised a simple coding scheme based on pairings of the colors to represent letters of the alphabet (and a few symbols). They then applied the bacteria to a plate of agar (a gelatinous substance that serves as food for the bacteria) where they grew into their respective color types. Next, a sheet of a nitrocellulose type material, which looks like paper, was pressed over the plate of agar, imprinting it (the nitrocellulose sheet) with the bacteria. The result was then dried, causing the coloring attribute to disappear. The sheet can then be folded, placed in an envelope, and sent to its destination.

The recipient would press the sheet onto an agar plate and the bacteria would grow once again into their coloring, revealing the coded message.

Professor David Walt of Tufts University told the BBC that this coding system is “practical, as it uses seven easily discernable colors in the visible spectrum,” but that other coding systems may be developed that make use of other colors and other combinations representing each letter.

The developed message may then be decoded in a variety of different ways.

There are other ways to encode – and decipher – the message carried by the bacteria:

·         Some of the genetically engineered bacteria will fluoresce differently depending on the wavelength of light shone onto them, so using different lights will result in different messages. The sender would send a “photo-cipher” that would tell the recipient which wavelength of light will retrieve the message; any other wavelength would result in a meaningless string of letters.

·         In addition to fluorescence, some of the bacteria can be engineered to be resistant to certain antibiotics. This means that when the recipient develops the bacterial array on the growth medium, different messages can result from impregnating that medium with different antibiotics.

Walt noted that “There are multiple levels of security built into it. You have a code and a key that is virtually impossible to break as it is made up of an endless number of combinations of growth media, chemicals and development times.”

There is also this benefit: with a living bacterial system, the information can be released on-demand. “The undeveloped SPAM really are invisible, you can’t even see where they are” said Walt.

— read more in Manuel A. Palacios et al., “InfoBiology by printed arrays of microorganism colonies for timed and on-demand release of messages,” Proceedings of the National Academy of Sciences (26 September 2011) (10.1073/pnas.1109554108)