Forget ‘password123’, you can now encrypt things with colored light

Researchers at the Technical University of Lausanne (EPFL), have found a new way to encrypt messages. They used silver nanostructures and shone polarized light on them. The colors then created are ideal for encrypting messages, EPFL reports in a press release.

Quaternary code

The colors are created only when light shines on the silver nanostructures at a specific angle. These colors are then numbered according to a quaternary code, numbering 0,1,2 and 3. For example, if the system creates a sequence of orange, yellow, red and white, this would produce a particular number sequence, in this case 1,0,2,0.

The researchers translated these numbers into letters. The code 1,0,2,0 is the letter H. Interestingly, the same number can have a different color by using the quaternary system. Olivier Martin, researcher on the project, explains that this makes the system more secure. “This makes it harder for a computer to guess a good sequence, because in this case the colors yellow and white are both 0.”

This method can be used because the nanostructures of the silver respond uniquely to polarized light. The direction from which the light comes is crucial. Only the correct combination of vertical, horizontal and diagonal polarization directions reveals the secret message. Any other direction gives a message of random letters.

Future with quantum computers also calls for encryption of older data

Since it will not be very long before quantum computers are commonplace, people are already working hard on the security for this new situation.

Banknotes and art

Another application of this technology is use in conjunction with the human eye. For example, nanostructures can be used in banknotes and other securities that make such bills even more difficult to copy for counterfeiters.

In addition, a large amount of information can be hidden in a small area, making miniature works of art possible. Martin also sees the artistic side of his discovery. “Nano-materials and color are at the intersection of high technology and art. “