Researchers from the Shanghai Jiao Tong University in China are suggesting that infrared radiation (IR) from the human body can be harnessed for security applications.

Using IR — essentially the heat given off the body — emitted from the human hand, the team proposes using the invisible light to decrypt secret data and create passwords for sensitive data.

"The use of human components as IR light sources may provide a promising way to increase the controllability and flexibility of the engineered systems," explained the authors. "[T]he human hand is not just a natural and powerless IR light source, but also a multiplexed light source with each finger serving as an independent light source."

A depiction of the infrared light signals emitted by the human hand. Source: An et al./PNAS

To demonstrate how this would work, the researchers applied a low-reflectivity polydimethylsiloxane spray to aluminum, encrypting an invisible message "tared" at ambient temperature. In other words, upon exposure to additional infrared radiation from the hand, the invisible message was made visible.

Additionally, the team determined that the decryption process could potentially be modified for different depths, which means that fingerprints could serve as an encryption key that cannot be copied.

The research appears in the Journal of the National Academy of Sciences