A team of Chinese researchers say they have developed a method to camouflage secret military communications in the sounds emitted by sperm whales in an effort to help the country’s submarines avoid detection, reports Hong Kong newspaper of record South China Morning Post (SCMP).
In a nutshell, the researchers can edit and embed audio signals into recorded whale sounds, then build a coding system around these signals to make them more secure. While the technology is new, the concept of hiding secret messages within a bigger picture is not. Steganography has been used since ancient times, such as when Da Vinci painted a hidden code in the Mona Lisa or when British and American armies sent communications using invisible ink during the revolutionary war. In a more modern twist, hackers have taken to the ancient warfare tactic by hiding malicious codes in benign software.
In today's oceans, submarine reconnaissance systems are constantly scanning and sweeping underwater areas for submarine signals, but in the process they are filtering out the sounds of sperm whales and other marine mammals. Since sperm whales are found in oceans around the world, using their signals is a perfect Trojan Horse. Toothed whales (Odontocetes) like sperm whales use echolocation to hunt and navigate in light-deprived areas in a similar way to how blind bats can “see” the world around them; the sound is emitted from the whale’s melon (forehead) and reflects off of objects. Submarines use sound navigation and ranging (SONAR) in the same way, emitting pulses of sound waves that reflect off an object and come back to the ship to indicate where a target might be.
Lead researcher Jiang Jiajia told SCMP that submarines can keep their sound pulses and other communications off enemy radars in one of two ways. They can either alter certain audio characteristics that essentially turn them into a difficult-to-crack code or send weaker signals that are harder to pick up – both strategies have their downfalls. First, encrypting audio signals could tip off listening enemies who are looking for unnatural sounds. On the other hand, weakened signals get weaker as they travel longer distances, creating the potential of missing their target.
Steganography, Jiajia says, is advantageous over encryption and other camouflage methods simply because it does not attract attention. Technology that encrypts the messages can further make underwater communication more secure, so that even if these secret signals are detected, they are more difficult to crack.
However, echolocation is an extremely sensitive process and it’s not clear how (or if) these altered sounds would impact whale populations.
[H/T: South China Morning Post]