Holographic Sonar Cryptography

Atomic Snarl writes: "New Scientist.com has this story on how to encrypt a underwater sonar message using multiple sound path timing. By detecting and adapting for the current variations on underwater sound channels, the transmitted message can be received intelligibly only at a single point. This holographic approach suggests a method of web encryption using multiple hop paths and ping times to create a message which can only be decoded when received at a specific target node!"

Comments

Speed of sound versus ping times

[Chiasmus_]

It seems to me that the speed of sonar through water is a physical certainty; that's why we can accurately use it to detect the distance from an object.

Internet traffic is another matter. If I tried to use a ping time to measure the geographic distance to another server, I'd be about as scientific as the Slashdot poll.

Am I wrong, or could internet latency give or take 100 ms or so from a ping, rendering the encrypted message readable by.. no one?