The approach works by giving all the devices on a network — or "nodes" — the ability to destroy themselves, taking any nearby malevolent device with them. "Bee stingers are a relatively strong defence mechanism for protecting a hive, but whenever the bee stings, it dies," says Tyler Moore, a security engineer at the University of Cambridge in the UK.

Self-sacrifice provides a check against malicious nodes attacking legitimate ones. "Our suicide mechanism is similar in that it enables simple devices to protect a network by removing malicious devices — but at the cost of its own participation," Moore adds.

The technique they have developed, called "suicide revocation," lets a single node decide quickly whether another node's behaviour is malevolent and shut it down. But there's a drastic cost: the single node must deactivate itself too. It simply broadcasts an encrypted message declaring itself and the malevolent node dead.

... "Nodes must remove themselves in addition to cheating ones to make punishment expensive," says Moore. "Otherwise, bad nodes could remove many good nodes by falsely accusing them of misbehaviour."