Researchers have developed a method that utilises blockchain technology to improve the capacity for secure communication for robot teams.
This novel blockchain technology – with transaction-based communication systems – could be applied to guarantee that teams of robots accomplish their objectives even in a scenario where some of the robots are hacked.
Imagining a future of firefighting robots
It is possible that in the future, autonomous drones, equipped with advanced sensing equipment, could have the capacity to search for wildfires. Once they have located the source of the wildfire, the leader robots could relay the location to a group of firefighting drones that rush over to the source of the fire.
However, theoretically, one or more of these leader robots could be hacked by a malevolent agent and send incorrect directions. In this scenario, the follower robots would be led further away from the source of the fire without the knowledge they had been misled.
Blockchain technology provides security
The utilisation of blockchain technology as a communication tool for a team of robots may offer security and safeguard against deception, according to a study by researchers at MIT and Polytechnic University of Madrid.
The team’s research findings have been published in IEEE Transactions on Robotics.
The research could also have applications in cities where multirobot systems of self-driving cars are delivering goods and transporting people across town.
A blockchain provides a tamper-proof record of all transactions — in this case, the messages issued by robot team leaders — so follower robots can ultimately detect discrepancies in the information trail.
Leader robots apply tokens to signal movements and add transactions to the chain, and then forfeit their tokens when they are ‘caught’ in a lie. Therefore, this transaction-based communications system confines the number of lies a hacked robot is capable of spreading, according to Eduardo Castelló, a Marie Curie Fellow in the MIT Media Lab and lead author of the paper.
“The world of blockchain beyond the discourse about cryptocurrency has many things under the hood that can create new ways of understanding security protocols,” Castelló explained.
Blocks containing directions
In this simulation-based study, the information stored in each block is a set of directions from a leader robot to followers. If a malevolent robot tries to modify the content of a block, it will change the block hash; thus, the changed block will no longer be connected to the chain.
As well as this, the blockchain offers a permanent record of all transactions. As all followers can ultimately see all the directions issued by leader robots, they can see if they have been misled.
For example, if five leaders send messages telling followers to move north, and one leader sends a message telling followers to move west, the followers could disregard the contradictory direction. Even if a follower robot did move west by mistake, the misled robot would eventually recognise the error when it contrasts its moves to the transactions stored in the blockchain.
In the approach the researchers constructed, every leader obtains a fixed number of tokens that are applied to add transactions to the chain — one token is necessary to add a transaction. If followers verify the information in a block is incorrect, by examining what the majority of leader robots signalled at that particular step, the leader loses the token. Once a robot is out of tokens, it can no longer send messages.
“We envisioned a system in which lying costs money. When the malicious robots run out of tokens, they can no longer spread lies. So, you can limit or constrain the lies that the system can expose the robots to,” Castelló explained.
“Since we know how lies can impact the system, and the maximum harm that a malicious robot can cause in the system, we can calculate the maximum bound of how misled the swarm could be. So, we could say, if you have robots with a certain amount of battery life, it doesn’t really matter who hacks the system; the robots will have enough battery to reach their goal.
“You can design your system with these tradeoffs in mind and make more informed decisions about what you want to do with the system you are going to deploy,” he added.
Going forward, Castelló plans to develop off this work to construct novel security systems for robots utilising transaction-based interactions.
“When you turn these robot systems into public robot infrastructure, you expose them to malicious actors and failures. These techniques are useful to be able to validate, audit, and understand that the system is not going to go rogue. Even if certain members of the system are hacked, it is not going to make the infrastructure collapse,” he concluded.