Hiding in the Light
Raytheon employs quantum physics to make communications secure
When Saikat Guha visits an ATM or buys a product on the Internet, he knows what types of security systems are running behind the scenes to keep his data safe. He also knows just how those systems could be breached.
"Most current security protocols rely on an adversary not having the computing power to factor huge numbers," says Guha, a senior scientist at Raytheon's BBN Technologies . As computers gain power, however, these common security approaches could leave data vulnerable.
That's what Guha is working to prevent — not just for consumers on the Internet but for military forces and governments sending and receiving highly sensitive security data. Guha and his Raytheon colleagues worldwide are making breakthroughs in secure communications using the principles of quantum physics.
Steps to safety
"In quantum security," says Guha, "you want the data to be undecodable no matter how much computational power an adversary may have."
This super-secure communications method applies quantum physics to three main objectives. First, the intended receiver must be able to reliably decode the data you send. Second, unintended receivers must not be able to decode the data, no matter how powerful their computing ability. And finally, for the highest level of security, an eavesdropping adversary should not even know you're communicating.
A technology known as quantum key distribution is central to achieving these requirements. With QKD, two distant parties connected by an optical channel can generate a shared random key based on quantum physics rather than on complex computations. The key generation process in QKD uses two-way communication over a standard communication channel that does not need to be secured. The quantum-secured shared keys can be used later to encrypt and decrypt communications.
Ultimately, security for the most sensitive data may involve a sort of invisibility cloak. "There's a certain amount of noise in communication channels that you can't avoid," Guha explains. "So you hide your communication in that noise."
Here's how it works. Two parties use QKD to share a secret codebook. Then the sender embeds very small amounts of data into the noise of the communication channel. The receiver can then decode the data, but an adversary can't detect it. Using jammers to generate random noise can do even more to thwart eavesdroppers.
With this QKD approach, "You don't have to rely on any hard mathematical problem," says Guha. "You're secure against the most powerful adversary."