Original URL: http://www.theregister.co.uk/2010/01/15/smart_meter_crypto_flaw/

Texas Instruments to patch smart meter crypto blunder

Trivial key cracking

By Dan Goodin

Posted in Security, 15th January 2010 20:58 GMT

Texas Instruments plans to patch a cryptography flaw in a widely used chip that could allow attackers to remotely tamper with electronic power meters and other devices that connect to smart electricity grids.

The weakness resides in TI's Z-Stack software that runs on microcontrollers such as the CC2430. Encryption keys used to protect and authenticate communications between the devices are created using PRNGs, or pseudo-random number generators, that produces data that's trivial to predict, the company has confirmed.

That could allow attackers to remotely tap in to communications that travel over the grids' dedicated wireless mesh networks, researchers warn. The TI microcontrollers are also used in thermostats, display panels, and other home appliances designed to work on smart grids.

"If you can figure out those keys, you essentially don't have encryption anymore," said Mike Davis, a senior security consultant for IOActive who has audited the security of smart meters. "That may mean you get to a place where it's possible to send malicious packets on the network or any number of attacks."

Joseph Reddy, a systems engineer in TI's low-power RF software group, said his team was in the process of rolling out Z-Stack version 2.3, which would replace the firmware's PRNG with a cryptographically secure RNG.

"For these types of applications, it's critical to have very secure communication because you don't want to have just anyone to be able to control all your home appliances," he told The Register.

The weakness, which was documented last week by security researcher Travis Goodspeed, ought to serve as a cautionary tale for the untold number of companies working on parts that will make up the emerging smart grid. Unlike electricity grids in use today, they will be able to save money and conserve resources by allowing two-way communication between electricity users and the power plants that serve them.

Smart grids will also allow smart meters in consumers' garages or utility rooms to communicate directly with dish washers and other appliances, so users will know exactly how much power is being consumed at any given time. Depending on other considerations, such as the current supply of power, appliances can be programmed to shut down until the availability of electricity is more plentiful or off-peak rates are available.

That's a heady vision, but it comes at considerable risk if the components that make up the smart grid aren't designed securely. TI's crypto blunder makes one wonder how many other critical pieces of this complex puzzle are also left wanting.

Cryptographer Nate Lawson has more here. ®