A Faraday cage or Faraday shield can best be defined as an enclosure formed by conductive material that is used to block electric fields. As such, Faraday cages either heavily attenuate or block the reception and transmission of radio waves, which are a form of electromagnetic radiation.
Image Credit: Frank Vincentz (Via Wikipedia)
Unfortunately, there is no Faraday cage large enough to shield the burgeoning Internet of Things and related infrastructure from certain hacks such as simple power analysis (SPA) and differential power analysis (DPA). To be sure, all physical electronic systems routinely leak information about their internal process of computing. In practical terms, this means attackers can exploit various side-channel techniques to gather data and extract secret cryptographic keys from IoT endpoints.
“Regardless of specific instruction set architecture (ISA), most industry security solutions on the market today can be soundly defeated by side-channel attacks,” said Simon Blake-Wilson, a VP at Rambus’ Cryptography Research Division. “In fact, even a simple radio is capable of gathering side-channel information by eavesdropping on frequencies emitted by electronic devices. In some cases, secret keys can be recovered from a single transaction clandestinely performed by a device several feet away.”
The burgeoning IoT already comprises millions, if not billions, of connected endpoints powered by chips that are vulnerable to side-channel attacks. Such unprotected silicon (e.g., CPUs, MCUs, MPUs) can be found in a wide range of electronic devices including wearables, medical equipment, vehicles, smart appliances and rapidly evolving smart city infrastructure.
Perhaps not surprisingly, vulnerable Field Programmable Gate Arrays (FPGAs) are also gaining traction among IoT device manufacturers. Pankaj Rohatgi, a Security Technology Fellow at Rambus’ Cryptography Research Division, says the advantages of FPGAs include reduced time-to-market, field-configurability and lower up-front costs.
“FPGAs are increasingly being relied upon to protect highly-sensitive intellectual property, trade-secrets, algorithms and cryptographic keys. They are also a natural fit for certain elements of the IoT,” he explained. “Sensitive FPGA applications – such as power grids, medical devices and semi-autonomous vehicle infrastructure – all require strong tamper resistance to protect both the secrets contained within these devices as well as the data they process.”
As Rohatgi confirms, power analysis attacks are among the most important to protect against, since they are non-invasive, widely understood by adversaries and easy to execute via inexpensive off-the-shelf equipment.
“Fortunately, specific DPA countermeasure strategies can be employed to protect FPGA-based IoT devices and related infrastructure,” he said. “These include techniques to minimize information leakage, generating noise to drown out leakage signals, the use of randomness to mask computational intermediates, algorithm and implementation obfuscation as well as the use of protocols designed to preserve secrecy even in the presence of (some) leakage.”
However, as Blake-Wilson emphasizes, side-channel attacks are only one specific attack vector threatening the IoT.
“The current security paradigm associated with the mobile and PC world is undeniably flawed. I find it difficult to believe that any serious industry player is honestly satisfied with the status quo, in which serious or even critical vulnerabilities disclosed on an almost daily basis are patched with hurriedly coded software and firmware updates,” he concluded. “A ‘good enough’ approach may have been tolerated for smartphones and tablets, but the industry cannot afford to relegate security to a tertiary concern for an IoT that may very well ultimately affect every aspect of our daily lives. A new paradigm, designed from the ground up to provide secure foundations for connected devices, is clearly long overdue. Devices need to be secured throughout their lifecycle from chip manufacture, to day-to-day deployment, to decommissioning. Alongside side channel attacks, secure provisioning and configuration are crucial issues that we are addressing with CryptoManager.”