Principal Investigator Anantha Chandrakasan
Cryptographically Secure Ultra-Fast Bit-Level Frequency Hopping for Next-Generation Wireless Communications Current Internet-of-Things devices communicate via Bluetooth Low Energy (BLE). Unfortunately, BLE-connected devices are vulnerable to a wide range of attacks; this work specifically addresses selective jamming denial of service where the adversary corrupts transmitted messages targeting a single victim. Selective jamming is particularly challenging as it conceals the attacker’s identity contrary to broadband-wireless jamming. To illustrate this type of attack, we demonstrate selective jamming against a commercial fitness BLE-device. This form of attack can cause serious harm such as in the case of insulin pump medical devices.
The primary vulnerability of BLE is founded in the communication protocol which uses frequency hopping to send a message, which is decomposed into data packets, over rapidly changing sub-frequencies. The carrier frequency hops among these sub-frequencies at a relatively slow rate of 612µs per data packet. Conversely, an attacker needs only 1µs to identify the carrier frequency, then block the remainder of the data packet sent on that sub-frequency. To counter this attack, we developed physical-layer security through an ultra-fast bit-level frequency hopping scheme which sends every data bit on a unique carrier frequency while achieving a 1μs hop period.
In addition, a challenging issue is that traditional modulation schemes, such as the BLE Gaussian frequency shift keying (GFSK) modulation with fixed carrier offset of ± 250kHz for Bit 1 and Bit 0, permit the attacker to selectively overwrite individual bits in a packet once the carrier frequency is localized. The attacker gains control over the packet that will be received by the victim. We protect against this attack by implementing a cryptographically secure data-driven dynamic channel selection scheme that enables 80- way pseudorandom FSK modulation and provides data encryption in the physical layer.
In this work, we demonstrated the first integrated bit-level frequency-hopping transmitter that hops at 1µs period and uses data-driven random dynamic channel selection to enable secure wireless communications with data encryption in the physical layer.