By Mansoor Khan, University of Connecticut, iBridge Network Innovations – May 05, 2010 at 11:14PM
This technology relates to providing secure communications in ad-hoc wireless communication systems.
The broadcast nature of a wireless link provides a natural eavesdropping and intervention capability to an adversary. Thus, securing a wireless link is essential to the security of a wireless network, and key generation algorithms are necessary for securing wireless links.
However, traditional key agreement algorithms can be very costly in many settings, e.g. in wireless ad-hoc networks, since they consume scarce resources such as bandwidth and battery power.
This invention presents a novel approach that couples the physical layer characteristics of wireless networks with key generation algorithms. It is based on the wireless communication phenomenon known as the principle of reciprocity which states that in the absence of interference both transmitter and receiver
experience the same signal envelope.
The key-observation here is that the signal envelope information can provide to the two transceivers two correlated random sources that provide sufficient amounts of entropy which can be used to extract a cryptographic key.
In contrast, it is virtually impossible for a third party, which is not located at one of the transceiver’s position, to obtain or predict the exact envelope; thus retrieve the key.
Since in the presence of interference strict reciprocity property
can not be maintained; our methodology is based on detecting deep fades to extract correlated bitstrings.
In particular, we show how a pair of transceivers can reconcile such bitstrings and finally flatten their distribution to reach key agreement.