Reconfiguring Crypto Hardware Accelerators on Wireless Sensor Nodes

Running strong cryptographic algorithms on wireless sensor nodes is extremely difficult due to their limited resources. Hardware accelerators are a suitable means to speed up the computation and reduce power consumption. The drawback of crypto ASICs is the loss of flexibility. In this paper we will shortly introduce a modular design of elliptic curve accelerators which allows to be adjusted to several NIST recommended curves by replacing its reduction unit. This partial reconfiguration will be executed on a Spartan 3 FPGA. The visualization will be done in the following way. Standard motes will be connected to the FPG. On the motes the algorithms will be executed in software. Switching between ECC with a long key, i.e. 571 bit and those with short key length, e.g. to a key length of 163 bit, has a remarkable effect on the execution time. En-/decrypting messages sent to and received from the motes at the FPGA will show that ECC implementation has been reconfigured according to the selected curve on the motes.