WIPR — Public Key Identification on Two Grains of Sand
Abstract: We revisit a public key scheme presented by Shamir in 1994 (and
simultaneously by Naccache in 1992) and examine its applicability for general-purpose
RFID tags in the supply chain. Using a combination of new and established space-saving
methods, we present WIPR -- a full- edged public key identification scheme which
is secure yet highly efficient. 1024-bit WIPR fits completely (including RAM) into
5705 gate equivalents and has a mean current consumption of 10.88μA. The main novelty
in our implementation is the replacement of the long pseudorandom sequence, originally
stored on EEPROM in [16], by a reversible stream cipher using less than 300 bits
of RAM. We show how our scheme can be extended to offer tag-to-reader and reader-to-tag
authentication and how it can be fit into the existing RFID supply chain infrastructure.
