When exploring solutions to some of the formidable security problems facing RFID deployment, researchers are often willing to countenance the use of a strong symmetric primitive such as the AES. At the same time it is often claimed that public key cryptography cannot be deployed on low-cost tags. In this paper we give a detailed analysis of the GPS identification scheme. We show that with regards to all three attributes of space, power, and computation time, the on-tag demands of GPS identification compare favourably to the landmark AES implementation by Feldhofer et al.. Thus, assumed limits to implementing asymmetric cryptography on low-end devices may need to be re-evaluated.