Abstract. Wireless Sensor Networks (WSN) are becoming a key technology in the support of pervasive and ubiquitous services. The previous notion of “PKC is too expensive for WSN” has changed partially due to the existence of new hardware and software prototypes based on Elliptic Curve Cryptography and other PKC primitives. Then, it is necessary to analyze whether it is both feasible and convenient to have a Public Key Infrastructure for sensor networks that would allow the creation of PKC-based services like Digital Signatures. Keywords - Wireless Sensor Networks, Public Key Cryptography, Public Key Infrastructure.