—The success of a Public Key Infrastructure such as the Web of Trust (WoT) heavily depends on its ability to ensure that public keys are used by their legitimate owners, thereby avoiding malicious impersonations. To guarantee this property, the WoT requires users to physically gather, check each other’s credentials (e.g., ID cards), to sign the trusted keys, and to subsequently monitor their validity over time. This trust establishment and management procedure is rather cumbersome and, as we believe, the main reason for the limited adoption of the WoT. To overcome this problem, we propose a solution that leverages the intrinsic properties of Electronic Social Networks (ESN) to establish and manage trust in the WoT. In particular, we exploit dynamically changing profile and contact information, as well as interactions among users of ESNs to gain and maintain trust in the legitimacy of key ownerships without the disadvantages of the traditional WoT approach. We see our proposal as a...