Mobile devices may share resources even in the presence of untrustworthy devices. To do so, each device may use a computational model that on input of reputation information produces trust assessments. Based on such assessments, the device then decides with whom to share: it will likely end up sharing only with the most trustworthy devices, thus isolating the untrustworthy ones. All of this is, however, theoretical in the absence of a general and distributed authentication mechanism. Currently, distributed trust frameworks do not offer an authentication mechanism that supports user privacy, whilst being resistant to “Sybil attacks”. To fill the gap, we first analyze the general attack space that relates to anonymous authentication as it applies to distributed trust models. We then put forward a scheme that is based on blinded threshold signature: collections of devices certify pseudonyms without seeing them and without relying on a central authority. We finally discuss how the scheme tackles the authentication attacks.