firewall configuration. The decentralised counterpart includes direct communication between push server and mobile device, requiring access over[, [e.g.]{},]{}the Internet to servers behind a company firewall, in turn necessitating special protection of the internal infrastructure. Taking a malicious service provider into consideration privacy concerns are added to the general ones regarding transport security. Potentially the NOC can access every message which is sent to a mobile device, allowing for information leakage. First and foremost the message content could be extracted and disclosed. Moreover, analysis of the collaboration between active users becomes possible. Both attacks have to be treated in the protocol design to enable end-to-end security and to conceal all sensitive information.

![Scenarios based on blob sealing (left) resp. key sealing (right)[]{data-label="graphs"}](graphs.eps){width="\textwidth"}

Protection of content is a major use case for trusted computing [@MPWGUC05]. We first present basic options to protect push content, and then describe the integration with th trusted ticket system of Section \[sec:TC-Tickets\]. Based on blob binding (see Section \[sec:TCess\]) the simplest scenario see the left diagram in Figure \[graphs\]. First, the data source signals the synchronisation server (SyncS) which then locates the target device, establishes communication, and controls the synchronisation relying on[, [e.g.]{},]{}OMA data synchronisation. Channel security 