Privacy-aware presence management in instant messaging systems

Information about online presence allows participants of instant messaging (IM) systems to determine whether their prospective communication partners are able to answer their requests in a timely manner, or not. This makes IM more personal and closer than other forms of communication such as e-mail. On the other hand, revelation of presence constitutes a potential of misuse by untrustworthy entities, e.g. generation of presence logs. We argue that current IM systems do not take reasonable precautions to protect presence information. We propose an IM system designed to be robust against attacks to disclose a user's presence. It stores presence information in a distributed hash table (DHT) in a way that is only detectable and applicable for intended users and even not comprehensible for the DHT nodes. We apply an anonymous communication network to protect the users' physical addresses.